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Mixtures of nonfullerene acceptors (NFAs) are prepared to fine‐tune bulk heterojunction (BHJ) thin‐film morphologies. The acceptor phase resulting from these mixtures has unique physical properties with excellent optoelectronic processes that dictate the output of organic photovoltaic (OPV) devices. Remarkable short‐circuit current densities (JSC) and fill factors (FFs) are achieved due to the formation of better crystalline fibrils that suppress geminate recombination, leading to improved charge transport with enhanced crystallinity and aligned cascading energy levels confirm efficient exciton diffusion and dissociation, yielding more effective exciton recycling. The decreased Urbach energy and suppressed energetic disorder account for the improvement in the open‐circuit voltage (VOC). A maximum power conversion efficiency of 17.86% is obtained, underscoring the importance of using specific material interactions to produce a suitable morphology and manage energy loss, resulting in ideal organic solar cell (OSC) devices. [ABSTRACT FROM AUTHOR]

The issue of accumulated seashell waste has been increasingly addressed in the studies of its applicability as a secondary source of calcium carbonate. In this work, the mechanism of the thermo-oxidative degradation of two types of mollusk shells (Dosinia exoleta—DE and oyster Ostrea edulis—OE) was investigated using simultaneous thermal analysis. Physicochemical characterization of raw and calcined materials was performed by XRD and SEM techniques. Results show that increasing powder particle size and heating rate affect the degradation of investigated shells differently and have a significant contribution to released quantities of CO2. It was proposed that the calcination rate of DE powders is determined by the strain-induced collapse of CO2-deficient calcite at its interface with crystalline CaO rods-like structure, with simultaneous expulsion of CO2. A much higher CO2 concentration was identified during the degradation of OE powders, favoring the carbonation reaction and, consequently, increasing the temperature and activation energy of the investigated reaction. Under elevated CO2 concentration, the CaO aggregation step is enhanced by slower reaction kinetics at lower temperatures since both CO2 desorption and structural transformations are probably hindered. The proposed mechanism leads to a meaningful correlation between thermodynamic quantities (enthalpy–entropy compensation) in the form of an iso-kinetic relationship. [ABSTRACT FROM AUTHOR]

[Display omitted] • Crystalline Ni(OH) 2 /Amorphous NiMoS electrocatalyst were designed and synthesized by two-step hydrothermal process. • The as-obtained material shows excellent hydrogen evolution over all pH ranges. • The synergistic mechanism and the role of crystalline Ni(OH) 2 and amorphous NiMoS was elucidated. Designing and fabricating efficient electrocatalysts is a practical step toward the commercial application of the efficient hydrogen evolution reaction (HER) over all pH ranges. Herein, novel Ti@Ni(OH) 2 -NiMoS heterostructure with interface between crystalline Ni(OH) 2 and amorphous NiMoS was rationally designed and fabricated on Ti mesh (denoted as Ti@Ni(OH) 2 -NiMoS). Acid etching and calcination experiments helped in accurate elucidation of the synergistic mechanism as well as the vital role on crystalline Ni(OH) 2 and amorphous NiMoS. In acidic solutions, the HER performance of Ti@Ni(OH) 2 -NiMoS was mainly attributed to the amorphous NiMoS. In neutral, alkaline, and natural seawater solutions, the HER performance was mainly determined by the synergistic interface behaviors between the Ni(OH) 2 and NiMoS. The crystalline Ni(OH) 2 accelerated water dissociation kinetics, while the amorphous NiMoS provided abundant active sites and allowed for fast electron transfer rates. To deliver current densities of 10 mA·cm−2 in acidic, neutral, alkaline, and natural seawater solutions, the Ti@Ni(OH) 2 -NiMoS required overpotentials of 138, 198, 180 and 371 mV, respectively. This paper provides general guidelines for designing efficient electrocatalyst with crystalline/amorphous interfaces for efficient hydrogen evolution over all-pH ranges. [ABSTRACT FROM AUTHOR]

• The effect of cavities on recrystallization growth in SiC was investigated. • The formed cavities can retard the epitaxial growth. • Nanocrystalline SiC was observed in the cavity layer. The effect of cavities on recrystallization growth of amorphous SiC induced by a high fluence He implantation was investigated. 300 keV He ions were used to implant the 6H-SiC (0001) wafer to a fluence of 4.4 × 1017/cm2 at room temperature. A buried amorphous layer with a width of approximately 468 nm was formed. Moreover, many spherical bubbles with diameters over 25 nm were observed by transmission electron microscopy. Recrystallization of the buried amorphous layer was visible after 900 °C annealing for 30 min. Some irregular cavities were found in the damaged layer. The recrystallization started from the amorphous/crystalline interface, and the formed cavities retarded the epitaxial growth. Nanocrystalline SiC was formed in the cavity layer. Extended defects were also characterized by transmission electron microscopy. The research results will give an insight into the recrystallization process in amorphous SiC. [ABSTRACT FROM AUTHOR]

Pickering emulsions, stabilized by solid particles at the oil/water interface, are brought into focus due to their long‐term stability additional functionality and higher safety. Cyclodextrins are enzymatic derivatives of starch which have a hydrophobic inside cavity and a hydrophilic outside surface. Cyclodextrins aggregate and form crystalline nanoparticles at the interface of oil/water by self‐assembly which adsorbs on the surface of oil droplets to maintain the long‐term stability of the emulsion during the emulsifying process. Moreover, Cyclodextrins can form amphiphilic complex supermolecules nanoparticles with lipophilic molecules and be utilized to prepare functional Pickering emulsions owing to the appropriate size, reasonable structure, human edible, and environmentally benign. The review compiles and assesses the properties of cyclodextrins and the latest advances on preparations, characterizations, mechanisms and applications of Pickering emulsions stabilized by cyclodextrin nanoparticles. The results will help to deeply understand the structure and function relationship and expand the application of Pickering emulsion in various fields. [ABSTRACT FROM AUTHOR]

Molecular dynamics simulations are performed to investigate the effect of the interface structure, diffusion time and diffusion temperature on the diffusion behavior and amorphization mechanism of the dual-phase Mg alloys. The results indicate that there is a critical concentration of Y element in the amorphous/crystalline interface (ACI), which depends on the interface structure and temperature. And when the concentration of Y atoms in the ACI is higher than the critical concentration, the ACI will migrate towards the crystalline side, accompanied by the amorphization of the crystalline layer. In addition, it is found that the presence or absence of Y element in the amorphous layer has a significant impact on the amorphous layer thickness of the alloys. For the alloys containing Y atoms, the amorphous layer thickness increases with the increase of diffusion temperature and diffusion time. [ABSTRACT FROM AUTHOR]

A novel electrocatalyst containing amorphous FeSeO x and Mo doped NiSe 2 (denoted as FeSeO x /Mo-NiSe 2) was developed via pseudocrystalline replication method and selenization treatment, and heteroatom doping and amorphous and crystalline (a-c) interface enables attractive OER performances. [Display omitted] • A novel FeSeO x /Mo-NiSe 2 electrocatalyst was desinged for water oxidation. • The optimized FeSeO x /Mo-NiSe 2 exhibits a low overpotential of 205 mV at 10 mA cm−2 for OER in alkaline solution. • The excellent performance is attributed to amorphous and crystalline (a-c) interface engineering and heteroatom doping strategies. Exploring integrated regulation strategies to boosting electrocatalytic performance is essential to design more efficient and inexpensive OER catalysts. Herein, amorphous and crystalline (a-c) interface engineering and heteroatom doping are integrated to construct a novel electrocatalyst containing amorphous FeSeO x and crystalline Mo-doped NiSe 2 (denoted as FeSeO x /Mo-NiSe 2) via pseudocrystalline replication method and selenization treatment. The resultant FeSeO x /Mo-NiSe 2 electrocatalyst with 3D hierarchical nanoarchitectures of nanorod arrays covered by interlocking nanoblocks exposes more active sites and accelerated reaction kinetics. Furthermore, a-c interface engineering and heteroatom doping can synergistically enhance the intrinsic activity and charge transfer capability of NiSe 2 by decreasing the electron diffusion distance and flexibly modulating the electronic structure, which contributes to boost the oxygen evolution reaction (OER) performance. Consequently, the obtained FeSeO x /Mo-NiSe 2 achieves a low overpotential of 205 mV at 10 mA cm−2, which outperforms many other transitions metal selenides electrocatalysts. Density functional theory (DFT) calculations demonstrate that the formation of an internal electric field between FeSeO x and Mo-NiSe 2 accelerates charge transport and optimizes the adsorption/desorption of oxygen-containing intermediates, thereby accelerating the reaction kinetics and improving the OER performance. This work serves as a point of reference for designing innovative metal selenides based electrocatalysts combining a-c interface engineering and heteroatom doping. [ABSTRACT FROM AUTHOR]

