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Low-temperature, low-pressure Cu-to-Cu direct bonding technology is a promising solution for next-generation high-density interconnects. Previous studies have shown that many properties of nanomaterials are determined by their structural characteristics. Therefore, the effect of the nanostructure (i.e., twin crystal and twin boundary, TB, sizes) on the bonding mechanism and mechanical response of the direct bonding of (111)-oriented nanotwinned Cu (NT-Cu) is studied using molecular dynamics simulations, where TB size means the TB layer thickness in terms of the number of atoms. The simulation results show that NT-Cu with extremely small twin crystals (e.g., 0.625 nm) have poor diffusivity. The number of dislocations induced by plastic deformation increases with increasing twin crystal size during stretching processes, degrading mechanical strength. The strain hardening of bonded NT-Cu with extremely small twin crystals (e.g., 0.625 nm) is dominated by the strong barrier created by a high density of TBs, whereas that with twin crystal sizes of 2.5–10 nm is dominated by dislocation–TB and dislocation–grain boundary interactions. Bonded NT-Cu with 2–6 atoms per TB layer exhibits softening at initial plastic deformation due to the onset of partial collapse of TBs; however, the strength then significantly increases with a further increase in strain due to strain hardening. [ABSTRACT FROM AUTHOR]

Filler morphology control is critical for enhancing the gas separation performance of mixed matrix membranes (MMMs). A vertical transport channel using the crystal twinning phenomenon is designed on the zeolitic imidazolate framework (ZIF) nanoplate. Twinned ZIF‐8 (TZIF‐8) nanoplate is prepared by controlling the shape of ZIF‐L from nanosheet to twinned flake, followed by conversion into the ZIF‐8 phase. With the addition of TZIF‐8 in 6FDA‐DAM polymer, propylene/propane selectivity is dramatically enhanced, showing propylene permeability of 40 Barrer and propylene/propane selectivity of 82. The separation performance surpasses the performance of MMMs reported so far, and the selectivity is comparable to that of polycrystalline ZIF‐8 membranes. A transport mechanism study using mathematical models implies that the percolated twin fillers create rapid and selective gas channels for desired molecules and substantial tortuous pathways for undesired molecules. [ABSTRACT FROM AUTHOR]

Crystals of 1-nitronaphthalene were grown by evaporation of a methanol solution. The structure [P21/c, a = 13.2780(13) Å, b = 3.8131(3)° Å, c = 31.851(3) Å, β = 91.173(8), V = 1,612.3 Å3] was solved from a crystal twinned by twofold rotation about [100]. Twinning is explained by the polytype character: layers with (idealized) p2111 symmetry can connect via either 1‾ or 21 operations, leading to geometrically distinct pairs of layers. In the twin individuals, the two kinds of contacts alternate, at the composition plane two subsequent contacts of the same type are realized. [ABSTRACT FROM AUTHOR]

Electron backscattered diffraction (EBSD) characterization was conducted on the typical regions in friction-stir-welded dissimilar Al/Mg joints of 2 mm thick sheets with/without ultrasonic assistance. The effects of ultrasonic vibration (UV) on the grain size, recrystallization mechanisms, and degree of recrystallization on both sides of the Al-Mg bonding interface and the intermetallic compounds (IMCs) were investigated. It was found that on the Mg side of the weld nugget zone (WNZ), the primary dynamic recrystallization (DRX) mechanisms were discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX), with geometric dynamic recrystallization (GDRX) playing a secondary role. On the Al side of the WNZ, CDRX was identified as the primary mechanism, with GDRX as a secondary contributor. While UV did not significantly alter the DRX mechanisms in either alloy within the WNZ, it promoted the aggregation and rearrangement of dislocations. This led to an increase in high-angle grain boundaries (HAGBs) and an enhanced degree of recrystallization in the welds. The average grain size in both the Al and Mg alloys of the WNZ followed a pattern of initially increasing and then decreasing along the thickness direction, reaching a maximum in the upper-middle part and a minimum at the bottom. The influence of UV on the average grain size in the WNZ was minimal, with only slight grain refinement observed, and the minimum refinement degree was only 0.9%. The Schmid factor (SF) on the WNZ and thermo-mechanically affected zone (TMAZ) boundary regions of the advancing side (AS) indicates that the application of UV increased the likelihood of basal slip and extension twinning in the crystal structure. In addition, UV reduced the thickness of IMCs and improved the strength of the Al-Mg bonding interface. These results suggest a higher probability of fracture along the TMAZ and WNZ boundary on the AS when UV was applied. [ABSTRACT FROM AUTHOR]

