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To date, the application of additive manufacturing techniques in fabricating SiAlON ceramics with intricate geometries has been limited. This investigation demonstrates the synthesis of SiAlON ceramics by integrating silicon nitride (Si 3 N 4) powders with variable proportions of aluminum nitride (AlN) utilizing the vat photopolymerization (VPP) approach. The effects of AlN content on the properties of SiAlON ceramic slurries, green bodies, and sintered parts were systematically investigated. Notably, the slurry's viscosity decreases progressively with an increase in AlN, aligning with VPP printing prerequisites. Additionally, the curing depth of the slurry enhanced proportionally with AlN augmentation, elevating from 21 μm to 44 μm at an energy exposure of 800 mJ/cm2, with the pivotal addition being 15 vol% AlN, where optimal properties were achieved. The zeniths of flexural strength, bulk density, relative density, and thermal conductivity were recorded at 385.66 ± 22.63 MPa, 3.34 ± 0.09 g/cm3, 96.22 ± 2.55 %, and 37.4 ± 0.31 W m−1 K−1, respectively. The fabrication of SiAlON ceramics with complex configurations was successfully realized, heralding a novel methodology for future SiAlON ceramic production. [ABSTRACT FROM AUTHOR]

The advancement of efficient and stable inverted CsPbI 2 Br perovskite solar cells (PSCs) is imperative for their unique advantages of eliminating detrimental dopants and enabling compatible processes with tandem cells in comparison with the regular structures. However, the progress of this structure lags due to its relatively low open circuit voltage (V oc). Herein, we present an effective surface passivation strategy using phenethylammonium iodides with a different side group to ameliorate the aforementioned issues. It has been observed that 4-methyl phenethylammonium iodide (MePEAI) with the –CH 3 side group can effectively reduce the trap density of the perovskite film by forming interactions with the under-coordinated Pb2+ ions, thereby suppressing the nonradiative recombination. Additionally, this approach optimizes the energy-level alignment at the perovskite/PCBM interface. As a result, the optimized device demonstrates a substantially enhanced efficiency from 11.23 to 14.10 %. Furthermore, the MePEAI-treated device exhibits excellent long-term stability. The unencapsulated device retains 81.2 % of its initial power conversion efficiency (PCE) after being stored for over 2900 h in an N 2 atmosphere. [Display omitted] TOC GRAPHICS. [ABSTRACT FROM AUTHOR]

Three coatings including topcoat-free NiCoCrAlYHfZr bond coat and the thermal barrier coating (TBC) system consisting of an 8 wt% Y 2 O 3 stabilized ZrO 2 (8YSZ) topcoat and either a NiCoCrAlYHfZr or a NiCoCrAlY bond coat were prepared in this study. The localized enrichment of Hf-rich precipitations within NiCoCrAlYHfZr bond coat was significantly alleviated after the YSZ deposition, instead, the nano-sized HfO 2 precipitations formed and linearly distributed along the initial thermal grown oxide (TGO)/bond coat interface. Cyclic oxidation behaviors of the three coatings were evaluated at 1100 °C. The results showed that a uniform TGO with fine reactive elements (REs)-rich inclusions was generated in YSZ-NiCoCrAlYHfZr TBC system, alleviating the negative effects resulted from the localized enrichment of Hf-rich precipitations. Besides, co-doping HfZr in NiCoCrAlY bond coat prevented the formation of spinel since HfZr segregating at Al 2 O 3 grain boundaries inhibited the outward diffusion of Ni, Co and Cr from the bond coat, thus significantly improving durability of the TBC system. [ABSTRACT FROM AUTHOR]

The calcium fluoride (CaF 2) component has excellent light transmission and a high laser damage threshold in the UV band, and thus is a potentially ideal material for high-power laser facility. However, the low-damage surface is difficult to attain via the existing processing technologies due to its brittleness, especially the dissociation property of the (111) surface. We innovatively propose H 2 O(g) plasma-assisted porous diamond abrasive lapping technology to achieve low-damage and high-precision surface processing of CaF 2 component, which means that the CaF 2 component is modified first and then the softened modified layer is removed by the porous diamond abrasive lapping. The H 2 O(g) plasma modification mechanism was elucidated through a combination of molecular dynamics simulation and experiment and comparison with H 2 O(g) plasma etching. The modification layer including an oxide layer and a phase change layer was produced by adjusting the plasma processing process (power of 25 W and H 2 O(g) content of 10 ml). Then the modified CaF 2 component was lapped by the porous diamond abrasive tool on the ductile domain layer which is more than the modified layer and less than the sum of the modified layer and plastic domain. When the lapping process parameters were 200 rpm platen rotation speed and 20 N lapping pressure, a surface accuracy of 15.34 nm PV, 2.29 nm RMS (φ1 mm) was obtained. This study provides technical support for the low-damage processing of CaF 2 component. [ABSTRACT FROM AUTHOR]

Lanthanum borate-based glass-ceramic has recently received considerable attention in the field of high-frequency communications as a sintering aid, due to the low sintering temperature and the precipitation of crystalline phases with excellent dielectric and mechanical properties. Importantly, the densification and crystallization behaviors of glass-ceramic are not only determined by its composition, but also affected by various processing parameters, such as the initial particle size, which is rarely explored for optimizing the dielectric and mechanical properties of lanthanum borate-based glass-ceramic/ceramic composites. Herein, La 2 O 3 –B 2 O 3 –CaO–P 2 O 5 –SiO 2 (LBCPS) glass-ceramics with a series of initial particle sizes are achieved by ball milling method through controlling the milling time. Employing LBCPS glass-ceramics with different particle sizes as the sintering aid, various LBCPS/Al 2 O 3 composites are fabricated, and the dielectric and mechanical properties of which are further investigated. Notably, the LBCPS/Al 2 O 3 composite with a moderate glass-ceramic particle size of 2.7 μm exhibits the excellent comprehensive performance with a low dielectric loss of 8.6 × 10−4 at 9.8 GHz and a high flexural strength of 199 MPa. Moreover, the influencing mechanisms of the glass-ceramic particle size on the crystallization, microstructure, and densification of the LBCPS/Al 2 O 3 composite have also been systematically explored and proposed. This research work provides an intriguing strategy for optimizing the dielectric and mechanical properties of the glass-ceramic/ceramic as the high-performance low-temperature co-fired ceramic (LTCC) substrate. [ABSTRACT FROM AUTHOR]

Single-source-precursor derived ceramics exhibit advantages for the preparation of Si-based ceramics with controllable phase composition and adjustable functional/mechanical properties, which has significant potential for (ultra)high temperature ceramic materials. Within the present work, a series of hafnium/boron-containing Si 3 N 4 -based ceramics (SiHfBCN) are prepared upon pyrolysis/annealing of the corresponding single-source-precursors in N 2 atmosphere at different temperatures ranging from 1000 °C to 1700 °C. The high-temperature (micro)structural evolution with respect to the annealing temperatures and boron concentration was studied using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. The results show that the amorphous SiHfBCN ceramics convert upon crystallization into ceramic nanocomposites consisting of a α-Si 3 N 4 matrix with embedded Si, HfB 2 , and HfB x C y N 1– x – y. The formation and stability of HfB x C y N 1– x – y solid solution were discussed in detail. Finally, the oxidation resistance of the obtained α-Si 3 N 4 /HfB 2 /HfB x C y N 1– x – y ceramic nanocomposites was investigated by thermal gravimetric analysis in air. [ABSTRACT FROM AUTHOR]