Sodium ion batteries (SIBs) have garnered more and more attentions owing to the uneven distribution and increasing price of lithium mineral. Herein, BiVO 4 –V 2 C endogenous heterostructures as anode for SIBs are synthesized via one-step in situ hydrothermal method. The designed hydrangea-like heterostructure ensures a wide contact surface for the interaction of anode material with the electrolyte, and endows stable heterojunction interfaces between BiVO 4 and V 2 C MXene, the synergistic effect of which significantly improves the electrical conductivity, pseudo-capacitance and alleviates the volumetric change of BiVO 4 during charge/discharge process. Density functional theory (DFT) calculations ulteriorly demonstrate that the electric field at the BiVO 4 –V 2 C interface contributes to the excellent Na ion diffusion kinetics and impressive sodium storage capacity. As a result, the BiVO 4 –V 2 C anode achieved outstanding performance with a high discharge capacity (480 mAh g−1 after 600 cycles at 0.2 A g−1), and impressive long-term lifespan (303 mAh g−1 over 2000 cycles at 1 A g−1). This work reveals a new design of novel V 2 C MXene heterojunctions which coupling with BiVO 4 combined with the analysis of amorphous/crystalline interface, developing a proper strategy for the effective energy storage of sodium. An endogenous heterostructure of BiVO 4 coupled with V 2 C MXene (BiVO 4 –V 2 C) is developed via a one-step hydrothermal method. The designed hydrangea-like heterostructure provides a large surface area for the contact of the electrode material with electrolyte, and endows stable heterojunction interfaces between BiVO 4 and V 2 C, which significantly improves the reaction kinetics. [Display omitted] • Hydrangea-like endogenous BiVO 4 –V 2 C heterostructure is firstly reported. • Internal micro-electric field for improving Na+ migration and reaction kinetics. • The electrode delivers superior specific capacity and excellent cycle stability. • Endogenous heterostructure offers new insights for MXenes heterojunctions design. [ABSTRACT FROM AUTHOR]

Experiments have shown that high strength and high plastic stability are difficult to be simultaneously obtained in crystalline-amorphous layered composites. Here we report a complete suppression of plastic instability in a strong multilayered composite via nanoscale BCC Nb crystalline-amorphous CuNb interface architecting. Specifically, the size-dependent hardness and shear instability of the designed nanolayered composites are systematically investigated with individual layer thickness (h) ranging from 2 to 100 nm by nano/micro-indentation tests. A mechanics model is also proposed to quantify the shear instability. A non-monotonic shear instability behavior is revealed with decreasing h. When h > 40 nm, a cutting-like shear banding prevails in the composites and the shear instability reduces with decreasing h. Finally, a homogeneous plastic deformation without shear banding is achieved at h of 40 nm. For h < 40 nm, a kinking-like shear banding occurs in the composites and the shear instability increases with reducing h. Further theoretical analysis reveals a critical layer thickness for activating homogeneous deformation in the composites, i.e., 45 nm, above and below which the shear deformation would be dominated by cutting-like and kinking-like shear banding, respectively. The cutting-like shear banding is attributed to the propagation of the mature shear band formed in the amorphous phase that penetrates the crystalline layer. The homogeneous plastic deformation can be ascribed to the activation of the confined layer slip mechanism in the crystalline layer and the non-clustered shear transformation zones initiated in the amorphous layer. The kinking-like shear banding below 40 nm may originate from the cooperative kinking of the constituent layers with decreasing h. The potential advantage of the ductile BCC metals over FCC ones for suppression of shear instability in crystalline-amorphous composites is discussed based on the unique dislocation activities in nanoscale BCC crystals (e.g., self-multiplication and significant cross-slipping mechanisms). The present study sheds some light on designing strong and ductile crystalline-amorphous composites by selecting an appropriate BCC crystalline phase and an optimal interface spacing to eliminate plastic instability. • Shear instability of Nb/amorphous CuNb nanolayered composites is studied. • A mechanics model is proposed to quantify the shear instability. • A non-monotonic shear instability is discovered with decreasing layer thickness. • Shear instability is fully suppressed at 40 nm sample. • Cutting and kink-like shear bandings prevail respectively at large and small scales. [ABSTRACT FROM AUTHOR]

[Display omitted] • Anthracene-appended poly(ʟ-lactide)s (AAP) were synthesized by ROP of ʟ-lactide. • The excimer emission was observed in the low molecular weight AAP. • The monomeric emission is observed in amorphous and single crystals of AAP. • In crystallized AAP, fluorescence arises from anthracene excimers and monomers. • In the gel state AAP (e form), only the excimer emission was observed. The design and development of solid-state excimer-emitters bear great potential for attaining efficient solid-state luminescent materials. In this study, we have synthesized anthracene-appended poly(ʟ-lactide)s (AAPs) to regulate the arrangement of anthracene moieties by controlling the crystallization and polymorphic form of covalently linked poly(ʟ-lactide) (PLLA). In the high molecular weight AAP, the fluorescence intensity mainly arises from the monomeric anthracene moieties, whereas in the low molecular weight AAP, the excimer emission was observed depending on the structure and morphology of covalently-linked PLLA. The monomeric emission is predominantly observed in amorphous polymer due to the molecular level dispersion of covalently-linked anthracene moieties throughout the polymer matrix. When the polymer was crystallized under different conditions, covalently-linked anthracene moieties were excluded from polymer crystals or crystalline lamellae and are located on the surface or at the interface, which is advantageous for regulating the geometry of anthracene moieties. In the case of single crystals of PLLA, covalently-linked anthracene moieties assemble on the surface and emit mainly in their monomeric state due to the lack of π-stacking. In the melt-crystallized sample (α form), covalently-linked anthracene moieties reside at the interface of crystalline and amorphous domains by either dipolar interactions or π-stacking and fluorescence arising from anthracene excimers and monomers. In the gel state (ε form), only the excimer emission was observed due to the effective interactions between the anthracene moieties in the presence of excess solvent in the amorphous domains. In this way, polymer crystallization played a significant role in determining the arrangement of covalently-linked anthracene moieties in AAP. This study reveals the role of polymer crystallization on the excimer evolution in fluorophore-appended semicrystalline polymers and provides new insight into the design and development of fluorophore-appended polymers for optoelectronic devices. [ABSTRACT FROM AUTHOR]

• A method for developing models of realistic CASS microstructure is shown. • Simulated sound fields in CASS models agree well with experimental sound fields. • Simplified CASS models using Voronoi regions outperformed the realistic CASS models. • Large variations in echo amplitude were observed when randomizing the CASS model microstructure. Ultrasonic inspection of cast austenitic stainless steel (CASS) in the nuclear industry is particularly challenging because of sound field scatter and attenuation caused by the coarse-grained microstructure. Modeling and simulation are important tools in ultrasonic testing, as they can be used to help address key aspects of inspections, such as developing new probe designs, predicting inspection reliability, and testing phased-array focal laws. However, developing a useful and reliable CASS model is challenging due to the many grain interfaces and crystalline orientations that must be captured. We demonstrate a method of creating a realistic CASS model that is usable in CIVA, a commercially available modeling and simulation software platform. Using polished and chemically etched sections to highlight the grain structure and orientation, we generate models of a coarse-grained equiaxed specimen and a columnar specimen. We also test an alternative method of generating a coarse-grained model using Voronoi regions. We qualitatively compare sound field scatter and quantitatively compare sound field attenuation and beam partitioning in simulated sound fields to those of laboratory-measured sound fields. Results show that the Voronoi models perform as well as or better than the models based on actual grain morphology. We also show that model-to-model randomness in Voronoi grain structure can impact the magnitude of a simulated echo response by a factor of two or more. Although CASS models are potentially a good depiction of reality for a given scenario, they should not be considered representative since CASS morphology can change significantly from specimen to specimen or within the same specimen. [ABSTRACT FROM AUTHOR]

[Display omitted] • The crystallization process of amorphous YAG oxide is investigated from an atomic point of view. • The crystallization proceeds on the surface and interior of the amorphous YAG separately, and which show the preferential crystallization of the surface atoms. • Some atoms in the amorphous phase were controlled by the periodic potential field of the crystal atoms and produced dynamically changing semi-ordered structures at the amorphous/crystalline interface with mainly concentrated within 1–2 nm from the interface. The transformation from amorphous materials to crystals and the corresponding microscopic mechanism have become a research focus in materials science, condensed matter physics, and biophysics etc. In this paper, taking Y 3 Al 5 O 12 (YAG) as an example, the crystallization process of amorphous YAG oxide is investigated from an atomic point of view through the combination of spherical aberration-corrected transmission electron microscopy (SCTEM) with an in situ heating method, and the morphology and structural evolution of the surface and interface are explored. It is observed that the crystallization proceeds on the surface and interior of the amorphous YAG separately. Through atomic-scale imaging, it is determined that semi-ordered structures are formed in a few atomic layers at the amorphous/crystalline interface and that the structural transformation process from the amorphous to the semi-ordered state and then to the crystal structure may be the main reason for the multiple stages of the crystallization of amorphous oxides. This study demonstrates the mechanism of the amorphous-to-crystal transformation on the atomic scale and contributes to gaining a better understanding of the crystallization process of bulk oxides, especially complex metal oxides. [ABSTRACT FROM AUTHOR]