A domain‐resolved synchrotron single‐crystal X‐ray diffraction study of a LaAlO3 pseudo‐merohedral twin crystal was successfully carried out in combination with powder diffraction data from the same sample. Multiscale structure information ranging from micro‐ to nano‐ to atomic scale was determined from one single crystal. There is almost no change of domain ratios at temperatures of less than 400 K indicating no movement of the domain wall. The changes in domain ratio indicating domain‐wall movement were observed in the temperature range of 450 to 700 K, which is consistent with the result of the previous mechanical measurement. It is also found that the ratio of four twin components becomes equal (25%), just below phase transition temperature. These findings are important for domain engineering and theoretical studies related to LaAlO3. The temperature dependence of domain ratio was preserved in the heating and cooling cycle except for the first heating process to 840 K. Therefore, the domain structure after heating to 840 K is intrinsic to the crystal. Accurate structure parameters were determined through unit‐cell parameter calibration and domain‐resolved structure analysis. The method for calibration of unit‐cell parameters from twin crystal data was derived and used to solve the inconsistent unit‐cell parameters between single crystal and powder data in the present and previous studies. [ABSTRACT FROM AUTHOR]

In photocatalysis, maximizing light absorption and utilizing light-stimulated electrons is of paramount importance. In this study, Ni-decorated Cd x Zn 1−x S twinned crystals were synthesized via solvothermal method with Ni loadings ranging from 0.5 to 5 wt%. The Ni nanoparticles introduced the Surface Plasmon Resonance (SPR) effect, broadening photon absorption and extending the photo-response into the visible light range. Notably, 1 wt % Ni-decorated Cd 0.5 Zn 0.5 S exhibited remarkable H 2 evolution rate of 1497 μmol(h.g cat)−1. This enhancement is attributed to the SPR effect, which enhances light absorption and photogenerated electron generation, as well as efficient electron transfer facilitated by Ni's lower Fermi level. These findings emphasize the crucial role of optimal Ni loading and the SPR effect in enhancing photocatalytic efficiency. [Display omitted] • The Ni–Cd 0.5 Zn 0.5 S absorbs visible light more efficiently due to the SPR effect. • Amplified electric field in Ni-decorated Cd x Zn 1−x S broadens the photoresponse. • Optimal Ni loading is key to enhancing photocatalytic efficiency. • Optimized reactivity achieved via surface and defect engineering synergy. [ABSTRACT FROM AUTHOR]

The article discusses the author's experience as a mineral collector and the joy they found in sharing their collection with others. The author contrasts their collection, which was not behind glass and could be handled and examined closely, with private collections that are encased behind glass and are untouchable. The author also describes the challenges of collecting small single crystals and twinned crystals and shares their own methods of storing and displaying their collection. The article concludes by expressing the author's joy in collecting and sharing their collection, while also acknowledging the limited availability and affordability of certain types of crystals. [Extracted from the article]

Chlorine ions play an important role in the corrosion of bronzeware. This study employs techniques such as XRD, OM, SEM, EBSD, and electrochemical testing to analyze the microstructure, crystal structure, chemical composition, and corrosion performance of bronze earrings unearthed at the Xindianzi site in Inner Mongolia. The results indicate the presence of work-hardened structures, including twinning and equiaxed crystals, on the earrings' surface. With an increase in chloride ion concentration in NaCl solutions from 10−3 mol/L to 1 mol/L, the corrosion current density of the bronze earrings increased from 2.372 × 10−7 A/cm2 to 9.051 × 10−7 A/cm2, demonstrating that the alloy's corrosion rate escalates with chloride ion concentration. A 3-day immersion test in 0.5% NaCl solution showed the formation of a passivation layer of metal oxides on the earrings' surface. These findings underscore the significance of the impact chloride ions have on the corrosion of copper alloys, suggesting that activating the alloy's reactive responses can accelerate the corrosion process and provide essential insights into the corrosion mechanisms of bronze artifacts in chloride-containing environments. [ABSTRACT FROM AUTHOR]