In this work, novel highly efficient cyan-emitting Ce3+-activated CaLu 2 HfGaAl 3 O 12 (abbreviated as CLHGAO) garnet-structured phosphors were synthesized using the high-temperature solid-state reaction route. Rietveld refinement results demonstrate the as-prepared samples belong to cubic space group Ia 3 ‾ d. These CLHGAO: x Ce3+ (x = 0.5–8%) phosphors possessed a broad absorption band in the 320–450 nm wavelength range with a maximum at 408 nm. Upon 408 nm excitation, the CLHGAO:0.5%Ce3+ sample showed a broad cyan emission band within 425–750 nm wavelength range (emission peak: 493 nm; bandwidth: 95 nm), along with CIE color coordinates of (0.1939, 0.3533) and a high internal quantum efficiency of 81.9%. It is observed that, with increasing Ce3+ doping concentration from 0.5% to 8%, the emission peak position of CLHGAO: x Ce3+ moves from 493 nm to 527 nm, and the corresponding emission color changes from cyan to green. Besides, the thermal stability and color stability of CLHGAO:0.5%Ce3+ phosphor at high temperature are also studied. A white LED device was fabricated by utilizing a 395 nm LED chip with as-prepared CLHGAO:0.5%Ce3+ cyan-emitting phosphor and commercial (Ba,Sr) 2 SiO 4 :Eu2+ green-emitting phosphor and commercial CaAlSiN 3 :Eu2+ red-emitting phosphor, and it demonstrates a high-color-quality white light with high color rendering index of 91, low color correlated temperature of 3547 K and good luminous efficacy of 58.71 lmW−1. [ABSTRACT FROM AUTHOR]

Niobium carbide composite coatings with Nb 2 C, NbC, Nb 3 Si as the main phases were prepared in situ on the surface of TC4 titanium alloy by plasma spraying Nb–SiC composite powder. The microstructure of the coating was characterized in detail by TEM, and the reaction mechanism of Nb–SiC was revealed. Sub-micron and nano-scale NbC grains dispersed in Nb 3 Si region, nano-Nb/Nb 3 Si cellular eutectic region, and equiaxed Nb 2 C nanograins region were formed in the coating. The research results show that Nb and SiC reacted firstly to form cubic NbC and Nb 3 Si phases during the plasma spraying process. Then, NbC with a higher melting point took the lead in crystallization during the cooling process of the coating, forming sub-micron and nano-scale NbC granular fine grains. Nb 3 Si with a lower melting point crystallized around the sub-micron and nano-scale NbC granular fine grains in the subsequent cooling process. In the plasma spraying process, the molten droplets formed Nb/Nb 3 Si cellular eutectic structure under large temperature gradient and extremely fast cooling rate. The remaining Nb in the raw material powder formed a diffusion couple with NbC to generate fine and dispersed nano-equiaxed Nb 2 C with cubic structure. The present investigation provides a reference for the reaction synthesis of advanced nanocomposites using Nb–SiC system. [ABSTRACT FROM AUTHOR]

As 5G technology advances, so does the prevalence of harmful electromagnetic waves, and as a result, researchers have been progressively interested in developing materials that can absorb microwaves. So, it's become desirable to fabricate unique microwave absorbent materials (MAMs) to mitigate the negative effects of electromagnetic radiation and offer protection to biological beings and electronic data. Herein, we fabricated a novel HoFeO 3 @WSe 2 @SiO 2 composite via the co-precipitation method. The microwave absorption properties of the HoFeO 3 ,WSe 2 , SiO 2 and HoFeO 3 @WSe 2 @SiO 2 (with 25, 35 and 45 wt% loading) were examined in the X-band frequency range. 35 wt% filler loading shows reasonable reflection loss values with the broadest effective absorption bandwidth (EAB). The optimum impedance matching is responsible for the enhanced microwave absorption performance of the HoFeO 3 @WSe 2 @SiO 2 with 35 wt% filler loading. In addition, the best sample is measured using both waveguide and free-space techniques and the results have been compared. The free-space method has been demonstrated to be an effective alternative testing strategy due to its contact-free and non-destructive features. Furthermore, the technique described in this study to design innovative HoFeO 3 @WSe 2 @SiO 2 microwave absorbers can offer significant assistance with a wider absorption band. In this context, HoFeO 3 @WSe 2 @SiO 2 is expected to be used as a highly efficient microwave absorbent. [ABSTRACT FROM AUTHOR]

Advanced high-performance microwave absorber development now revolves around achieving better microwave absorption performance and intelligent electromagnetic property control. Effectively adjusting electromagnetic microwave dissipation qualities throughout a wide frequency range has been mostly unexplored, particularly for manufactured absorbers. Innovative and high-performance absorber materials are produced and analyzed in this study. Solvothermal preparation is used to synthesize polygonal-shaped CuCo 2 S 4 particles that are embellished with Cu 2 S particles. The permittivity and permeability of polygonal CuCo 2 S 4 particles decorated with Cu 2 S particles are significantly altered, which further affects the nanocomposite's performance in terms of microwave absorption. At a filler loading of 40 wt percent, the composite exhibits exceptional microwave absorption capabilities, and at a thin thickness of 1.5 mm, its effective absorption bandwidth (EAB) approaches 4.5 GHz, covering the whole X-band frequency range. The produced composite has outstanding dissipation qualities owing to the synergistic effects of numerous attenuation mechanisms and hetero-interfaces, where the ideal microwave dissipation strength is up to −32 dB. [ABSTRACT FROM AUTHOR]

Understanding the elemental and structural evolution from green fibers to inorganic fibers is important for fabricating high-performance ceramic fibers via the polymer-derived ceramics (PDCs) route. In a previous study, we found a novel polyborazine precursor, poly[2-propylamino-4,6-bis(methylamino)borazine- co -tri(methylamino)borazine] (PPMAB), which possesses a high ceramic yield and outstanding spinnability. Herein, we provide an insight into the evolution process from PPMAB to inorganic BN fibers. During the curing process, NH 3 only reacted with the B–NHCH 3 groups in PPMAB to form B–NH 2 groups, which further reacted with B–NHCH 3 to form B–NH–B bridges. Therefore, crosslinked networks were formed in the cured fibers and the gel content increased from 52.3 to 92.1 wt%. In the nitridation process, NH 3 not only reacted with unreacted B–NHCH 3 but also reacted with B–NHCH 2 CH 2 CH 3 groups to form B–NH 2 groups, which reacted with N–CH 3 bridges in the adjacent PPMAB molecule to form –N(B 3 N 3) 3 - networks. Simultaneously, CH 3 NH 2 and CH 3 CH 2 CH 2 NH 2 escaped from the fibers, and the carbon content of the fibers was reduced from 20.588 wt% to 0.115 wt%. By controlling the curing and nitridation processes, the curing degree can be enhanced, whereas the pore defects resulting from gas molecular escape can be effectively reduced. Thus, dense inorganic BN fibers with excellent dielectric properties (2.33 < ε < 2.5, tan δ < 3.4ⅹ10−3) and high tensile strength (1.6 GPa) were fabricated. The present study not only provides ideas for the design and synthesis of polyborazine precursors, but also for the fabrication of high-performance BN fibers. [ABSTRACT FROM AUTHOR]

We fabricated reduced graphene oxide (rGO)-reinforced Al 2 O 3 composites by spark plasma sintering and studied the effect of graphene oxide (GO) dimensions on the microstructure and mechanical properties of composites. The thin GO led to both grain size refinement and grain boundary pinning effects. The Al 2 O 3 composite reinforced by thin and large GO had higher hardness than that reinforced by thick and small GO. The addition of thick GO leads to a reduction of hardness and generation of lateral cracks at the Al 2 O 3 grain boundaries under indentation due to low rGO interlayer strength. The rGO distribution in the Al 2 O 3 matrix was studied. A model calculation showed that the spacing between two parallel rGO platelets was one Al 2 O 3 grain at rGO addition of 0.77 wt%. We concluded that the increased hardness of rGO/Al 2 O 3 composites is due to the fine grain size and thin rGO at Al 2 O 3 grain boundaries. [ABSTRACT FROM AUTHOR]