Bismuth telluride-based thermoelectric (TE) devices were widely used in waste heat recovery due to their high thermoelectric figure of merit (ZT), but the severe diffusion between Sn-based solder and TE pillar generated porous and brittle Sn-Te intermetallic compound (IMC), which seriously restricted the reliable service of devices. Ni-based coating was used but the thick Ni-Te IMC also impaired the properties of TE pillars. In this work, the crystalline Co-P coating was inserted between the p-type TE material Bi 0.5 Sb 1.5 Te 3 and the solder by electrodeposition, and the power generation sustainability of the TE pillar were significantly improved, and the mechanism was revealed. The microstructural characterization proved that the Co-P coating could effectively resist the diffusion of active Sn, Bi, Sb, Cu atoms. Co-P coating would provide support for the structural integrity and performance sustainability of TE pillars. It was worth noting that an ultrathin CoTe 2 IMC layer was formed between the Co-P coating and the Bi-Sb-Te pillar, which was much thinner than the Ni-Te IMC layer reported in the literature. This indicated that Co-P only consumed little thermoelectric elements, but also a good metallurgical bond was formed between the Co-P and the Bi-Sb-Te. After aging at 423 K for 150 h, the maximum output power and average Seebeck coefficient of the TE pillar without coating dropped significantly by 74% and 34%, respectively, and the internal resistance rose by 67%. Remarkably, the maximum output power and average Seebeck coefficient of the TE pillar protected by the Co-P coating only decreased by 14% and 5%, respectively, and the internal resistance only increased by 6%. [Display omitted] • Co-P coating showed a remarkable effect on the sustainability of TE power generation. • Co-P coating could effectively resist the diffusion of active Sn, Bi, Sb, Cu atoms. • An ultrathin CoTe 2 IMC layer was formed between the Co-P coating and the TE pillar. • Co-P coating consumed less thermoelectric elements than Ni-based coating. [ABSTRACT FROM AUTHOR]

Making composites with crystalline inclusions can improve plasticity in brittle metallic glasses. In this study, we show a new metallic glass matrix composite designed with a gradient network architecture made of amorphous matrix regions and gradient crystalline network regions. Using molecular dynamics simulations, we validated theoretically the hypothesized concept of this new composite. Our results show that the unique microstructure leads to significant strain delocalization which can delay the generation of catastrophic shear bands. This is resulted from the new mechanism by both forming diffuse embryonic shear bands in the thin crystalline network interface and hindering or guiding their formation and movement in thick crystalline network regions with the presence of internal stresses generated from the gradient. This work demonstrates the synergistic effects induced by the heterogeneous gradient network design in the mechanical properties of metallic glass matrix composites and may open up exciting new possibilities. Macroscopic plasticity can be improved by spatially patterning heterogeneity into "microstructures" in the homogeneous structure-less amorphous metals. By further introducing gradients in the microstructure, we can elevate the improvement to a new level. Here, we show a new metallic glass matrix composite designed with a gradient network architecture made of amorphous matrix regions and gradient crystalline boundary network regions (a). The designed gradient structure can greatly enhance the plasticity as compared to the monolithic metallic glass (MG) and nanoglass (NG) (b). The new design of the MG composite creates a hierarchical heterostructure in the spatial pattern that can effectively cause delocalization of local shear (c) and the significant delay of brittle fracture. [Display omitted] [ABSTRACT FROM AUTHOR]

Nano-porosity in amorphous Ge formed by swift heavy ion irradiation displays a peculiar self-organisation process. Initially almost randomly distributed pores grow with increasing irradiation fluence and segregate in layers orientated parallel to the sample surface. This self-organisation mechanism depends on the ion energy, thickness of the amorphous Ge layer and the angle of ion incidence and shows a characteristic length depending on ion energy and irradiation angle. Molecular dynamics simulations of individual ion tracks show that voids form due to the transition from the low-density amorphous to the high-density liquid phase, which also gives rise to a flow directed away from large pores and surfaces. The flow results in a characteristic distance from surfaces and larger pores, below which new voids do not form, and supports the formation of voids at the amorphous/crystalline interface. Simulations also demonstrate that, while direct impacts can reposition small voids, partial or nearby impacts promote their growth at the same location. These processes are plausible drivers for the self-organization. [Display omitted] [ABSTRACT FROM AUTHOR]

Order/dis-order atomic arrangements in crystalline/amorphous structure possess a complementing effect in electro-catalysis as the former one can offer a long-range electronic conducting path, whereas the latter is rich with active sites. However, atomic level interfacing of crystalline and amorphous structures is extremely challenging and thus often end-up with uncontrolled secondary deposition one above another. Here, we are reporting second-scale atomic rearrangement of crystalline oxide nanowire surface into amorphous molybdenum sulfide shell that displayed excellent hydrogen evolution activity. Employing transient heating by microwave-activated graphene filament, surface atoms of molybdenum tungsten oxide (MoWO) nanowire can be arrested in either an amorphous or crystalline state during their sulfidation. Such a nanowire structure consisting of crystalline oxide core-amorphous sulfide shell shows excellent catalytic activity for hydrogen evolution reaction (HER) and exhibits an overpotential of 136 mV at 10 mA cm−2 in the acid electrolyte, which is much lower than the overpotential of parent oxide nanowire (356 mV) and its fully sulfurized crystalline counterpart (163 mV). As-developed catalyst also shows competitive HER performance with excellent alkaline and neutral electrolytes stability, thereby qualifying it as a pH universal catalyst. A detailed density functional theory calculation reveals oxide core promoted activation of multiple sites of amorphous sulfide phase, which provide key insights of electronic modulation via crystalline/amorphous interfacial structure for HER catalysis. This rapid and highly facile technique can lay the platform for the development of generic crystalline/amorphous core-shell nanostructure and their possible use as cost-effective and efficient catalysts. [Display omitted] • The unique microwave-induced second-scale surface amorphization is demonstrated. • Amorphous@crystalline core-shell nanowire of a-MoS x @MoWO structure was realized. • The a-MoS x @MoWO exhibits excellent pH-universal HER activity. • Synergy between core and shell for HER is studied by detailed DFT calculation. • Crystalline core turns multiple inactive sites of amorphous shell to highly active. [ABSTRACT FROM AUTHOR]

[Display omitted] • High-entropy alloy nanolaminates are obtained. • The coherent interface in nanolaminates is designed to improve ductility. • The crystalline/amorphous hierarchical nanostructure is designed to enhance strength. Introducing nanolaminates structure is a promising strategy to obtain the controllable microstructure and mechanical properties of high entropy alloy (HEA). In this work, the Al 0.5 CoCrFeNi/CoCrCuFeNi nanolaminates with coherent interface and crystalline/amorphous hierarchical nanostructure was designed. On the one hand, the coherent interface with continuous slip direction and planes enables nanolaminates with great deformability. On the other hand, the hierarchical nanostructure in the nanolaminates contributes to high strength via the interaction between crystalline and amorphous structures. Microstructural observations indicated that abundant nanotwins and stack faults were filled in the columnar nanocrystalline cutting across the interface, leading to a high hardness due to the dislocation-interface interactions. The results of nanoindentation tests revealed that the hardness of the nanolaminates up to 8.02 GPa, which markedly exceeds many HEA films with face-centered cubic (FCC) phase. The findings provide a new avenue for improving the mechanical properties of HEA nanolaminates in a controllable manner. [ABSTRACT FROM AUTHOR]