At room temperature, the title salt, C7H10NO+.Cl-, is orthorhombic, space group Pbca with Z' = 1, as previously reported [Zhao (2009). Acta Cryst. E65, o2378]. Between 250 and 200 K, there is a solid-state phase transition to a twinned monoclinic P21/c structure with Z' = 2. We report the high temperature structure at 250 K and the low-temperature structure at 100 K. In the low-temperature structure, the -NH3 hydrogen atoms are ordered and this group has a different orientation in each independent molecule, in keeping with optimizing N--H. . .Cl hydrogen bonding, some of which are bifurcated: these hydrogen bonds have N. . .Cl distances in the range 3.1201 (8)-3.4047 (8) A. In the single cation of the high-temperature structure, the NH hydrogen atoms are disordered into the average of the two low-temperature positions and the N. . .Cl hydrogen bond distances are in the range 3.1570 (15)-3.3323 (18) A. At both temperatures, the methoxy group is nearly coplanar with the rest of the molecule, with the C--C--O -- C torsion angles being -- 7.0(2)° at 250 K and --6.94 (12) and -- 9.35 (12)° at 100 K. In the extended orthorhombic structure, (001) hydrogen-bonded sheets occur; in the monoclinic structure, the sheets propagate in the (010) plane. [ABSTRACT FROM AUTHOR]

A mixed metal oxide, ZnMoO 4 has been prepared by the conventional solid-state reaction method, with the help of hydrothermally synthesized solvents of ZnO and MoO 3. The phase purity and surface morphology of the precursors of ZnO and MoO 3 are resolved with the Rietveld refinement and scanning electronic microscopy studies. Structural, morphological, and vibrational modes characterizations associated with the unit cell information of ZnMoO 4 are explained by Rietveld's refined technique of XRD, SEM, and Raman studies, respectively. The anode solvent ZnMoO 4 is subjected to cyclic voltammetry analysis. Hence, the electrochemical impedance spectroscopy (EIS) measurements are recorded between 3.0 and 0.01 V at a scan rate of 0.5 mV s−1 for ZnMoO 4 electrodes as an anode material in LIBs. Here, it has been noticed that the hexagonal-like ZnMoO 4 has high capacity and reasonable cycle stability compared with ordinary ZnMoO 4. An anomalous change in permittivity and tangent loss at T θ =750K in temperature dependent dielectric studies confirm phase transition due to the transformation of molecular groups, MoO 4 (low temperature) triclinic phase into molecular groups, MoO 6 (high temperature) monoclinic phase. The temperature and frequency dependent AC-conductivity at different intervals reveal mechanisms associated with different temperature regions. This study provides an in-depth understanding of the electrical and electrochemical activities of zinc molybdate anode materials in novel applications. [ABSTRACT FROM AUTHOR]

The mol­ecular and crystal structure of a discrete [Ni8(μ4-OH)6(μ-4-Rpz)12]2− (R = H; pz = pyrazolate anion, C3H3N2−) cluster with an unprecedented, perfectly cubic arrangement of its eight Ni centers is reported, along with its lower-symmetry alkyl-functionalized (R = methyl and n-oct­yl) derivatives. Crystals of the latter two were obtained with two identical counter-ions (Bu4N+), whereas the crystal of the complex with the parent pyrazole ligand has one Me4N+ and one Bu4N+ counter-ion. The methyl derivative incorporates 1,2-di­chloro­ethane solvent mol­ecules in its crystal structure, whereas the other two are solvent-free. The compounds are tetra­butyl­aza­nium tetra­methyl­aza­nium hexa-μ4-hydroxido-dodeca-μ2-pyrazolato-hexa­hedro-octa­nickel, (C16H36N)(C4H12N)[Ni8(C3H3N2)12(OH)6] or (Bu4N)(Me4N)[Ni8(μ4-OH)6(μ-pz)12] (1), bis­(tetra­butyl­aza­nium) hexa-μ4-hydroxido-dodeca-μ2-(4-methyl­pyrazolato)-hexa­hedro-octa­nickel 1,2-di­chloro­ethane 7.196-solvate, (C16H36N)2[Ni8(C4H5N2)12(OH)6]·7.196C2H4Cl2 or (Bu4N)2[Ni8(μ4-OH)6(μ-4-Mepz)12]·7.196(ClCH2CH2Cl) (2), and bis­(tetra­butyl­aza­nium) hexa-μ4-hydroxido-dodeca-μ2-(4-octylpyrazolato)-hexa­hedro-octa­nickel, (C16H36N)2[Ni8(C11H19N2)12(OH)6] or (Bu4N)2[Ni8(μ4-OH)6(μ-4-nOctpz)12] (3). All counter-ions are disordered (with the exception of one Bu4N+ in 3). Some of the octyl chains of 3 (the crystal is twinned by non-merohedry) are also disordered. Various structural features are discussed and contrasted with those of other known [Ni8(μ4-OH)6(μ-4-Rpz)12]2− complexes, including extended three-dimensional metal–organic frameworks. In all three structures, the Ni8 units are lined up in columns. [ABSTRACT FROM AUTHOR]