High-performance and low-carbon MgO–C refractories are important refractories for smelting ultra-low carbon steel and clean steel. Based on this, Cr 3 C 2 /C composite powders were synthesized by the molten-salt method, and used as an additive to prepare low-carbon MgO–C refractories under nitrogen atmosphere. The phase, morphology and oxidation kinetics of Cr 3 C 2 /C composite powders were studied. In addition, the effect of Cr 3 C 2 /C composite powders on the morphology, mechanical properties, thermal shock resistance, and corrosion resistance of MgO–C refractories was investigated. The results indicated that the Cr 3 C 2 /C composite powders exhibited superior oxidation resistance than flake graphite. Moreover, the Cr 3 C 2 /C composite powders were introduced into the MgO–C refractories. Compared with the sample without Cr 3 C 2 /C composite powders, the introduction of 1 wt% Cr 3 C 2 /C composite powders significantly improved the thermomechanical properties and corrosion resistance of the material, its CMOR, CCS before and CCS after thermal shock were 9.06 MPa, 50.40 MPa and 32.60 MPa, respectively, and the corrosion index was significantly reduced from 44.6% to 26.5%. [ABSTRACT FROM AUTHOR]

Employed ubiquitously in oral restorations, zirconia-based bioceramics face challenges with low-temperature degradation (LTD) in the tetragonal phase (t-ZrO 2) within oral environments. In order to improve the resistance of ZrO 2 ceramics to LTD, this study utilized vat photopolymerization technology to prepare 7Ce3Y–ZrO 2 (7 mol% CeO 2 and 3 mol% Y 2 O 3). By adjusting the dispersant content and photosensitive resin ratio enabled the attainment of a 63.5 μm curing depth with a 400 mJ/cm2 exposure, meeting the requirements for vat photopolymerization printing. After sintering at 1550 °C, these ceramics shown a relative density of 97.84 % and an impressive flexural strength of 503.1 MPa. Accelerated LTD tests were conducted to assess LTD-resistance, revealing no degradation in mechanical properties or evidence of tetragonal to monoclinic phase transitions. This stability is credited to the cerium ions' efficacy in hindering oxygen vacancy formation and subsequent aging within the ZrO 2. This study affirms that CeO 2 –Y 2 O 3 co-stabilized ZrO 2 ceramics prepared using vat photopolymerization technology exhibit outstanding properties and resistance to LTD, showcasing significant potential in the field of oral restoration. [ABSTRACT FROM AUTHOR]

Within the present work, a series of spinel-structured (MnFeCoNiX) 3 O 4 (X = Zn, Cu, Cr) high entropy oxides (HEOs) were fabricated by co-precipitation method and the subsequent heat treatment. The phase composition, microstructure, thermal stability, magnetic property and electromagnetic (EM) wave loss ability were comprehensively studied. It is found that spinel-structural (MnFeCoNiX) 3 O 4 HEOs are well-crystallized at above 800 °C with a space group Fd-3m. Morphological analysis reveals that grains of different HEOs contain nano-domains with particle sizes between 100 nm and 500 nm. In addition, Mn, Ni, Co, Fe, Zn, Cr and Cu elements are homogeneously distributed and the chemical states of Mn, Ni, Co and Fe are all +2 and + 3, while Cu only exists in +2 state. Thermal stability analysis shows that (MnFeCoNiCu) 3 O 4 HEO is able to keep stable at 1000 °C. Moreover, the (MnFeCoNiCu) 3 O 4 sample exhibits the best magnetic properties and EM microwave loss ability in comparison with (MnFeCoNiZn) 3 O 4 and (MnFeCoNiCr) 3 O 4. For (MnFeCoNiCu) 3 O 4 , the values of saturation magnetization (M s) and coercivity (H c) are 38.6 emu/g and 52.6 Oe, respectively. Meanwhile, (MnFeCoNiCu) 3 O 4 displays a minimum reflection loss (RL) of −15.5 dB at 8.48 GHz with a thickness of 4.5 mm and a wide effective absorption bandwidth (EAB) of 8.84 GHz with the sample thickness of 5 mm. It is expected that the excellent high-temperature stability and good EM wave absorbing performance of high entropy (MnFeCoNiCu) 3 O 4 could make it potentially useful in EM wave absorption under elevated temperatures. [ABSTRACT FROM AUTHOR]

A novel MoSi 2 –Al 2 O 3 composite coating was prepared on Mo-based TZM alloy by slurry sintering method. The oxidation behavior of the coating was evaluated at 1600 °C in static air. Microstructure and phase composition of the as-prepared and oxidized coatings were characterized, and the antioxidant mechanism of the coating at high temperature was discussed. A three-layer structure was observed in the as-prepared coating, consisting of a ∼2 μm thick Mo 5 Si 3 diffusion layer, a ∼65 μm thick MoSi 2 inner layer and a ∼36 μm thick outer layer of mixture of MoSi 2 and Al 2 O 3. After oxidation at 1600 °C for 5 h, all MoSi 2 phases were completely converted to intermediate silicide Mo 5 Si 3 by solid-state diffusion, and the formed Mo 5 Si 3 phase would be transformed into Mo 3 Si phase with further extending the oxidation time. Furthermore, a dense oxide layer of SiO 2 -mullite was formed on the specimen surface, which can effectively protect the material to further oxidation. The MoSi 2 –Al 2 O 3 coating could protect the substrate effectively at 1600 °C for 20 h without failure. The enhanced oxidation resistance of MoSi 2 –Al 2 O 3 coating is due to the formation of multi-layer structure containing a SiO 2 -mullite composite oxide outer layer with high thermal stability and low oxygen permeability. [ABSTRACT FROM AUTHOR]

Ta-doped Bi 3.25 La 0.75 Ti 3 O 12 (BLTT)/ZnO films were fabricated on Pt(111)/Ti/SiO 2 /Si substrates by a magnetron sputtering method. Firstly, ZnO crystal thin films were grown on the substrates by a reactive sputtering method. Then, BLTT thin films were deposited on the ZnO layers at room temperature and post-annealed at 600 °C. The micromorphology, ferroelectric and dielectric properties of BLTT/ZnO films were analyzed. The XRD analysis shows that ZnO buffer layer significantly reduces the crystallization temperature of BLTT thin film. The TEM results show that lamellar BLTT grains are grown on ZnO layer at a certain angle with few elements diffusion at the interface of ZnO phase and Bi 4 Ti 3 O 12 phase. The ferroelectric properties indicate that BLTT/ZnO films exhibit different remanent polarization and coercive fields under electric field with different directions. The novel mechanism of tailoring ferroelectric properties may open new possibilities for designing special ferroelectric devices. [ABSTRACT FROM AUTHOR]

Electromagnetic wave (EMW) absorbing materials have excellent potential for various applications in civil engineering and the military. In this study, siliconboron carbonitride (SiBCN) ceramics with excellent EMW absorption capability and oxidation resistance were obtained by adjusting the boron content. The results revealed that the graphite crystallite size in the SiBCN ceramics increased from 3.42 to 3.78 nm, whereas the thickness of the oxide layer decreased from 16.6 to 8.2 μm. The highest electrical conductivity and permittivity for the SiBCN ceramics were obtained when the boron content was 5%. The minimum reflection loss was −35.25 dB at 10.57 GHz and a ceramic thickness of 2.0 mm. At a temperature of 600 °C, the SiBCN ceramic exhibited excellent EMW attenuation ability; particularly, the minimum reflection loss reached −29.18 dB at 9.65 GHz and a ceramic thickness of 2.5 mm. The superior EMW absorption properties of the SiBCN ceramics at high temperatures can be ascribed to the synergistic effect of relaxation and conductivity. The results suggest that boron could enhance the transformation of amorphous carbon into crystalline graphite and increase the number of heterointerfaces and conductive paths. This work provides a method for obtaining SiBCN ceramics with excellent EMW absorption properties. Therefore, the electrical conductivities of the ceramics increased with increasing temperature as both the migration and hopping conductances increased with increasing temperature. Additionally, the increase in temperature enabled the electrons to leap from the valence band into the conduction band, which also improved the electrical conductivity. [ABSTRACT FROM AUTHOR]