Transition metal borides have shown great promise as a supercapacitor electrode material. However, the amorphous structure of metal borides leads to the structural collapse of electrode material during electrochemical cycling, which seriously affects the stability of the material. In the present work, we successfully construct amorphous/crystalline NiCoB@NiCo 2 S 4 heterogeneous interfacial composites by introducing the outer layer of sulfide to improve the electrochemical performance. NiCoB@NiCo 2 S 4 shows a specific capacitance of 1562 F g−1 at a current density of 1 A g−1 and still possesses 58% specific capacitance even at a higher current density of 50 A g−1. The asymmetric supercapacitor (ASC) device assembled with Bi 2 O 3 @C as the negative electrode and NiCoB@NiCo 2 S 4 as the positive exhibits a high energy density of 98.75 Wh kg−1 at a power density of 750 W kg−1. The ASC also exhibits excellent cycling stability with capacitance retention of 118% after 10000 cycles at a current density of 10 A g−1, which fully demonstrates the practical applications value of NiCoB@NiCo 2 S 4 //Bi 2 O 3 @C. The amorphous/crystalline NiCoB@NiCo 2 S 4 heterogeneous interfacial composites were successfully constructed for the first time. The resulting amorphous/crystalline heterogeneous interface effectively improves the electron/ion transport rate and increases the electrochemical reactive sites. The assembled NiCoB@NiCo 2 S 4 //Bi 2 O 3 @C asymmetric supercapacitors exhibit a high energy density of 98.75 Wh kg−1 due to the high specific capacitance potential of NiCoB@NiCo 2 S 4 and Bi 2 O 3 @C. The introduced crystalline outer cladding metal sulfide effectively inhibits the oxidation of the metal boride core, thus exhibiting excellent electrochemical cycling stability. [Display omitted] • Amorphous/crystalline NiCoB@NiCo 2 S 4 interface structure was firstly constructed. • NiCoB@NiCo 2 S 4 showed 1562 F g−1 at 1 A g−1. • The ASC had a high energy density of 98.75 Wh kg−1. [ABSTRACT FROM AUTHOR]

Microstructures and mechanical properties of Ni matrix composites reinforced with amorphous SiO 2 particles by in-situ pyrolysis of polycarbosilane (PCS) coated on Ni powders were studied in this paper. The submicron spherical amorphous SiO 2 particles instead of traditional SiC uniformly distributing in the composites result from the generated silicon source by PCS pyrolysis combined with oxygen impurity in the preparation. The prepared composites achieve high yield strength, 172 MPa, and ultimate tensile strength, 494 MPa, as well as outstanding ductility, total elongation 28.4 %, which is improved 13.9 %, 50.6 % and 160.6 % compared with those for pure Ni samples, respectively. The effects of solid solution strengthening, grain refinement strengthening, reinforcement particle strengthening and dislocations behavior of at amorphous/crystalline interface on the combination of high strength and ductility of the composites were discussed. [Display omitted] • Amorphous SiO 2 reinforced Ni matrix composites were fabricated by in-situ pyrolysis of polycarbosilane coated on Ni powders. • Amorphous SiO 2 instead of crystalline SiC formed by the combination of silicon generated in the pyrolysis with oxygen. • The composites exhibit a combination of excellent tensile strength and ductility. [ABSTRACT FROM AUTHOR]

Developing earth-abundant, efficient and durable catalysts toward the hydrogen evolution reaction (HER) is critical for the large-scale deployment of sustainable hydrogen production from renewable energies. Transition metal dichalcogenides (TMDs) are promising candidates for the replacement of precious and state-of-the-art platinum-groups-metals, but their HER performance still needs improvement. Constructing crystalline/amorphous interfaces is effective in terms of creating abundant active sites for boosted catalytic activity. Therefore, in this study, defective crystalline vanadium disulfide/amorphous molybdenum sulfide/reduced graphene oxide (c-VS 2 /a-MoS x /RGO) nanocomposites are fabricated via a combined hydrothermal-plasma method. The HER performance of c-VS 2 /a-MoS x /RGO is optimized by tuning the plasma treatment duration and the amount of precursors, and the corresponding mechanisms were investigated by morphological and elemental analyses. Taking advantage of the high reactivity of low-temperature plasma, the strategy presented in this work is effective in terms of constructing crystalline/amorphous interfaces and introducing multiple defects, which creates abundant active sites and ultimately results in boosted HER performance. The optimal c-20VS 2 /a-40MoS x /RGO catalyst exhibited excellent HER activity (η@100 mA cm−2 = 193 mV and η@500 mA cm−2 = 244 mV) and good stability. This work provides a facile and effective strategy for promoting the HER performance of TMDs and sheds light on rationally designing efficient HER catalysts using earth-abundant elements. [Display omitted] This work describes a combined hydrothermal-plasma method for fabricating defective crystalline vanadium disulfide/amorphous molybdenum sulfide/reduced graphene oxide (c-VS 2 /a-MoS x /RGO) nanocomposites toward hydrogen evolution reaction. The HER activity of c-VS 2 /a-MoS x /RGO can be optimized by adjusting plasma treatment duration and the amount of precursors. Structural and electrochemical characterizations indicate that the optimal c-VS 2 /a-MoS x /RGO catalyst possess abundant active sites, which can be attributed to crystalline/amorphous interface and multiple defects in the heterostructures. The c-VS 2 /a-MoS x /RGO catalysts show excellent activity and good stability for the HER. • This work develops a method for constructing crystalline/amorphous interfaces. • Crystalline/amorphous interfaces are beneficial for boosting HER activity. • The level of lattice defects should be controlled for optimal HER activity. • c-VS 2 /a-MoS x /RGO exhibits boosted HER performance at high current densities. [ABSTRACT FROM AUTHOR]

Although the synthesis of amorphous/crystalline heterojunction is still difficult due to thermodynamic instability, the introduction of amorphous components not only avoids lattice mismatch but also triggers higher photoelectric activity at the interface, making it particularly attractive. Herein, a novel amorphous ZnO/crystalline N-TiO 2 heterojunction (aZn/NT) was firstly synthesized by a simple one-pot synthesis process. Non-specific preparation conditions and inexpensive raw materials [e.g., zinc acetate, bis(ammonium lactate) titanium hydroxide (TALH) and citric acid] are significant indicators of this method. The systematic test shows that the hydrolysis of TALH is independent and precedes the substitution reaction of citric acid to form a composite spherical structure. Different testing methods have shown that the newly formed bonds (Ti-O-N-Zn or Ti-N-O-Zn) between the two components during the hydrothermal process are the basis of the heterostructure association. Moreover, the combination of positively charged surfaces, abundant oxygen vacancy defects, and transport channels accelerates the photoreduction of Cr(VI) on aZn/NT surface. The high catalytic rate [0.022 min−1 for 200 mg L−1 Cr(VI)] and low activity loss rate (∼2.3% within 5 cycles) under optimal conditions indicate that the synthesis of highly active heterogeneous materials can be achieved through a simple path. [Display omitted] • A new type of amorphous/crystalline heterojunction interface has been simply constructed. • The interface structure changes the photoelectric properties and interfacial adsorption behavior of composite materials. • The metal oxygen bridge bonding effect, oxygen vacanciesand surface positive charges support the rapid reduction of Cr(VI). [ABSTRACT FROM AUTHOR]

The comprehensive understanding of the Ohmic contact mechanism on the front metalization is highly desirable for further improvement of crystalline silicon solar cells performance. However, there are still controversial views about current transport paths between silver electrode and silicon emitter. To clarify this significant issue, we applied the selective acid etching (AE) process and the method of mechanical stripping process to prepare proper samples for direct observation of the Ag/Si contact interface. It is revealed that four kinds of Ag crystallites are grown with variant shapes and sizes on the pyramid tips, {111} planes, edges and tiny bumps at valleys of the textured Si surface resulting from anisotropic etching of Si emitter by the flowing molten glass frit during firing and the consequent epitaxially growth of Ag on the etching pits during cooling. All these Ag crystallites are in direct contact with Si emitter, serving as the most important contact points on the Si side. Meanwhile, three kinds of spherical Ag particles are formed in the resolidified glass frit during cooling which are crucial tunneling paths, conducting between glass-covered Ag crystallites on silicon and Ag bulk above. As a whole, four current transport paths are suggested mainly via Ag crystallites, Ag particles or both. In addition, the four electron transport paths are further confirmed by the Kelvin probe force microscopy characterization. The clarification and detailed understanding of all current transport paths are key points to design better silver paste and sintering process, and hence to improve the solar cell performance. • Four kinds of Ag crystallites with variant shapes and sizes on different areas of pyramids due to anisotropic etching. • Three kinds of spherical Ag particles in the resolidified glass frit. • Four current transport paths at sintered Ag/Si interface of crystalline silicon solar cells. • Models and KPFM characterization of four current transport paths. [ABSTRACT FROM AUTHOR]