Nickel nanostructures on the surface of Si (111) 7 × 7 at different deposition intervals were obtained by thermal deposition under ultrahigh vacuum conditions without cooling the sample and injecting inert gases into the volume. It is shown that at the initial stage of deposition within 1 s, nickel forms structures of the "ring-cluster" type Ni-Si with a height of about 0.11 nm and a structural type of 1 × 1. With increasing deposition time, the formation of a thin film by the Volmer–Weber mechanism was observed. Thermal loading on Ni-Si quantum dots 1 × 1 at 980 °C leads to the formation of NiSi2 clusters with a characteristic spread in size of ~ 1.0 nm and their localization area along the twinning boundary of the crystal. Ni-Si quantum dots show resonant tunneling through discrete levels. [ABSTRACT FROM AUTHOR]

Research works on phase change random access memory (PCRAM) based on Ge–Sb–Te (GST) phase change materials have achieved exciting progress, but the industrialization of PCRAM still faces big challenges, including unsatisfied endurance property or unexpected cell structure failure during fabrication. Here, we investigate the impact of the thermal budget in back-end-of-line (BEOL) process on the microstructure evolution of carbon doped GST (CGST) cells. We demonstrate that the as-deposited amorphous CGST in the confined memory cell will transform to face centered-cubic (FCC) phase with uniform grain size during high temperature up to 400 °C in the BEOL process. However, if there is much more unexpected thermal budget during the BEOL process, the FCC-CGST grains will further grow and transform to highly ⟨0001⟩ oriented single crystalline hexagonal (HEX) GST, together with the formation of voids, leading to the structure failure of the storage cells. By virtue of the advanced spherical aberration corrected transmission electron microscopy (Cs-TEM), we find that there are randomly stacked seven-layered and nine-layered atomic arrangements in single crystalline HEX-GST, corresponding to the chemical stoichiometry of Ge2Sb2Te5 and Ge1Sb2Te4, respectively. Interestingly, twin crystal with the coexistence of vacancy-ordered FCC-GST and HEX-GST on the different twin boundary is observed, indicating that the twin crystals play a critical role in the coalescence and the growth of FCC-GST. This work not only sheds light on the structure failure mechanism of GST cell but also provided additional insight into the formation of HEX-phase in a confined GST memory cell. [ABSTRACT FROM AUTHOR]

An impact test was conducted on a single crystal of an Fe–3mass%Al alloy with a bcc structure. Microstructural changes in the sheared regions resulting from the impact test were examined. Deformation twinning was observed, with the twinning plane K 1 = { 332 } and the twinning shear direction η 1 = ⟨ 11 3 ¯ ⟩. The conjugate twinning direction η 2 of this mode was discussed. Considering the shear direction required to induce deformation twinning, it can be concluded that η 2 = ⟨ 110 ⟩ is appropriate for the twinning mode in the Fe–3mass%Al. [ABSTRACT FROM AUTHOR]

The concept of apparent symmetry rising, opposite to symmetry breaking, was proposed to illustrate the unusual phenomenon that the symmetry of the apparent morphology of the multiply twinned particle is higher than that of its crystal structure. We developed a unique strategy of co-crystallization-driven self-assembly of amphiphilic block copolymers PEO-b-PS and the inorganic cluster silicotungstic acid to achieve apparent symmetry rising of nanoparticles under mild conditions. The triangular nanoplates triply twinned by orthogonal crystals (low symmetry) have an additional triple symmetry (high symmetry). The appropriate crystallization inhibition of short solvophilic segments of the block copolymers favors the oriented attachment of homogeneous domains of hybrid nanoribbons, and consequently forms kinetic-controlled triangular nanoplates with twin grain boundaries. The concept of apparent symmetry rising, opposite to symmetry breaking, was proposed to illustrate the unusual phenomenon that the symmetry of the apparent morphology of the multiply twinned particle is higher than that of its crystal structure. Here the authors develop a strategy of co-crystallization-driven self-assembly of amphiphilic block copolymers and the inorganic clusters to achieve apparent symmetry rising of nanoparticles under mild conditions [ABSTRACT FROM AUTHOR]