A one-step hydrothermal treatment was used to deposit a nano silver-loaded magnesium-aluminum hydrotalcite (Ag/Mg-Al) layered double hydroxide (LDH) coating onto the surface of a Mg-Zn-Ca alloy to improve the corrosion resistance and antibacterial properties of magnesium alloys for biomedical applications. The effect of experimental parameters such as temperature and time on the microstructure, compositions, and corrosion resistance of the Ag/LDH coating during the hydrothermal treatment was investigated to optimize the preparation process. Additionally, the in vitro degradation performance, antibacterial performance and biocompatibility of the coating were evaluated to determine the optimal preparation condition. The results show that when the LDH–NO 3 – coating is prepared at 110 °C for 10 h, the constituting silver particles (dimensions, 10–30 nm) are obtained, while the corrosion current density and the corrosion rate decrease to 4.41 μA/cm2 and 0.27 mm/year, respectively. The antibacterial experiment demonstrates that the coating effectively inhibits the reproduction of Escherichia coli while offering remarkable biocompatibility. [ABSTRACT FROM AUTHOR]

TiO 2 –ZnO/Au ternary heterojunction nanocomposite was fabricated by producing TiO 2 nanosheets first using solvent-thermal method followed by Au deposition and ZnO deposition respectively. The TiO 2 nanosheets provide a relatively large surface area for the good dispersion of ZnO nanoparticles and Au particles and sufficient contact with the medium, which contribute to the excellent photocatalytic performances of TiO 2 –ZnO/Au heterojunction composite. The phases and structures, morphologies, surface and optical properties of the ternary heterojunction composite are well-characterized. Subsequently, the photocatalytic hydrogen generation of TiO 2 –ZnO/Au is evaluated under visible light irradiation. TiO 2 –ZnO/Au ternary heterojunction composite has efficient light absorption ability and excellent performances in photocatalytic hydrogen generation (1068 μmol/g under the irradiation of visible light for 4 h) and antibacterial properties (reaching 98.2%). TiO 2 –ZnO/Au ternary heterojunction nanocomposite has a large potential to be used in areas such as interior wall coating. [ABSTRACT FROM AUTHOR]

Stereolithography(SLA) combined with reactive melt infiltration (RMI) is an effective way to fabricate silicon carbide(SiC) ceramic components with complex shapes and high precision. The purpose of this paper is to increase the content of SiC in the sintered body and improve the properties of SiC ceramics prepared by SLA/RMI technologies by the impregnation of the precursor of carbon source after debinding. The effects of the concentration of phenolic resin solution on the strength of sintered body were studied. The results show that this method can reduce the coefficient of thermal expansion and improve the thermal conductivity of the final body. At the same time, when the concentration of phenolic resin solution is 40 wt%, the final body obtained the best comprehensive properties. The value of bulk density, flexural strength and elastic modulus were 2.89 g/cm3, 244.17 ± 5.13 MPa and 402.39 GPa, respectively. This strategy provides a promising prospect for the preparation of space optical mirrors with complex shapes and high strength by the SLA/RMI method. [ABSTRACT FROM AUTHOR]

Niobium carbide composite coatings were prepared on titanium alloy surface by plasma spraying NbC–Al 2 O 3 , Nb–SiC and Nb–SiC–Al composite powders, respectively. The phase composition, microstructure and formation mechanism of the three composite coatings were analyzed and their microhardness, toughness and scratch resistance were compared. The phases of the NbC–Al 2 O 3 system did not change during the plasma spraying process, and new phases (Nb 2 C, NbC and Nb 3 Si) were formed in the Nb–SiC and Nb–SiC–Al systems. TEM results of the Nb–SiC composite coating indicate that the new phases nanocrystalline Nb 2 C, submicron NbC and nanocrystalline Nb 3 Si were formed during the plasma spraying process. Compared with the NbC–Al 2 O 3 composite coating, the microstructure of the Nb–SiC and the Nb–SiC–Al composite coatings were uniform, and the porosity were relatively low, and the hardness was higher. The Nb–SiC–Al composite coating was denser than the Nb–SiC composite coating, the lamellar structure was obvious and the number of pores in the coating was the least, which is attributed to the better molten state of the composite powder by the addition of the Al to the Nb–SiC system. The Nb–SiC–Al composite coating had better toughness and scratch resistance. [ABSTRACT FROM AUTHOR]

In this study, Ti–Si–C composite coatings were synthesized via plasma spraying of agglomerated powders prepared by a spray drying/precursor pyrolysis technology using Ti, Si, and sucrose powders. The influence of Si content, ranging from 0 wt% to 24 wt%, on the microstructure, mechanical properties, and oxidation resistance of the composite coatings was investigated. Results show that the phase composition of the Ti–Si–C composite coatings changes with the increasing Si content. The coatings without Si addition consist of TiC and Ti 3 O; the coatings with 6–18 wt% Si are composed of TiC, Ti 5 Si 3 , and Ti 3 O; the coatings with Si content of 24 wt% form only TiC and Ti 5 Si 3 phases. As the Si content increases, the hardness of the Ti–Si–C composite coatings increases first and then decreases, depending on the intrinsic hardness of the ceramic phases, the brittleness of Ti 5 Si 3 , and the defects such as pores and cracks. The Ti–Si–C composite coatings have high wear resistance due to the in-situ synthesized high-hardness TiC and Ti 5 Si 3. Owing to the high brittleness of Ti 5 Si 3 , the increasing Si content leads to higher wear volume loss at room temperature, which can be partially improved in high-temperature wear tests. The oxidation resistance of Ti–Si–C composite coatings increases with the increase of Si content, and the higher the oxidation temperature, the more obvious the influence of the Si addition on oxidation resistance. [ABSTRACT FROM AUTHOR]

This study investigates the preparation of TiO 2 –SiO 2 –CaCO 3 composite opacifier (Ti–Si–Ca) and its application in sanitary ceramic glazes. This approach involved hydrophobic agglomeration through surface-induced hydrophobic modification of TiO 2 , SiO 2 and CaCO 3 particles, along with the interactions between the hydrophobic carbon chains of modifiers. The Ti–Si–Ca formed a uniform coating with well-dispersed TiO 2 and SiO 2 particles on the CaCO 3 surface and strong bonds formed among TiO 2 , SiO 2 and CaCO 3 through interpenetration of the organic carbon chains on the surface. The Ti–Si–Ca was added to the basic glazes of sanitary ceramics at a proportion of 15.5 % and fired at 1125 °C for 4 h. The resulting white ceramic glazes had chromaticity values of L*, a*, and b* at 93.76, −0.73, and 3.89, respectively, demonstrating superior glaze opacity and whiteness compared to glazes made with a ZrSiO 4 opacifier (L* 90.30, b* 4.50). Glass and titanite phase make up the majority of the Ti–Si–Ca ceramic glazing layer of, with titanite serving as the opacified phase. Elimination of organic groups in Ti–Si–Ca during glaze firing formed interfacial chemical bonds among TiO 2 , SiO 2 and CaCO 3 , which facilitated the synthesis of titanite from the three components at high temperatures. The Ti–Si–Ca was a highly opaque glaze without yellowing because the organic groups of Ti–Si–Ca were removed and interfacial chemical bonds formed among the TiO 2 , SiO 2 and CaCO 3 in the low-temperature stage of glaze firing. This transformed the three phases into titanite at high temperature and eliminated free TiO 2. The formation of rutile TiO 2 , which has a yellow hue, at high temperatures was inhibited. This study provides a novel approach for low-energy preparation of TiO 2 –SiO 2 –CaCO 3 composite opacifiers and addresses the challenge of replacing ZrSiO 4 with TiO 2 in ceramic opacifiers. [ABSTRACT FROM AUTHOR]