[Display omitted] • a/c-RuCoMo y O x /NF was synthesized by coprecipitation-microwave method. • Microwave time affects the transition from crystalline to amorphous structure. • a/c-interface and electron interaction make a/c-RuCoMo y O x /NF have mighty activity. • The η 10 value of a/c-RuCoMo y O x /NF is 39 and 166 mV for HER and OER. Due to the vast difference in structure and the unique electronic state at the heterointerface, the amorphous/crystalline (a/c) heterostructure exhibits excellent potential in electrocatalysis. However, there are great challenges in constructing the material with ample a/c-heterointerfaces and controllably modulated a/c-heterointerface region through a simple one-step method. Herein, the a/c-RuCoMo y O x /NF (nickel foam) electrocatalyst is synthesized by the coprecipitation-microwave treatment method. Notably, microwave time directly affects the ratio of amorphous region (RuCoMoO x) to crystalline region (CoMoO 4 and CoO). Surprisingly, the a/c-RuCoMo y O x /NF with abundant crystallinity/amorphous heterointerfaces exhibits the ultralow η 10 values of 39 and 166 mV for HER and OER, which are 0.5-fold and 0.63-fold lower than that of Pt/C-NF and RuO 2 -NF benchmarks, respectively. Overall, this work provides a novel idea and convenient method for the construction of amorphous/crystalline heterointerfaces with modulated interface region, and guides the direction for the preparation of superior electrocatalysts by regulating the a/c-heterointerface region. [ABSTRACT FROM AUTHOR]

[Display omitted] • NiCr-based composites with crystalline Cr 3 C 2 and amorphous SiO 2 dual-particles were successfully fabricated. • The composites exhibit a combination of excellent tensile strength and ductility. • The generation and annihilation behavior of dislocations at amorphous/crystalline interface contributes to improve tensile strength and ductility. • Introducing crystalline-amorphous dual-particles into metallic materials can simultaneously improve their strength and ductility. Strength and ductility of structural materials are mutually exclusive in general due to the strength-ductility trade-off. Using in-situ pyrolysis of polycarbosilane in NiCr powder green compacts, we fabricated NiCr-based composites with micro-sized crystalline Cr 3 C 2 and amorphous SiO 2 dual-particles. Tensile tests show that the NiCr-based composites have a combination of high strength and ductility with the yield strength, ultimate tensile strength and ductility as 449 MPa, 838 MPa and 20.5%, respectively. The amorphous SiO 2 and crystalline Cr 3 C 2 particles exhibit plastic deformation and transgranular fracture, respectively, under tensile stress. Besides solid solution strengthening, the generation and annihilation behavior of dislocations at amorphous/crystalline interface and the strain hardening of the ceramic particles by hindering the movement of dislocations mutually contributes to the combination of excellent strength and ductility of our composites. [ABSTRACT FROM AUTHOR]

An intrinsic feature of nearly all internal interfaces in crystalline systems (homo- and hetero-phase) is the presence of disconnections, namely topological line defects constrained to the interface that have both step and dislocation character. We demonstrate that elastic interactions between disconnections strongly affect the morphology and motion of interfaces, allowing for understanding and reconciling diverse key experiments. In particular, these elastic interactions strongly modify equilibrium interface morphologies compared with those solely determined by anisotropic surface energy, and affect the kinetics of migrating interfaces. They are also found to lead to a thermodynamic, first-order, finite-temperature, faceting–defaceting transition. We demonstrate these phenomena through numerical simulations based upon a general, continuum disconnection-based model for interface thermodynamics and kinetics applied to embedded particles/grains, steady-state interface migration geometries, and nominally flat interfaces. [Display omitted] [ABSTRACT FROM AUTHOR]

ZSR-P loaded nano-TiO 2 composite photocatalysts (TiO 2 /ZSR-P) have been prepared by the sol–gel method using the by-product Zr-containing silica residue (ZSR) as precursors during the production process of zirconium oxychloride, the structure and properties of TiO 2 /ZSR-P were characterized in this paper. The results showed that the TiO 2 /ZSR-P composite photocatalysts were characterized by the uniform loading of nano-TiO 2 on the surface of amorphous SiO 2 particles in ZSR-P. TiO 2 and SiO 2 were combined by forming -Ti-O-Si- bonds at the interface and the crystalline structure of TiO 2 powders was identified a mixed phase of anatase and rutile, its loading amount was 17.14%, the particle size raged from 7 to 12 nm. The degradation rate of TiO 2 /ZSR-P to the concentration of 5 ppm and 10 ppm methyl orange solution reached 99.52% and 100% respectively after 140 min of ultraviolet irradiation, and it still maintained stable performance after repetitive-use of the catalyst for 4 times. [ABSTRACT FROM AUTHOR]

Diamond-structured grain boundaries (GBs) are important because they have notable effects on the performances of many functional devices. Previous studies have suggested that the most stable structures of some silicon GBs can be obtained by structural reconstruction from some meta-stable GBs explored at 0 K by atomic simulation. While GB reconstruction is possible to enable these meta-stable GBs to exist at elevated temperatures, reports on such behaviors are rare. This work unveiled a non-reported GB reconstruction from two degenerate ground-states of a well-known silicon GB which can be distinguished by an orientational feature of their unit structures. The reconstructing structures were verified stable by density-functional-theory (DFT) simulation. By thermodynamical and kinetical discussion, we have shown that the structural variation of this well-known GB at elevated temperatures is more likely to be dominated by this reconstruction mechanism rather than by transforming to other metastates. Such a reconstruction mechanism allows the whole GB system to be treated as an Ising model with a second-ordered phase transition. By applying harmonic transition state theory, we predicted the possible concentration of the defects induced by reconstruction at elevated temperatures and discussed their effects on the band structure of the GB by DFT simulation. An explanation was made on the cause of the difference between the phase transition behavior of this silicon GB and that of a reported copper GB. Our research made new insights into understanding the behavior of reconstructing interfaces in covalent-bonded crystalline materials. [Display omitted] [ABSTRACT FROM AUTHOR]

Azobenzene liquid crystalline (ALC) ligand contains a cholesteryl group linked to an azobenzene moiety through a carbonyl dioxy spacer (C7) and terminated with an amine group as a polar head. The phase behaviour of the C7 ALC ligand at the air-water (A-W) interface is investigated employing surface manometry. The surface pressure-area per molecule isotherm shows that C7 ALC ligand exhibit two different phases following the phase sequence viz., liquid expanded (LE 1 and LE 2) and then collapse to three-dimensional crystallites. Further, our investigations under different pH conditions and in the presence of DNA reveal the following. Compared to the bulk, the acid dissociation constant (pK a) of an individual amine reduces to 5 at the interfaces. For pH (3.5) < pK a , the protonation of amine groups of C7 ALC ligand facilitates the condensation of the film and enhances the stability. For pH values > pK a , the phase behaviour of the ligand remains the same due to the partial dissociation of the amine groups. The presence of DNA in the sub-phase result in the expansion of isotherm to the higher area per molecule and the compressional modulus extracted reveals the phase sequence; liquid expanded, liquid condensed, followed by a collapse. Further, the kinetics of adsorption of DNA to the amine groups of the ligand is investigated, suggesting the interactions are influenced by surface pressure corresponding to different phases and pH of the sub-phase. Brewster angle microscope studies are carried out at different surface densities of the ligand as well as in the presence of DNA also supports this inference. Atomic force microscope is employed to acquire the surface topography and height profile of C7 ALC ligand (1 layer) after transferring on onto a silicon substrate using Langmuir Blodgett deposition. The difference in the surface topography and thickness of the film indicates the adsorption of DNA onto the amine groups of the ligand. The characteristic UV–visible absorption bands of the ligand films (10 layers) at the air-solid interface are tracked and the hypsochromic shift of these bands is also attributed to these DNA interactions. [Display omitted] • Phase behaviour of C7 azobenzene liquid crystalline (ALC) ligand at the air-water interface is investigated. • Surface manometry studies reveal the condensation of the ligand due to the protonation of amine groups for pH