The concerted experimental and computational study reports on the polymorphic behavior of RuBr3. Highly‐resolved X‐ray powder diffraction measurements of the modification lt‐RuBr3 give direct evidence for peak splitting substantiating an orthorhombic unit cell with additional weak intensities confirming a primitive lattice. The crystal structure of lt‐RuBr3 is determined using the intensities of a "Drilling" individuum. For lt‐RuBr3, findings of density functional theory calculations suggest that the deviation from hexagonal symmetry is mainly driven by electronic correlations. Reinvestigation of the recently reported high‐pressure modification hp‐RuBr3 essentially confirms the rhombohedral BiI3‐type crystal structure (space group R3‾ ${\bar{3}}$). Simulations of the atomic arrangement of hp‐RuBr3 indicate that spin‐orbit coupling and corrections for the van‐der‐Waals dispersive forces are mandatory to reach a reasonable agreement with the experimentally determined crystal structure. [ABSTRACT FROM AUTHOR]

The concerted experimental and computational study reports on the polymorphic behavior of RuBr3. Highly‐resolved X‐ray powder diffraction measurements of the modification lt‐RuBr3 give direct evidence for peak splitting substantiating an orthorhombic unit cell with additional weak intensities confirming a primitive lattice. The crystal structure of lt‐RuBr3 is determined using the intensities of a "Drilling" individuum. For lt‐RuBr3, findings of density functional theory calculations suggest that the deviation from hexagonal symmetry is mainly driven by electronic correlations. Reinvestigation of the recently reported high‐pressure modification hp‐RuBr3 essentially confirms the rhombohedral BiI3‐type crystal structure (space group R3‾ ${\bar{3}}$). Simulations of the atomic arrangement of hp‐RuBr3 indicate that spin‐orbit coupling and corrections for the van‐der‐Waals dispersive forces are mandatory to reach a reasonable agreement with the experimentally determined crystal structure. [ABSTRACT FROM AUTHOR]

In this work, single-crystal and twin-crystal copper sulfide materials are constructed in a regulatable and controlled manner. Twin boundaries are engineered into the copper sulphide material to significantly improve its electrochemical performance. The results demonstrate that structure tuning with twin crystals is an effective strategy for enhancing electrochemical reactions, and also sheds light on the design of electrode materials for sodium ion storage. [ABSTRACT FROM AUTHOR]

Pyrite and marcasite aggregates were found in a sample of blue silty clay from an exploration drill core at the northern edge of the Troyanovo North mine, Maritsa East lignite basin, Bulgaria. The aggregates have various sizes -- from 50 µm (single crystal twins) to 0.5 cm (large twinned aggregates). Pyrite occurs as single cubic and cuboctahedral crystals, penetrative twins forming oval-shaped aggregates with visible cubic to truncated octahedral habits. Marcasite occurs as single tabular, pyramidal crystals, but often as twinned (penetrative, parallel, contact) composite oval-shaped aggregates. Marcasite has higher trace element contents than pyrite. In both minerals are detected Mn, Co, Ni, Cu, Zn, Mo, As, Sb, Hg, Tl and Pb with varying contents. The crystal aggregate growth is slow in varied supersaturation and pH due to the occurrence of both octahedral and cubic faces in pyrite and marcasite presence. [ABSTRACT FROM AUTHOR]

Two thin film deposition routes were studied for the growth of high quality single crystalline Ru (0001) epitaxial films on c-Al2O3 substrates using radio frequency-magnetron sputtering. Such films are very important as buffer layers for the deposition of epitaxial non-collinear antiferromagnetic Mn3X films. The first route involved depositing Ru at 700 °C, leading to a smooth 30 nm thick film. Although, high resolution x-ray diffraction revealed twinned Ru film orientations, in situ post-annealing eliminated one orientation, leaving the film orientation aligned with the substrate, with no in-plane lattice rotation and a large lattice mismatch (13.6%). The second route involved the deposition of Ru at room temperature followed by in situ post-annealing at 700 °C. Transmission electron microscopy confirmed a very high quality of these films, free of crystal twinning, and a 30° in-plane lattice rotation relative to the substrate, resulting in a small in-plane lattice mismatch of –1.6%. X-ray reflectivity demonstrated smooth surfaces for films down to 7 nm thickness. 30 nm thick high quality single-crystalline Mn3Ga and Mn3Sn films were grown on top of the Ru buffer deposited using the second route as a first step to realize Mn3X films for antiferromagnetic spintronics applications. [ABSTRACT FROM AUTHOR]