To preserve the structural and interfacial integrity of diamond, diamond/SiC composites were fabricated by Si infiltration under gas flow guidance. The characteristics of these materials are significantly affected by the interfacial reaction between Si and diamond. The interface formation was studied extensively by locally analyzing the microstructure of the interfacial regions via transmission electron microscopy (TEM), field-emission scanning electron microscopy (FE-SEM), Raman spectroscopy, and X-ray diffraction (XRD). The results demonstrated that the extent of reactive erosion of diamond by Si weakened as the gas velocity increased during the infiltration process. Nanocrystalline Si 5 C 3 and β-SiC grains with an orientation relationship were observed at the diamond/SiC interface. Furthermore, by employing gas flow guidance, the diamond/SiC composites exhibited a better specific stiffness, measuring up to 183.3 × 106 m2 s−2, which represents an exceptional 18 % improvement compared with the control group. [ABSTRACT FROM AUTHOR]

To enhance the oxidation resistance of C/SiC composites, HfSiO 4 was introduced into C/SiC composites to modify the matrix utilizing two cyclic alternating preparation modes, thereby yielding the C/SiC-HfSiO 4 composites with a composite matrix. Using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), energy-dispersive spectrometer (EDS), and thermogravimetric-differential thermal analysis (TG-DTA), a comprehensive investigation was conducted into the oxidation behavior and mechanism of the prepared composites. Results reveal that the C/SiC-HfSiO 4 composites prepared using cyclic alternating preparation modes display the reduced oxidation mass loss and enhanced retention of flexural strength, despite of having higher porosity. In short, the introducing of HfSiO 4 can effectively improve the oxidation resistance of C/SiC composites. The effects of the matrix particle refinement and the synergy between the HfSiO 4 and SiO 2 jointly lead to the enhanced oxidation resistance. [ABSTRACT FROM AUTHOR]

With the rapid development of optoelectronic technology, the realization of multi-functional properties of ferroelectrics has recently become a hot research topic. In the present study, a high electrostrictive effect and excellent photoluminescence properties have been achieved by introducing rare earth Er3+ ions into the high-performance 0.96(K 0.48 Na 0.52)(Nb 0.95 Sb 0.05)O 3 -0.04Bi 0.5 (Na 0.82 K 0.18) 0.5 ZrO 3 (0.96KNNS-0.04BNKZ) ferroelectric ceramic. As a result of the Er3+ doping, the ferroelectric long-range order of 0.96KNNS-0.04BNKZ was disrupted, which led to the formation of polar nanoregions and electrostriction enhancement. The sample that was doped with 0.8 mol% Er3+ ions showed a high electrostrictive strain of ∼0.11 % (at 80 kV/cm), with a large electrostrictive coefficient, Q 33, of 0.033 m4/C2. Q 33 was not sensitive to either a temperature change or field cycling. In addition, the Er3+-modified samples showed a bright up-conversion photoluminescence with a strong green emission, which could be explained by the presence of Er3+ activator ions. Furthermore, an excellent optical temperature performance, with a sensitivity of S = 0.0075 K−1 at 570 K, was achieved for the ceramic that was doped with 0.1 mol% Er3+. This sensitivity was higher than for most rare earth-doped ferroelectric materials. Because of these excellent optical and electrical characteristics, the Er3+-doped 0.96KNNS-0.04BNKZ-based ferroelectrics demonstrated promising prospects for applications in optical-electrically integrated and coupling devices. [ABSTRACT FROM AUTHOR]

A novel MnTiNb 2 O 8 -based microwave dielectric ceramic was synthesized by solid-state route and its microwave dielectric properties were investigated. The effects of excess Mn2+ on the microstructure and microwave dielectric properties of Mn x TiNb 2 O 8 (x = 1.00–1.20) were investigated. The X-ray diffraction and scanning electron microscopy results showed that MnTiNb 2 O 8 was the dominant crystalline phase in all samples, but TiO 2 , as a second phase, was consistently present. The complex impedance spectroscopy and X-ray photoelectron spectroscopy analysis suggested that the addition of a small amount of Mn could inhibit the formation of oxygen vacancies and hinder the reduction of Ti4+. The study found that by adding a small amount of Mn, the quality factor (Q × f) of ceramics can be significantly improved without affecting the dielectric constant (ε r), thereby greatly optimizing the dielectric properties of ceramics. Subsequently, the temperature coefficient of resonant frequency (τ f) of the ceramic was successfully adjusted to near zero by adding a small amount of Zr4+ instead of Ti4+. Among all Mn x Ti 1- y Zr y Nb 2 O 8 (x = 1.00–1.20, 0 ≤ y ≤ 0.28) ceramics, samples with x = 1.05 and y = 0.1 sintered at 1200 °C showed the best microwave dielectric properties: ε r = 32.9, Q × f = 11,427 GHz, and τ f = 0 ppm/°C. [ABSTRACT FROM AUTHOR]

Near-infrared (NIR) phosphor-converted light-emitting diodes (pc-LEDs) have exhibited tremendous potential in spectroscopic technology, promoting the demand of developing novel NIR materials with excellent properties. In this paper, a series of germanate based NIR phosphors Sr 3 ZnGe 5 O 14 : xCr3+ (0 ≤ x ≤ 0.05) were synthesized by high temperature solid state reaction. The X-ray diffraction (XRD), scanning electron microscopy (SEM), Ultraviolet diffuse reflection, photoluminescence spectra and PL decay were measured to analyze the crystal structure, morphology properties and elements composition, PL emission properties and lifetimes of these NIR phosphors. Results demonstrated that phosphors Sr 3 ZnGe 5 O 14 : xCr3+ (0 ≤ x ≤ 0.05) crystallized in a trigonal with a space group of P 321(150) with a broad band gap (E g) of 4.70–4.59 eV. Sample Sr 3 ZnGe 5 O 14 : 0.03Cr3+ with the best PL emission properties showed a good thermal stability with the PL emission intensity remains 69 % of its initial value at 420 K. It's worth noting that the NIR device based on Sr 3 ZnGe 5 O 14 : 0.03Cr3+ displays an impressive electroluminescent emission stability, for example, the electroluminescent emission intensity is still about 92.3 % of its initial value when the NIR pc-LED light up for 18 h. These research results provided an important guidance for developing novel Cr3+ doped germanate based NIR phosphors with excellent thermal and electroluminescent emission stability. [ABSTRACT FROM AUTHOR]

In situ precipitation of CsPbBr 3 quantum dots (QDs) in glass is considered as one of the effective methods to overcome its instability and to achieve practical applications. However, it still faces the great challenges of low photoluminescence quantum yield (PLQY), poor thermostability and photostability at present. Herein, we successfully prepared CsPbBr 3 QDs in situ within a well-designed glass matrix (CsPbBr 3 QDs@glass), which exhibits symmetric narrowband emission at 523 nm with a full width at half maximum (FWHM) of 25 nm, giving a PLQY of up to 52.15 % under 455 nm excitation. Meanwhile, it can keep 45.25 % of the initial luminescence intensity at 373 K, better than that of most reported CsPbBr 3 QDs@glass materials. As a demonstration of a conceptual application, a white LED backlight strip was fabricated at home by encapsulating CsPbBr 3 QDs@glass composite and K 2 SiF 6 :Mn4+ red phosphor on blue chips with silicone, achieving a wide color gamut of 128.6 % and 95.8 % of NTSC and Rec. 2020 color gamut, respectively. The assembled CsPbBr 3 QDs@glass-based LCD screen exhibits excellent color reproduction and color saturation. All these results demonstrate that this CsPbBr 3 QDs@glass composite material is a promising green emitter for wide color gamut LCD display. [ABSTRACT FROM AUTHOR]