Analyzing the orientation of polymeric crystalline lamella at the surface of thin films can be challenging. Even though atomic force microscopy (AFM) is often sufficient for this analysis, there are cases when imaging is not sufficient to confidently determine lamellar orientation. Here, we used sum frequency generation (SFG) spectroscopy to analyze the lamellar orientation at the surface of semi-crystalline isotactic polystyrene (iPS) thin films. The SFG orientation analysis indicated that the iPS chains are oriented perpendicular to the substrate (flat-on lamellar orientation), which was confirmed by AFM. By analyzing the evolution of the SFG spectral features with the progress of crystallization, we demonstrated that the ratios of the SFG intensities of the phenyl ring resonances are a good indication of the surface crystallinity. Furthermore, we explored the challenges associated with SFG measurements of heterogeneous surfaces, which is commonly present in many semi-crystalline polymeric films. To the best of our knowledge, this is the first time that the surface lamellar orientation of semi-crystalline polymeric thin films was determined by SFG. Also, this work pioneers in reporting the surface conformation of semi-crystalline and amorphous iPS thin films by SFG and in linking the SFG intensity ratios to the progress of the crystallization and the surface crystallinity. This study demonstrates the potential applicability of SFG spectroscopy in the conformational analysis of polymeric crystalline structures at interfaces and opens the way to the investigation of more complex polymeric structures and crystalline arrangements, especially for the case of buried interfaces, where AFM imaging is not an option. [Display omitted] • Surface lamellar orientation of polymer thin films determined by SFG. • Surface of semi-crystalline iPS thin films is dominated by flat-on crystals. • SFG intensity ratios are directly linked to the surface crystallinity. • Higher level of backbone ordering in semi-crystalline films than in amorphous films. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZB-MnTe thin films are epitaxially grown by MBE in spite of the metastable nature. • High-crystalline quality, atomic surface flatness and sharp interface are yielded. • PL emissions of 4 T 1g (4 G) and 4 T 1 (4 G) related to Mn2+ d - d multiplets are observed. • Two extra PL transitions attributed to STE states are demonstrated below T N. • Dynamics of photoexcited d -electrons are strongly correlated to the AFM transition. Single-crystalline γ -MnTe thin films with zinc-blende structure were grown epitaxially on InP(1 1 1) by molecular beam epitaxy. Two-dimensional growth regime and atomic surface flatness are achieved, and appearance of Laue's oscillation peaks illustrates the superior crystalline quality and interface of γ -MnTe films. A pseudocrystal buffer layer is formed at interface releasing the strain led by the large lattice mismatch between γ -MnTe and InP, and then growth of γ -MnTe films with a perfect lattice evidences the high-quality crystallinity in a fully relaxed state. Photoluminescence (PL) emissions from 4 T 1g (4 G) and 4 T 1 (4 G) related to Mn2+ ions d - d multiplets are observed with their respective activation energies of ∼142.5 meV and ∼323.5 meV. Such high potentials reflecting the nonradiative recombination indicate the thermal stability of these PL. Moreover, two extra PL transitions assigned to be the emissions from self-trapped exciton (STE) states are found below T N. Time-resolved PL (TRPL) spectra at various temperatures indicate that the relaxation dynamics of photoexcited d -electrons is strongly correlated to the antiferromagnetic ordering transition due to the synergy of magnon, phonon and STE states. These findings suggest that introduction of STE states in a material by controlling its magnetic ordering qualifies the competition in optoelectronics devices. [ABSTRACT FROM AUTHOR]

• • The large-sized 4H-SiC single crystals were grown via sublimation technique. • • Impact of crucible structure on growth behavior was systematically investigated. • • SiC crystal grown in specific crucible exhibits superior characteristics. Silicon carbide (SiC), as the wide bandgap semiconductor, has gradually attracted attention from investigators due to the excellent integrated performance, widely recognized as a revolution in the electronic devices. For these applications, it is crucial to prepare the high-quality SiC crystal ingot by optimizing growth parameters and crucible structures. In this study, the effect of TaC coating and graphite paper on the growth process of SiC ingot were investigated compared to the growth in conventional graphite crucible through modeling and experiment. We demonstrated that the grown crystal using TaC-coated graphite relay ring and graphite paper surrounded the inner wall of powder container shows the superior characteristics in terms of the crystalline perfection and interface shape. In addition, the new crucible structure can provide a low-cost solution to prepare SiC crystal ingot using PVT method. [ABSTRACT FROM AUTHOR]

We constructed a unique heterointerface of crystalline Au nanoparticles and amorphous porous CoSnO 3 nanocubes for sensitive electrochemical detection of glucose. [Display omitted] • Au/CoSnO 3 was explored as a novel electrocatalyst for highly sensitive nonenzymatic detection of glucose. • It is the first time that CoSnO 3 is employed as electrocatalyst for glucose oxidation. • The formation of a unique amorphous/crystalline heterogeneous interface makes Au/CoSnO 3 exhibit remarkable catalytic performance for glucose detection. Au/CoSnO 3 was explored as a novel electrocatalyst for highly sensitive nonenzymatic detection of glucose. Au/CoSnO 3 was synthesized by a galvanic replacement strategy. The obtained nanomaterials were characterized by transmission electron microscopy (TEM), energy-dispersive X-ray spectrometry (EDS), X-ray diffractometry (XRD) and electrochemical techniques. The results display that a small amount of crystalline Au nanoparticles are decorated on the surface of amorphous porous CoSnO 3 nanocubes. The formation of such unique amorphous/crystalline heterogeneous interface makes Au/CoSnO 3 exhibit excellent electrocatalytic activity for the electrochemical oxidation of glucose. The sensor based on Au/CoSnO 3 can detect glucose with a wide linear detection range of 0.2 µM–0.11 mM, a high sensitivity of 2317.1 µA·mM−1·cm−2 and a low detection limit of 0.078 µM. This study demonstrates CoSnO 3 as an effective sensing material and also provides a way to improve electrocatalytic properties of nanomaterials through interfacial engineering. [ABSTRACT FROM AUTHOR]

• Innovative passivating contact using quantum well at poly-Si/c-Si interface. • Efficacy of quantum well on large-area TOPCon device is discussed. • The quantum well improves the V oc by 20 mV. • The quantum-well device achieves an efficiency of 23.91%. Polysilicon/crystalline silicon (poly-Si/c-Si) passivating contact is attracting attention as a promising passivation technology for c-Si solar cells. Recently, we have proposed a quantum-well passivating contact (QWPC) that uses a quantum-well at the poly-Si/c-Si interface to suppress recombination, such as Auger and/or Shockley-Read-Hall recombination, due to deep dopant-diffusion problems from poly-Si into the c-Si absorber and, as a result, promote the passivation quality. Herein, we demonstrate the effectiveness of the QWPC in a large area (272.13 cm2) of c-Si photovoltaic devices. A reference device, featuring a front boron diffusion emitter and normal rear poly-Si/c-Si passivating contact without QWPC, achieves a certified 22.99% conversion efficiency. The QWPC significantly reduces recombination losses within the device, as demonstrated by bias external quantum efficiency and dark I-V characteristics. The QWPC improves the open-circuit voltage (V oc) by 20 mV. An antireflection magnesium fluoride coating applied at the front along with the QWPC improves the short-circuit current density by 1.27 mA/cm2. The QWPC device achieves a conversion efficiency of 23.91%. The QWPC demonstrates an innovative passivating contact for promoting c-Si solar cell performance. [ABSTRACT FROM AUTHOR]

GdPO 4 is a promising thermal barrier coating (TBC) candidate owing to its excellent resistance to calcium-magnesium-alumina-silicate (CMAS) and molten salt corrosion. In this study, the corrosion behavior of GdPO 4 in CMAS + molten salt (CN) was investigated and compared with that in CMAS. At 1200 and 1250 °C, interface reaction layers rapidly formed on both the CN and CMAS attacked GdPO 4 pellets, and many crystalline products were generated in the melts. This effectively increased the melt viscosity and suppressed its penetration. As compared to CMAS, CN was more aggressive to GdPO 4 at 1200 °C but less at 1250 °C. [Display omitted] • CMAS + NaVO 3 (CN) and CMAS corrosion behavior of GdPO 4 was studied and compared. • The interface reaction layers on the CN and CMAS attacked GdPO 4 pellets had different phase compositions. • The reactive crystalline products in CN and CMAS melts on GdPO 4 pellets were different. • The formed crystalline products and interface reaction layers increased the melt viscosity and inhibited melt penetration. • As compared to CMAS, CN was more aggressive to GdPO 4 at 1200 ℃ but less at 1250 ℃. [ABSTRACT FROM AUTHOR]

[Display omitted] The CSL/DSCL model for interfaces in crystalline materials offers a unified framework to study interface dislocations in phase boundaries and disconnections in grain boundaries. The model relies on the existence of a coincidence relation between the two lattices that meet at an interface. The model's ability to quantitatively predict the thermodynamics and kinetics of interfaces has been demonstrated for a limited set of symmetric tilt grain boundaries (STGBs) in cubic materials and twin boundaries. However, the lack of a general framework of interface defects prevents its applicability to arbitrary rational boundaries. In this paper, we present a mathematical framework based on the Smith normal form (SNF) for integer matrices to study the bicrystallography of rational phase and grain boundaries. One of the main results of the paper is a constructive proof of the invariance of the coincident site lattice (CSL) under discrete relative displacements of the parent lattices (of possibly different kind) by a displacement shift complete lattice (DSCL) vector. In addition, we obtain necessary and sufficient conditions on two lattices, related by not only rotations but also lattice distortions, for the existence of a coincidence relation. We first apply these results to explore coincidence relations in arbitrary phase boundaries, and study interface dislocations. In particular, we demonstrate the framework for a phase boundary formed by a strained hexagonal lattice and a square lattice. As a second application, we show how to enumerate all possible (geometric) disconnection modes in arbitrary rational grain boundaries, including glide and non-glide modes in both STGBs and asymmetric-tilt grain boundaries (ATGBs). The constructive nature of the framework lends itself to an algorithmic implementation based exclusively on integer matrix algebra to construct all interfaces that admit CSLs up to a prescribed size, and determine disconnection modes in grain boundaries. We demonstrate the use of SNF bicrystallography on selected bicrystal misorientation axes/angles in face-centered cubic (fcc), body-centered cubic (bcc), and hexagonal (hex) lattices. [ABSTRACT FROM AUTHOR]