The suitability of diethylgallium ethoxide (Et2GaOEt) containing Ga–O bonds as a Ga precursor for beta-gallium oxide (β-Ga2O3) growth by metalorganic vapor phase epitaxy (MOVPE) was investigated. Because estimating the growth behavior by thermodynamic analysis is difficult as a result of a lack of knowledge about the thermodynamics of Et2GaOEt, the growth behavior was estimated by observing its pyrolysis and combustion processes. Mass spectrometric analysis of gases sampled directly from an MOVPE reactor when only Et2GaOEt was supplied revealed that Et2GaOEt was decomposed to gallane, ethylene, and acetaldehyde by β-hydrogen (β-H) elimination at temperatures greater than 450 °C. However, when Et2GaOEt was supplied together with O2 to the MOVPE reactor maintained at 1000 °C, the combustion of hydrogen and carbon derived from Et2GaOEt was accelerated as the O2 supply was increased. In addition, the amount of O2 required for the complete combustion of Et2GaOEt (i.e., the amount required for the growth of β-Ga2O3) was clarified. On the basis of this pyrolysis/combustion behavior, homoepitaxial growth of β-Ga2O3 layers on β-Ga2O3 substrates was investigated at 1000 °C using Et2GaOEt as a Ga precursor and the growth behavior was compared with that when triethylgallium (Et3Ga) was used as a Ga precursor. Because both Ga precursors ultimately provide Ga gas after β-H elimination, no substantial difference in the growth rate was observed with respect to the amount of Ga atoms injected into the growth reactor. In addition, no substantial difference in crystallinity was observed; homoepitaxial layers grown at 0.7—0.8 μm/h were single crystals without twins, whereas those at 1.5—1.6 μm/h had twins. Et2GaOEt was found to be suitable as a Ga precursor for MOVPE of β-Ga2O3, with performance comparable to that of Et3Ga. [ABSTRACT FROM AUTHOR]

To improve the photocatalytic performance of semiconductor catalysts, one of the most widely used strategies is to combine two or more semiconductors with appropriate energy band structures to construct heterojunctions for an extended light absorption range and effective charge separation. Here, a novel Z-scheme heterojunction is fabricated via the Cd0.3Zn0.7S twin crystal and the narrow band gap semiconductor Ag3PO4. The resulting Cd0.3Zn0.7S/1%Ag3PO4 photocatalyst exhibits excellent photocatalytic hydrogen production capability (167.29 μmol h−1), which is two times higher than that of Cd0.3Zn0.7S and 44/7 times higher than that of pristine ZnS/CdS. The excellent photocatalytic performance is not only attributed to the defective twin crystal structure of Cd0.3Zn0.7S but also related to the well-matched Z-scheme interface between Cd0.3Zn0.7S and Ag3PO4, and both factors effectively promote the separation of the photogenerated electron–hole pairs and prolong the lifetime of the carriers, being responsible for the excellent photocatalytic hydrogen evolution performance of the catalysts. This strategy provides new insights into the construction of efficient twin crystal heterojunctions for photocatalytic hydrogen evolution with high performance. [ABSTRACT FROM AUTHOR]

Highly b‐oriented MFI zeolite (abbreviated as BOMZ) membranes are attractive due to less grain boundary defects and straight channels normal to the substrate, enhancing selectivity and flux in membrane separation. Herein, we demonstrate a novel, effective and easily‐amplified printing‐transfer oriented‐seed‐layer technique to manufacture uniform BOMZ seed monolayer on porous supports. Furthermore, a facile and effective approach for the synthesis of highly BOMZ membranes by introducing poly(hexamethylene biguanide) hydrochloride as a twin crystal inhibitor during seeded growth is demonstrated. Well‐intergrown BOMZ membranes (∼650 nm thick) obtained on porous Al2O3 supports show a flux of 2.8 kg m−2 h−1 with a separation factor as high as 71 for pervaporation in the 60 °C feed of EtOH/H2O (5 wt%), which is much higher than those of random membranes. The developed seed assembly technique on porous supports underlines great potential for facile preparation of oriented seed layers on porous supports. [ABSTRACT FROM AUTHOR]