High-performance dielectric energy storage ceramics has been brought to the fore by data as a result of the rapid rise in new energy development. The dielectric energy storage materials that can withstand harsh environments while having excellent energy storage performance, large breakdown strength, and maximum polarization is highly demanding. Herein, we fabricated the BiScO 3 (BS) modified 0.88(Ba 0.6 Ca 0.4)TiO 3 -0.12Bi[Mg 2/3 (Nb 0.85 Ta 0.15) 1/3 O 3 ] (BCT-BMNT) ceramics with excellent energy storage performance. The experimental results revealed that the breakdown strength of BCT-BMNT- x BS ceramics can be substantially increased by careful engineering of the grain uniformity induced by the incorporation of the BS. The BCT-BMNT-0.2BS ceramic exhibited a considerably optimal recoverable energy storage density of 5.75 J/cm3 along with a high energy efficiency of 89.63 % at 650 kV/cm. Moreover, this sample showed good stability in the temperature range of 20–160 °C and frequency range of 1–500 Hz and excellent fatigue resistance up to 105 cycles. Regarding the pulsed performance, as-prepared sample exhibited excellent power density of 145.30 MW/cm3 and current density of 937.43 A/cm2. Meanwhile, it showed a fast discharge time (t 0.9) of 50.20 ns under the electric field of 460 kV/cm. This study demonstrates the crucial role that BS doping plays in improving the energy storage capabilities of BT-based lead-free ceramics, which pave the way for the use of BT-based ceramics in the field of energy storage. [ABSTRACT FROM AUTHOR]

Yttria-stabilized zirconia coatings were prepared by atmospheric plasma spraying, and the bonding strength of the coatings was determined by tensile testing. The microstructure of the coating, including grains and pores, was characterized using scanning electron microscopy and electron backscatter diffraction. The results show that the higher the proportion of columnar grains, the higher the bonding strength. The large misorientation at the small grains leads to large stress, which is easy to fracture in the tensile process, so the existence of small grains leads to poor bonding strength. By using image processing, pores were classified as holes, cracks, and microcracks, and their proportions were calculated. It was found that both holes and transverse and vertical cracks in pores linearly affected the bonding strength; the influence of holes was the greatest, and the influence of microcracks was the smallest. In conclusion, the smaller the porosity, the greater the bonding strength of the coating. [ABSTRACT FROM AUTHOR]

A photocurable ceramic precursor slurry with a carbon fiber content of up to 25 vol% was prepared and carbon fiber reinforced SiC ceramic matrix composites (C f /SiC composites) were successfully fabricated by stereolithography (SLA) combined with precursor infiltration and pyrolysis (PIP). The photocuring ability of the precursor composite slurry was investigated. The calculated result showed that the penetration depth of the slurry prepared with polycarbosilane (PCS) powder and chopped carbon fiber was 59.98 μm, which was suitable for stereolithography. In addition, the bulk density, porosity, flexural strength and micromorphology of the green body, debinding body and final C f /SiC composites were analyzed in detail. After eight cycles of PIP, the bulk density and flexural strength of final C f /SiC composites were 2.03 ± 0.04 g/cm3, 109.99 ± 15.05 MPa, respectively. This work provides a reference for additive manufacturing of C f /SiC composites by stereolithography. [ABSTRACT FROM AUTHOR]

Hafnon (HfSiO 4) can be applied in electronics, dielectric films, refractory materials, and many other critical application areas. To explore an efficient preparation process of HfSiO 4 , a novel non-hydrolytic sol-gel (NHSG) method was used to synthesize high-purity HfSiO 4 in this study. X-ray diffraction (XRD), field emission scanning electron microscopy (SEM), energy-dispersive spectrometer (EDS), thermogravimetric differential scanning calorimetry (TG-DSC), Fourier transform infrared spectroscopy (FT-IR), and infrared thermal imaging (ITI) were used to investigate the synthesis temperature and mechanism of HfSiO 4 and the effects of process parameters on its synthesis efficiency. The results show that the prepared sols undergo a highly reactive non-hydrolytic polycondensation reaction at room temperature. High temperature reflux or long time aging step is not necessary to form the strong Hf- O -Si bonds. Furthermore, with the introduction of the mineralizer agent LiF, the synthesis temperature of HfSiO 4 can be drastically reduced, and the HfSiO 4 with high purity can be synthesized at low temperatures. A moderate molar ratio of silicon to hafnium (Si:Hf) and molar concentration of the solution contribute to improve the synthesis efficiency of HfSiO 4 , and the purity of HfSiO 4 products can reach up to 98.12 %. [ABSTRACT FROM AUTHOR]

To improve the sliding wear resistance of plasma sprayed Mo coating, Mo–SiC and MoO 3 –Al–SiC composite powders were used to prepare Mo composite coatings by plasma spraying. The results show that the introduction of SiC improved the mechanical properties and sliding wear resistance of plasma sprayed Mo coating. The reactivity of Mo and SiC was low during plasma spraying Mo–SiC composite powder. The thermite reaction for MoO 3 and Al was not conducive to the densification of the composite coating prepared by MoO 3 –Al–SiC composite powder, but improved the reactivity of in-situ generated Mo and SiC, and the Nowotny phase Mo 4.8 Si 3 C 0.6 was observed in the coating. The coating prepared by Mo–SiC composite powder displayed better mechanical properties and sliding wear resistance than that of the coating prepared by plasma spraying MoO 3 –Al–SiC composite powder. The coating obtained by Mo–SiC composite powder revealed a combination of adhesive wear, abrasive wear and oxidation wear. [ABSTRACT FROM AUTHOR]

The continuous boron nitride (BN) fiber exhibits exceptional properties such as high-temperature resistance, excellent wave transparency, and resistance to ablation. However, ceramic BN fiber fabricated from polymer-derived ceramics (PDCs) routes often suffers from low strength, which is closely related to its orientation degree and crystallization. Utilizing stretching can improve the crystallization orientation of fiber during the heat treatment process, we present a novel approach to address this issue in this study. Graphite rings are employed to provide continuous micro-tension by restricting the shrinkage of BN fiber during the polymer-to-ceramic conversion. The micro-tension level is adjusted by the diameter variation of the graphite rings. A series of analyses reveal a significant enhancement in the orientation degree of the ceramic BN fiber, transforming it from disordered to highly oriented (with ω value of 0.84). The orientation factor (f) grows by nearly 20%. Furthermore, the crystallization increases from 81.13% to 90.72%. The ratio of pore area to cross-section area of ceramic BN fibers decline from 0.63% to 0.19%. Correspondingly, the bulk density is increased by nearly 44%. Consequently, the strength and Young's modulus of the fiber are enhanced by approximately 3 and 10 times, respectively. [ABSTRACT FROM AUTHOR]

The research and development of energy storage materials and devices has now become the current hotspot. In this work, we designed high performance (0.93- x)(Bi 0.5 Na 0.5)TiO 3 -0.07BaTiO 3 - x (Sr 0.7 Bi 0.2)TiO 3 (BNT-0.07BT- x SBT) energy storage ceramics with large recoverable energy storage density and high energy efficiency. Results showed that the introduction of SBT into BNT-0.07BT matrix improved the crystal structure symmetry of the material and induced strong relaxation behavior with broadened dielectric peak. The ferroelectric long-term order of the BNT-0.07BT matrix is destructed via SBT modification, yielding the slender P-E hysteresis loop in samples with higher SBT content. Good energy storage performance with large effective energy storage density W rec of 3.26 J/cm3 and high energy storage efficiency η of 90.3% was obtained in 40 mol%SBT -modified sample, under the electric field of 260 kV/cm. The charge-discharge performance test showed that the sample exhibited a short discharge time (t 0.9 = 143 ns) and a relatively high power density (P D = 40.8 MW/cm3) under an electric field of 160 kV/cm. Moreover, sample showed good thermal stability in the temperature range of 30–180 °C and high frequency stability in the frequency range of 1–1000 Hz. As an attractive material for dielectric capacitor, BNT-0.07BT- x SBT energy storage ceramics have potential applications in pulse power systems. [ABSTRACT FROM AUTHOR]