• The effects of TeO 2 on the sintering of c-Si solar cell are systematically studied. • TeO 2 affects the morphology of the grids on the sintering process of Ag pastes. • TeO 2 promotes Ag pastes sintering and improves the conductivity of Ag grids. • TeO 2 promotes the growth of the Ag nanocrystallites in Ag/Si contact interface. • An optimal conversion efficiency of solar cells was acquired at TeO 2 content ∼40%. Glass frits, as a critical ingredient, plays an important role between Ag electrode and crystalline silicon (c-Si) solar cells and determines sintering properties of the silver paste and contact quality with c-Si solar cells. Here glass frits with different contents of TeO 2 are prepared and used to investigate the sintering process and effects of contact quality of Ag pastes on c-Si solar cells. Microstructures and electrical properties of the Ag/Si contact interface and performances of the resultant c-Si solar cells are characterized systematically. The results show that TeO 2 promotes the growth of Ag nanocrystallites in the glass layer between Ag grids and c-Si wafers, thus reduces the contact resistance of the Ag grids and improves the contact quality of the Ag/Si interfaces. Moreover, TeO 2 improves the densification and conductive performances of the Ag grids. However, excessive TeO 2 has a negative effect on the conductivity of the Ag grid due to the increased thickness of the glass layer. Based on the competing factors played by TeO 2 , the conversion efficiency is the highest at an optimized TeO 2 content ∼40%. [ABSTRACT FROM AUTHOR]

The phase structure, residual stress, and thermal stability of CrAlN/SiN x multilayer films with different phase structures of a SiN x sublayer were studied. The crystal SiN x sublayer was transformed into an amorphous structure as the layer thickness increased from 0 to 1.7 nm. Multilayer films exhibited higher compressive residual stress and hardness than the monolithic CrAlN film, and the film with a 0.9 nm nanocrystalline-SiN x sublayer exhibited the highest value of −5.9 ± 0.2 GPa and 37.9 ± 2.5 GPa respectively. Phase transition was not detected in the nanocrystalline multilayer films, and the sublayer remained intact after vacuum annealing at 900 °C for 1 h. However, sublayer interface thermal dissolution in the film with a 1.7 nm amorphous SiN x sublayer resulted in a pitch-off effect at the grain boundary and the formation of w-AlN under the same condition. There was a slight decrease of hardness in all films after annealing and the film with a 0.9 nm nanocrystalline-SiN x sublayer still exhibited the highest hardness of 36.7 ± 3.7 GPa. Therefore, CrAlN/SiN x multilayer films with a crystalline interface are excellent candidates for achieving high thermal stability. • CrAlN/SiN x multilayer films were deposited by reactive magnetron sputtering. • Crystal and amorphous interfaces were achieved via adjusting the thickness of SiN x. • The microstructure, residual stress and hardness were affected by SiN x sublayer. • Crystal SiN x sublayer was beneficial to highest hardness and thermal stability. • Amorphous SiN x sublayer accelerated the decomposition of the multilayer film. [ABSTRACT FROM AUTHOR]

[Display omitted] Since the nuclear waste releases heat during the decay process, the mechanical behaviors of granites adjacent to the nuclear waste repository are inevitably impacted by the discrepancies in the thermal expansion characteristics of composite minerals. In this study, a mesostructure-based model (MSBM) was first proposed to characterize the thermal behaviors of varying minerals and cementation interfaces with consideration of the aperture-dependent weakening effects of pre-existing micro-cracks on mineral properties. Based on the MSBM, nine sets of numerical models with different mineral compositions were generated to explore the relationship between the mineral composition and the macro mechanical behaviors of granite at the temperatures of 25–250 °C. The meso -mechanisms behind the varied macro mechanical behaviors were comprehensively analyzed. The results indicate that the macro mechanical properties, i.e., the uniaxial compressive stress (UCS) and elastic modulus (E) are dependent on the combined effects of the different thermal expansion characteristics of minerals and the different thermoelastic behaviors of the crystalline interfaces, especially the quartz-biotite and quartz-feldspar mineral boundaries. Finally, an evaluation system aiming to quantify the effects of mineral composition and temperature on the mechanical behaviors of granite was proposed. Principal minerals such as quartz and feldspar strongly influence the UCS and E of the rock at different temperatures, and the influence of feldspar on UCS becomes more pronounced with increasing the temperature. Biotite has little influence on the change in elastic modulus with temperature, while the contribution of biotite to UCS varies with the temperature. [ABSTRACT FROM AUTHOR]

The exploration of germanium (Ge) detectors with amorphous Ge (a-Ge) contacts has drawn attention to the searches for rare-event physics such as dark matter and neutrinoless double-beta decay. The charge barrier height (CBH) of the a-Ge contacts deposited on the detector surface is crucial to suppress the leakage current of the detector in order to achieve a low-energy detection threshold and high-energy resolution. The temperature-dependent CBH of a-Ge contacts for three Ge detectors is analyzed to study the bulk leakage current (BLC) characteristics. The detectors were fabricated at the University of South Dakota using homegrown crystals. The CBH is determined from the BLC when the detectors are operated in the reverse bias mode with a guard-ring structure, which separates the BLC from the surface leakage current (SLC). The results show that CBH is temperature dependent. The direct relation of the CBH variation to temperature is related to the barrier inhomogeneities created on the interface of a-Ge and crystalline Ge. The inhomogeneities that occur at the interface were analyzed using the Gaussian distribution model for three detectors. [ABSTRACT FROM AUTHOR]

In the rapidly developing modern industrial fields, the materials used are often required to have simultaneously high strength and high electrical conductivity. However, these two properties often conflict and cannot be met at the same time. In the present study, we developed the Cu/Cu–Zr–Al bulk metallic glass (BMG) composites which exhibited simultaneously high strength and high electrical conductivity, as well as large plasticity. The BMG composites were fabricated by using spark plasma sintering crystalline Cu-coated Cu–Zr–Al metallic glass composite powders. The effect of particle size of the Cu–Zr–Al metallic glass powders on mechanical properties and electrical properties of the BMG composites was investigated systematically. Microstructure of contact interfaces between crystalline Cu and Cu–Zr–Al metallic glass was also characterized and discussed. This study is expected to provide an effective technical approach for the development of new high strength and high conductivity materials. [Display omitted] • The BMG composites with simultaneously high strength and high conductivity were developed. •The composites were fabricated by sintering Cu-coated Cu–Zr–Al glassy composite powders. •Effect of particle size on mechanical and electrical properties was investigated systematically. •Optimum Cu–Zr–Al metallic glass particle size of the BMG composites with both high strength and high conductivity was below 50 μm. •Good bonding between crystal and glassy is responsible for excellent comprehensive properties. [ABSTRACT FROM AUTHOR]

For industrial high-purity hydrogen production, it is essential to develop low-cost, earth-abundant, highly-efficient, and stable electrocatalysts which deliver high current density (j) at low overpotential (η) for oxygen evolution reaction (OER). Herein, we report an active mesoporous Ni 2 P @ FePO x H y pre-electrocatalyst, which delivers high j = 1 A cm−2 at η = 360 mV in 1 M KOH with long-term durability (12 days), fulfilling all the desirable commercial criteria for OER. The electrocatalyst shows abundant interfaces between crystalline metal phosphide and amorphous phosphorus-doped metal-oxide, improving charge transfer capability and providing access to rich electroactive sites. Combined with an excellent non-noble metal-based HER catalyst, we achieve commercially required j = 500/1000 mA cm−2 at 1.65/1.715 V for full water-splitting with excellent stability in highly corrosive alkaline environment (30% KOH). The alkaline-anion-exchange-membrane water-electrolyzer (AAEMWE) fabricated for commercial viability exhibits high j of 1 A cm−2 at 1.84 V with long-term durability as an economical hydrogen production method, outperforming the state-of-the-art Pt/C – IrO 2 catalyst. [Display omitted] • Noble-metal free catalysts for oxygen evolution reactions are investigated. • Crystalline (Ni 2 P) and amorphous (FePO x H y) phases in Ni 2 P @ FePO x H y catalyst provide more electrocatalytic active sites. • The Ni 2 P @ FePO x H y catalyst shows excellent AAEMWE cell performance with a low overpotential and good stability. • The Ni 2 P @ FePO x H y catalyst exhibits a low overpotential of 360 mV for OER to deliver a high current density of 1 A cm−2. [ABSTRACT FROM AUTHOR]