Synthetic single crystals of K[(CuII,MnII,MnIII)2(TeO3)3]·2H2O were obtained from an overconcentrated alkaline aqueous solution in the system K2O-MnO-CuO-TeO2 under hydrothermal conditions at T ≤ 220 °C. Subeuhedral single crystals have been investigated by means of single-crystal X-ray diffraction. The crystal structure of this new zemannite-type representative adopts a monoclinic twofold superstructure. The doubling of the unit-cell volume is accompanied by a hexagonal-to-monoclinic symmetry reduction, resulting in threefold twinning with individual crystal domains following the space group symmetry P21. Refinements of site-occupation factors and the evaluation of bond valences suggest a distribution of di- and trivalent cations at the octahedrally coordinated M sites with a ratio (CuII + MnII):MnIII approximating 1:1. Based on arguments about the cation sizes and the individual bond valence sums, a distribution of CuII1–xMnIIIx and MnIIx MnIII1–x at each two of the four M sites can be assumed with x between ~ 0.14 and ~ 0.50. The K+ cations and H2O molecules inside the channels are located off the central channel axis. In contrast to most other known zemannite-type phases, the extra-framework atoms show full occupancies and are not disordered. The distribution of the channel contents supports the anisotropic deformation of the surrounding framework, which follows the local symmetry reduction as required for the Jahn-Teller distortion of the octahedrally coordinated M sites within the framework. The arrangement of the deformed channels can be understood as the origin of the existing superstructure. [ABSTRACT FROM AUTHOR]

Yellow needles-like single crystals of Li4P2S6 were obtained serendipitously during the preparation of Li7P3S10O. The twinned crystal structure of Li4P2S6 was determined from single-crystal X-ray diffraction data [wR(F2) = 0.069, 716 reflections, 40 variables]. Li4P2S6 crystallizes in the trigonal system, space group P 3 ‾ m 1 (N° 164), a = 10.5042(8) Å, c = 6.5837(6) Å, V = 629.11(9) Å3 and Z = 2. The lithium octahedra form a [Li4S6]8− honeycomb-like structure within which diphosphate units are located. The comparison of our crystal structure to those of P63/mcm-, P 3 ‾ 1 m -, and P321-Li4P2S6 demonstrated group-subgroup relationships and associated the disorder or order of the phosphorus atoms within the identical [Li4S6]8− 3d-frameworks to the choice of the unit cell (the subcell with a ∼ 6.07 Å vs. the supercell with a ∼ 10.5 Å). [ABSTRACT FROM AUTHOR]

Yellow needles-like single crystals of Li4P2S6 were obtained serendipitously during the preparation of Li7P3S10O. The twinned crystal structure of Li4P2S6 was determined from single-crystal X-ray diffraction data [wR(F2) = 0.069, 716 reflections, 40 variables]. Li4P2S6 crystallizes in the trigonal system, space group P 3 ‾ m 1 (N° 164), a = 10.5042(8) Å, c = 6.5837(6) Å, V = 629.11(9) Å3 and Z = 2. The lithium octahedra form a [Li4S6]8− honeycomb-like structure within which diphosphate units are located. The comparison of our crystal structure to those of P63/mcm-, P 3 ‾ 1 m -, and P321-Li4P2S6 demonstrated group-subgroup relationships and associated the disorder or order of the phosphorus atoms within the identical [Li4S6]8− 3d-frameworks to the choice of the unit cell (the subcell with a ∼ 6.07 Å vs. the supercell with a ∼ 10.5 Å). [ABSTRACT FROM AUTHOR]

Large size nickel-based single crystal twin turbine guide vanes (TGVs) were prepared by grain continuator (GC) technology. Directional solidification was performed in a high-rate-solidification (HRS) Bridgman vacuum furnace. Then, the macroetching test was carried out to reveal the single crystal integrality of TGVs. Scanning electron microscopy (SEM), electron backscatter diffraction (EBSD) technology, and high temperature stress rupture experiment were applied to evaluate the actual properties of TGVs. Simultaneously, the professional finite element modeling (FEM) ProCAST software was used to simulate the directional solidification process of single crystal TGVs. The experimental results show that the formation of stray grain (SG) defect can be avoided effectively, and integrity large size single crystal twin TGVs can be prepared successfully by adopting GC technology. However, the low angle grain boundaries (LABs) defects are formed inevitably, and the boundaries angle between primary crystal and GC crystal in Vane 1 are 1.5° and 2.7° respectively. Despite the mechanical performance at high temperature degrades slightly (stress rupture life loss less than 15%, and elongation loss less than 7%), the service performance of TGVs is still satisfied perfectly. According to the solidification process results of the large size twin TGVs simulated by ProCAST software, it is found that the initial solidification path of TGVs is optimized, meanwhile, and the undercooling condition at the leading edge of TGVs is improved by adding the GC structure. In addition, the nucleation probability of SG defect is reduced significantly, and the formation of SG defects is avoided effectively. [ABSTRACT FROM AUTHOR]