High performance absorbing coatings attract great interest because of the urgent demand for radar stealth technology. However, most reported absorbing coatings focused on the incident microwave were perpendicular to the surface of the coatings. Here, a kind of absorber of TiC/Al 2 O 3 was prepared by plasma spraying method and the influence of TiC content and oblique incident microwave irradiation on the absorbing properties of TiC/Al 2 O 3 were reported. The absorbing performance firstly increased and then decreased with increasing the TiC content due to the impedance matching and attenuation constant cannot match well at the same time. Meanwhile, compared with TE polarization, TM polarization of the plasma-sprayed TiC/Al 2 O 3 coatings was more sensitive to the incident angle. This study demonstrates the feasibility of plasma-sprayed TiC/Al 2 O 3 absorbing coatings for electromagnetic applications. [ABSTRACT FROM AUTHOR]

Dense SiC-(Ti x Zr 1–x)B 2 composite ceramics were prepared via solid-state spark plasma sintering (SPS) by controlling the proportion of ZrB 2 (in the range of 5–25 vol%). Through data fitting, a linear functional relationship was established between x and 2θ for the (Ti x Zr 1–x)B 2 solid solution, which rendered it amenable to characterization analysis. The results show that the 2-D morphology of (Ti x Zr 1–x)B 2 tended to transform from angular to round as the ZrB 2 proportion was increased, which was beneficial in crack deflection and increasing the fracture toughness. Moreover, the growth of SiC grains around the solid solution was inhibited, which improved its mechanical properties. The composite ceramic containing 15 vol% of ZrB 2 had the best mechanical properties, with its Vickers hardness, bending strength and fracture toughness reaching 26.12 GPa, 499 MPa, and 6.45 MPa•m1/2, respectively. [ABSTRACT FROM AUTHOR]

Amorphous boron nitride (aBN) materials have similar density to crystalline phases and retain many unique electronic properties, valuable chemical inertness and high thermal stability characteristics. However, the current research on aBN materials has mainly focused on the synthesis and electrical properties of ultrathin aBN films. In this study, we developed a post-annealing assisted femtosecond laser deposition route towards stoichiometric, continuous, and multifunctional aBN films with thickness values of ∼1 μm. A series of boron nitride films were deposited on silicon wafers using a 1030 nm, 300 fs laser with a pulse energy of ∼1 mJ and a high repetition rate of 2 kHz to ablate a hexagonal boron nitride target. The deposited films were then annealed at 900 °C in a nitrogen atmosphere. The structures and chemical compositions of these obtained films were analysed by X-ray diffraction and X-ray photoelectron spectroscopy. Fourier transform infrared and nano-scratch tests were performed to measure the infrared optical and frictional properties of the adhered films. An infrared thermal imager was used to investigate the heat-dissipation performance of these films. The results indicate the components of the aBN film are further purified, the number of large heterogeneous particles is effectively reduced, and the surface becomes smooth after post-annealing treatment. This improvement promotes the transfer of heat flux and increases the transmittance in the mid-infrared light band. The significant effect mechanisms of the post-annealing treatment on the enhancement of the composition and multifunctional properties of aBN films prepared by the femtosecond pulsed laser were provided. The uniform coverage of the aBN films on the substrates, as well as the mid-infrared optical transparency and the protective performance are highly valuable and practical for infrared window protection applications. [ABSTRACT FROM AUTHOR]

With the development of modern science and technology, the coatings with the single function of anti-corrosion have failed to cover the special requirements in various practical applications. Particularly, the good heat dissipation effect of anti-corrosive coatings is highly demanded in some devices like electrical machinery, heat exchanger and printed circuit board. Here, a facile, eco-friendly, low-cost method is developed to fabricate thermally conductive and anti-corrosive composite coatings by mixing fillers (including boron nitride (BN) and graphene nanoplatelet (GNP)), polyvinyl pyrrolidone (PVP) and waterborne epoxy resin (WER). The hybridization of BN and GNP is used to provide more barriers to delay the penetration of corrosive medium and construct a denser heat conduction network in the composite coatings. PVP is selected as the compatibilizer to further improve the anti-corrosion and thermal conductivity of composite coatings. The effects of filler types and contents on the anti-corrosive and thermally conductive properties are researched. At the loading of 30 wt% BN and 0.5 wt% GNP, the BN@GNP/PVP/WER coating reaches the optimizing anti-corrosive ability, where the |Z| value holds around 6.5 × 109 Ω cm2 after soaking in the corrosive medium for 7 days, and the I corr and E corr values are 1.9 × 10−9 A/cm2 and -0.62742 V, respectively. Meanwhile, this coating displays great heat conduction with the thermal conductivity of 0.87 W/mK at about 30 wt% filler loading. Moreover, the electrical properties and hydrophilicity of coatings at different filler formulations are studied. It is worth noting that the higher electrical conductivity of the coatings at higher GNP content may accelerate the corrosion rate. This study provides a simple route for the design and manufacture of highly anti-corrosive and heat-conducting composite coatings, which exhibits great potential application in next-generation electronic packaging and devices. [ABSTRACT FROM AUTHOR]

The weak interface is a key issue that needs to be addressed for the carbon nanotubes (CNTs) reinforced metal matrix composites. Herein, uniform and continuous Cr(OH) 3 coating was firstly decorated on the surface of CNTs, and Cr(OH) 3 coating was subsequently thermally decomposed into the Cr 2 O 3 transition layer during the fabrication processes for the Cu matrix composite. It is found that the precoating Cr(OH) 3 on CNTs can promote the dispersion of CNTs in the Cu matrix because the coating can reduce the density difference between CNTs and Cu powders. Meanwhile, the Cr 2 O 3 transition layer has obvious constituent interaction with the Cu matrix, and in-situ nanosized Cr carbides (Cr 2 C 3 and Cr 23 C 6) form between the CNTs and Cr 2 O 3 layer, forming a composite interface structure. Benefiting from the homogeneous dispersion of the decorated CNTs and enhanced interfacial bonding, the compression yield strength of the bulk composite reaches 383.5±21.0 MPa, showing a 217% and 147% increase over the pure Cu and the composite reinforced by uncoated CNTs, respectively. The substantially enhanced strength mainly derives from the strengthening mechanisms of Orowan looping and load transfer. The developed novel strategy paves a new route for interface regulation and strength improvement of other CNTs reinforced metal matrix composites. [ABSTRACT FROM AUTHOR]

Fabrication of flexible photocatalysts with the heterostructure is one of promising approaches to improve the photocatalytic activity and reusability. In the present work, the In 2 O 3 /In 2 S 3 heterostructures were synthesized by the solvothermal reactions. And the In 2 O 3 /In 2 S 3 @PAN nanofibers were synthesized by loading In 2 O 3 /In 2 S 3 nanoparticles on the surface of PAN nanofibers. The SEM, TEM and elemental mapping images exhibit the homogeneous distribution of the In 2 O 3 /In 2 S 3 nanoparticles over the whole surface of nanofibers. The increased photocurrent density and decreased radius of EIS curve indicate that higher effective separation for photogenerated electron-hole pairs and charge transfer were obtained by the In 2 O 3 /In 2 S 3 heterostructures. The loading on the surface of PAN nanofibers gives a larger number of photoactive sites to the H 2 evolution reactions. And the H 2 evolution rate in the photocatalytic process with the presence of the In 2 O 3 /In 2 S 3 -3@PAN photocatalyst is ∼10.32 and ∼5.33 times higher than the rates of pure In 2 O 3 and In 2 S 3. [ABSTRACT FROM AUTHOR]