We investigate bulk and interface recombination in crystalline silicon with p-type fired passivating contacts. These consist of a chemical oxide and an in-situ doped layer of SiCx with low carbon content. Following a rapid thermal annealing to activate the dopants in the SiCx layer, we observe the formation of bulk defect states close to one of the band edges at temperatures between 450 and 700 °C. At temperatures of 800 °C and above, these bulk defects are increasingly cured. At the same time, the surface passivation provided by the interfacial oxide is increasingly deteriorated at temperatures above 800 °C, eventually permitting the injection of a recombination current into the SiCx layer. Consequently, there is a trade-off for the effective minority carrier lifetime with an optimum between 800 and 830 °C. We develop a formalism that distinguishes recombination through shallow bulk defects from the recombination current at the surface in a plot of the effective lifetime τ e f f over the ratio n / p. • Fireable rear side passivating contact. • Characterization and modelling of bulk and surface defects. • Understanding of the hydrogenation process. [ABSTRACT FROM AUTHOR]

[Display omitted] • MnO 2 /Mn 2 O 3 with amorphous/crystalline interface is facilely synthesized. • A multiple Mn ions redox-driven mechanism with triggered oxygen defects is proposed. • An evaluation criterion to rationally select anode to match cathode is presented. • Superior electrochemical performance is performed by MnO 2 /Mn 2 O 3 //MoS 2 device. Though tremendous efforts are devoted on structure engineering, most of Mn oxides show low capacity under wide work voltage actually caused by the limitation of sluggish reaction kinetics and inferior conductivity. Herein, we present an unprecedented self-improvement in electronic structure and Mn ions redox activity of MnO 2 /Mn 2 O 3 , carried out by a new mechanism of multiple Mn ions redox reaction with self-triggered oxygen-defect (Vo). It is disclosed that the MnO 2 /Mn 2 O 3 electrode mainly indicates capacitive-like surface redox reaction between Mn3+ and Mn4+ when operating within 0–1.2 V, which evolves into an adjustable multiple redox reactions of Mn2+, Mn3+ and Mn4+ accompanied with the self-generation of abundant Vo after changing the lower cut-off work potential (LCWP) from 0 to −0.3 V. Theoretical and experimental results demonstrate the rich Vo in active structure induces new electronic states and electron redistribution between Mn and O, which increase total charge storage more than two-folds to 786. 7 C g−1 (1 A g−1) by promoting multiple Mn ions redox reactions. During assembling MnO 2 /Mn 2 O 3 -based pseudocapacitor, a designed four-electrode system reveals fast reaction kinetics of anode assigns MnO 2 /Mn 2 O 3 with more wide effective work potential, guiding the effective enhancement of energy density by selecting MoS 2 as the anode. [ABSTRACT FROM AUTHOR]

Amorphous/crystalline heterophase composites possess expansive reaction interfaces and abundant oxygen vacancy defects, providing novel electron-hole transmittal mode and significantly facilitating the surface adsorptions and redox reactions. Herein, galvanic replacement reaction (GRR) was used to construct amorphous SnO x / crystalline Co 3 O 4 multishell heterostructures. Characterizations indicated the continuous transition from Co 3 O 4 to amorphous SnO x on each shell, generating abundant amorphous/crystalline interfaces. Moreover, the oxygen vacancy defects concentration also increased with the GRR proceeding. Benefitting from theses, the surface oxygen adsorption was facilitated due to more surface active sites and enhanced carrier densities. However, with further increasing the reaction time, decreased adsorbed oxygen concentrations were detected, owning to the unexpected high potential barriers induced by excessive heterojunctions. Gas sensing results showed that the sensors with 1 h GRR exhibited the best sensing performance with an exceptional response (1268) to 100 ppm formaldehyde gas and low detection limit (21 ppb) at low working temperatures (100 °C). The synergistic effects between oxygen vacancy defects and amorphous/crystalline heterophase interfaces on the superior gas sensing behaviors were also investigated. Most importantly, results presented will shed lights on the rational design of highly sensitive gas sensors through amorphous/crystalline interfaces constructions. [Display omitted] Amorphous SnO x /Co 3 O 4 multishell with abundant oxygen vacancy defects and amorphous/crystalline interfaces exhibits remarkable formaldehyde sensing performance. • Amorphous SnO x was transformed on crystalline Co 3 O 4 multishell with a galvanic replacement reaction. • Abundant oxygen vacancies and amorphous/crystalline heterophase interfaces were detected. • CoSn1 sensor exhibited superior HCHO sensing response and low detection limit at low temperature. • The superior sensing behavior owns to the oxygen vacancy and amorphous/crystalline interface. [ABSTRACT FROM AUTHOR]

[Display omitted] • Innovative passivating contact using poly-Si/quantum well/c-Si contact. • Quantum well suppresses dopant diffusion from the poly-Si layer into c-Si bulk. • Excellent passivation quality achieved with iV oc of 742 mV and J o of 1.1 fA/cm2. Herein, we propose a quantum well comprising a stack of SiO x /nanocrystalline silicon (nc-Si)/SiO x layers between a polycrystalline silicon (poly-Si) layer and a crystalline silicon wafer (c-Si) for enhancing the passivation quality through the poly-Si/c-Si passivating contact for c-Si solar cells. A large number of dopants can diffuse deeply into c-Si from a heavily doped poly-Si layer during high-temperature annealing, reducing the surface passivation quality. The quantum well with the double SiO x layer plays a significant role as a double barrier, thus suppressing this. The formation of the nc-Si phase sandwiched between the SiO x layers can support carrier transport, i.e., the tunnelling of carriers through the SiO x layers for collection. Moreover, a highly doped poly-Si/quantum well/c-Si contact exhibits considerable improvement in the passivation quality, achieving a high iV oc of 742 mV and low J o of 1.1 fA/cm2, compared with a reference poly-Si/c-Si passivating contact (iV oc = 707 mV, J o = 32.5 fA/cm2). The results indicate the effectiveness of the innovative passivating contact concept and pave the way for further improvements in the performance of c-Si solar cells. [ABSTRACT FROM AUTHOR]

• PbSe is strongly tensile strained at room temperature when grown on GaAs(1 0 0) and GaAs(1 1 1)B. • The film-substrate interface is highly abrupt in both cases. • Tensile strain increases the energy gap of PbSe by about 10% of its bulk value, at room temperature. Thin films of PbSe have been synthesized by molecular beam epitaxy on both GaAs(1 0 0) and GaAs(1 1 1)B substrates. Despite the smaller lattice constant of GaAs, the PbSe layers are (0 0 1)-oriented and undergo in-plane tensile strain on both substrates due to the thermal expansion coefficient mismatch between the materials. High resolution transmission electron microscopy observations reveal an abrupt and highly crystalline interface, not impacted by the tensile strain. The impact of strain on the electronic band structure is computed and found to induce an increase in the energy gap by as much as 10%. [ABSTRACT FROM AUTHOR]

It was well known that the defects in the polymer chains could significantly influence the crystallization process of semi-crystalline polymers. In this work, the role of defect distribution in the melt memory effects was studied by comparatively investigating a pair of Ziegler-Natta and metallocene-made isotactic polypropylene (ZN-iPP and M-iPP) fraction specimens with the same total defect content which were obtained from two raw parent samples through the solvent extraction. The characterization results of melting behaviors, polymorphic structures, and the successive self-nucleation and annealing analysis demonstrated that these two fractions exhibited the different distribution of defects, i.e. , the defect distribution in the M-iPP specimen was random while that in the ZN-iPP specimen was nonstatistical. The results of self-nucleation (SN) experiments indicated that the M-iPP exhibited much wider temperature range of Domain II than the ZN-iPP with similar total defect content, which indicated that the M-iPP showed a much stronger melt memory effect. Considering the effect of the microstructure on the crystallization behavior and the sequences containing defects could be excluded from the crystalline regions during the formation of crystal, we speculated that the random distributed defects in M-iPP could form a continuous interface between the crystalline regions and amorphous phase which could cause a heterogeneous melt and strengthen the melt memory effect. [Display omitted] • Defect distribution influenced the melt memory effect of iPP. • The defect in M-iPP was random while that was nonstatistical in ZN-iPP. • The M-iPP with random distributed defects exhibited stronger melt memory effect. [ABSTRACT FROM AUTHOR]