(1- x) (0.935BNT–0.065BaTiO 3)- x SrRECoO 4 (BNBT6.5- x SREC, RE = Pr, Eu, Sm)–based lead-free ferroelectric ceramics with large electrostrain and photoluminescence effect were prepared in our work. Through introducing the SREC dopant into BNBT6.5, the long-range ferroelectric order of ceramics was disrupted, inducing a weak polar state dominated by polar nanoregions before applying an electric field. Due to the reversible transition of PNRs under the electric field, the electrostrain was greatly promoted. When the content of SREC was 0.012, large field-induced large strains of 0.38–0.44% were obtained under an electric field of 70 kV/cm, equivalent to a large signal d 33 * (S max / E max) of 543–586 pm/V. Moreover, relying on the luminescence effect of RE3+ ions in SREC, the modified ceramics exhibited strong photoluminescence with bright red or orange emissions, depending on the type of RE elements. However, the strong emission was strongly quenched in samples with a higher SREC content due to the photoluminescence quenching effect of the heavy metal (Co3+) ions in the SREC dopant. The quenching model can be based on the formation of non-radiative recombination centers induced by Co3+ ions, which affect the energy transition of RE3+ ions from the excited state to the ground state. [ABSTRACT FROM AUTHOR]

The effect of Zr4+ substitution for Ti4+ on the phase evolution and microwave dielectric properties of (Cu 1/3 Nb 2/3) 0.25 Ti 0.75- x Zr x O 2 (0 = x ≤ 0.35) ceramics prepared via conventional solid-state method has been investigated. With the increase of Zr substitution, the ceramics exhibit a gradual phase transition from a tetragonal rutile phase to an orthorhombic srilankite phase, where the synthesis of the srilankite phase at atmospheric pressure and temperature below 1200 °C in this study is reported for the first time. The crystal structure is tetragonal rutile type for the unsubstituted composition, orthorhombic srilankite type for the compositions with x > 0.30, and the compositions in between is a two-phase region with a mixture of rutile and srilankite. The Zr substitution has a great influence on the microstructure of the ceramics. In particular, for compositions where x > 0.1, the grain boundaries are surrounded by elongated powdery particles. The microwave dielectric properties of the ceramics are closely related to the phase transition process, in which Q × f is significantly improved and τ f decreases almost linearly with the increase of the content of srilankite phase. Optimum microwave dielectric properties with a permittivity of 35.1, a Q × f value of 7270 GHz, and a near-zero τ f of 9.0 ppm/°C are obtained in the ceramics with x = 0.3 sintered at 1150 °C for 4 h, which provides a new option for microwave devices requiring medium-permittivity dielectric ceramics. [ABSTRACT FROM AUTHOR]

The development of high-performance thermally conductive fillers is crucial for the thermal management of polymer-based composites. Herein, a facile precursor pyrolysis strategy was adopted to fabricate boron nitride@multiwalled carbon nanotubes (BN@MWCNTs) fillers, wherein uniformly distributed MWCNTs were firmly anchored on BN microrods. Benefiting from the unique structure, the BN@MWCNTs act as fillers in the design of polystyrene (PS)/BN@MWCNTs composites via in situ polymerization. As a result, a 7.74-fold higher thermal conductivity (TC) (9.55 W/m·K) was achieved for the 10 wt% BN@MWCNTs, as compared to native PS/BN/MWCNTs prepared by the conventional melt-mixing method. More importantly, the PS/BN@MWCNTs composites exhibited satisfactory electrical insulation owing to the isolation effect of BN. Overall, this work provides a promising frontier for the design of polymer-based thermally conducting materials for applications in thermal management. [ABSTRACT FROM AUTHOR]

A series of La (3- x) Dy x BWO 9 phosphors and La (3- x) Dy x BWO 9 /PMMA composite films were prepared. The absorption and photoluminescence of phosphors as well as the transmittance and radioluminescence of the composite films were studied. La (3- x) Dy x BWO 9 phosphors mainly emit blue light at 486 nm and yellow light at 577 nm when excited at 310 nm, and the phosphors have good thermal stability. La (3- x) Dy x BWO 9 /PMMA composite films have good transmittance and X-ray radiation properties. The results indicate that La (3- x) Dy x BWO 9 phosphors can be used in solid-state lighting devices, and the prepared composite films are expected to be used in fields such as X-ray imaging and radiation detection. [ABSTRACT FROM AUTHOR]

The solvent-based resins have been applied widely in the preparation of thermal interface material (TIM). However, the use of solvents is harmful to the environment and human health. To address this, an environment-friendly TIM is fabricated by employing waterborne epoxy as a polymer matrix in this research project. The waterborne epoxy resin/polyvinyl pyrrolidone/hexagonal boron nitride (WER/PVP/h-BN) composite is successfully prepared through a facile method. First, the WER/PVP/h-BN mixture is obtained by a one-pot process. Subsequently, the WER/PVP/h-BN composite is fabricated by heat curing. The thermal conductivity of obtained WER/PVP/h-BN composite can reach 1.0921 W/m·K at 40 wt% filler loading. The mechanism of PVP for thermal conductivity enhancement of composites is demonstrated utilizing effective medium theory (EMT) and Fogyel's models. Furthermore, the mechanical, electrical, and surface properties of WER/PVP/h-BN composites are comprehensively investigated. The valuable information and insight for the design and preparation of environment-friendly TIMs are provided in this paper. [ABSTRACT FROM AUTHOR]

YCr 0.5 Mn 0.5 O 3 (YCM)-CaCu 3 Ti 4 O 12 (CCTO) ceramics were prepared using a solid processing method, and their properties were studied. XRD measurements showed that all prepared ceramics had pure perovskite structures. With increasing YCM content, grain size in ceramics decreased, and the resistivity of materials was found to be very sensitive to grain size and grain size distribution. Moreover, ceramics had NTC characteristics, and values of ρ 25 , B 25/75 , and E a ranged from 2.21 × 106–7.30 × 106 Ω cm, 5797–6300 K, and 0.5390–0.5800 eV, respectively. The presence of heterovalent ion pairs in samples suggested that conduction mechanism may have been related to electron hopping. Impedance spectroscopy results showed that excessive doping with YCM resulted in greater contribution from grains to overall resistance of the material. Temperature-dependent electrical relaxation behavior was dominated by short-range movement of charge carriers. [ABSTRACT FROM AUTHOR]

Dielectric capacitors show great potential in superior energy storage devices. However, the energy density of these capacitors is still inadequate to meet the requirement of energy storage applications. In this study, the Bi 0.5 Na 0.47 Li 0.03 TiO 3 - x NaNbO 3 (BNLT- x NN) ceramics were prepared via conventional solid-phase reaction. Results showed that NN can efficaciously enhance the breakdown strength (E b) and the relaxation behavior of the BNLT ceramic because of the broken ferroelectric long-range order. When x = 0.3, the maximum E b reached 350 kV/cm, at which the 0.7BNLT-0.3NN ceramic exhibited the high recoverable energy storage density (W rec) of 4.83 J/cm3 and great efficiency (η) of 78.9%. The ceramic demonstrated good temperature stability at 20 °C-160 °C and excellent fatigue resistance. Additionally, the 0.7BNLT-0.3NN ceramic presented high power density (P D ; ∼77.58 MW/cm3), large current density (C D ; ∼861.99 A/cm2), and quite short discharge time (t 0.9 ; ∼0.090 μs). These results indicated that the 0.7BNLT-0.3NN material has excellent energy storage properties and various application prospects. [ABSTRACT FROM AUTHOR]