The presence of MFI twin crystals on b-axis oriented zeolite MFI nanosheet films was suppressed by adding dihydroxy-benzene isomers in the synthesis mixture. The resulting nanosheet films exhibit good intergrowth and a small grain thickness of 30–45 nm within a relatively short synthesis time (hours). The possible twin suppression mechanisms for the three isomers are discussed. [ABSTRACT FROM AUTHOR]

Biogenic twinning β-phase anhydrous guanine nanoplatelets are utilized as optical materials in organisms. However, it is still a puzzle how to produce crystalline guanine platelets in aqueous solutions since guanine has a low solubility in water. Herein, the controlled synthesis of twinning guanine nanoplatelets was realized for the first time in an aqueous solution in the presence of poly(1-vinylpyrrolidone-co-vinyl-acetate) via ammonia volatilization. The synthesized rectangular twinning guanine nanoplatelets with an exposed (100) face were β-form anhydrous guanine (β-AG), and the twinning angle of the two c-axes was about 83°, similar to the biogenic twinning β-AG nanoplatelets. The length and thickness of the twinning β-AG nanoplatelets were about 2 μm and 42 ± 3 nm, respectively. There were about five to seven layers observed for the synthesized twinning β-AG nanoplatelets, with each layer being as thin as 6 ± 2 nm. It was proposed that amorphous guanine particles are formed as intermediate precursors, which dissolve and recrystallize to single-crystalline β-AG nanoplatelets, and then multilayered twinning β-AG nanoplatelets are formed via π–π interaction with the assistance of the guanine-quartet assembly. The obtained twinning β-AG exhibited a high reflection intensity in the visible and near infrared region and a brilliant pearlescent luster, indicating that they could potentially be applied as optical materials. This work provides a new design strategy to synthesize particular organic molecular crystals with low solubility in water and a novel formation mechanism for twinning organic crystals. [ABSTRACT FROM AUTHOR]

The temperature dependences of both fluctuation conductivity (FLC) σ′(T) and pseudogap (PG) Δ*(T) derived from measurements of resistivity ρ(T) of an optimally doped YBa2Cu3O7−δ single crystal subjected to long-term storage have been studied. The as-grown sample S1 exhibits characteristics typical of optimally doped YBa2Cu3O7−δ single crystals containing twins and twin boundaries. Analysis of both FLC and PG showed an unexpected improvement in all characteristics of the sample after 6 years of storage (sample S2), indicating that the effect of twin boundaries is somehow limited. After 17 years of storage, all characteristics of the sample changed dramatically, which indicates a strong influence of internal defects formed during the aging process. For the first time, the temperature dependences of both FLC and PG were obtained after 17 years of storage. [ABSTRACT FROM AUTHOR]

The purposes of this study were: (1) to review the preparation and characterization of the intergrowth between goethite and hematite crystals; and (2) to propose a schematic diagram of the epitaxial relationships among three sets of (100) goethite twin crystals associated with the (001) orientation of the hexagonal prism of hematite. The Fe(ClO4)3 solution was prepared and aged at 70°C, which precipitated goethite initially and produced hematite later with prolonged aging. Goethite and hematite aged for 20 days were observed as star-shaped and hexagonal prisms, respectively. The results suggest that hematite could form later using goethite as a template surface. A selected area electron diffraction (SAED) pattern showed the epitaxial relationship among three sets of (100) goethite intergrowth crystals and hexagonal prisms with the (001) orientation of hematite. Goethite can be produced as lath-, X-, K-, or star-shaped crystals on the (100) orientation, depending on the Fe(ClO4)3 concentrations and the addition of HClO4 to Fe solution samples which were aged for a prolonged period at room temperature. The initial solubility products [(Fe3+)(OH–)3] of the sample solution, rather than the nature of the nuclei, are the key factors governing the formation of goethite or hematite. The addition of acids and high concentrations of iron solutions extend the secondary hydrolysis and induction period (IP) and favor the formation of hematite. The index of the SAED pattern of the star-shaped goethite intergrowth twin crystal has a (100) plane parallel to this basal plane and rotates at a 60° angle between two or three sets of lath-shaped goethite crystals, which share the (011) plane and form goethite twins with 'interpenetrated' crystal growth. Stereoscopic viewing using Oak Ridge Thermal Ellipsoid Plot (ORTEP) and CrystalMaker software was deployed to explore the relationship and configuration of oxygen atoms between pseudo-hexagonal (100) goethite associated with hexagonal (001) hematite lattice planes. A schematic diagram of the epitaxial relationship between star-shaped (100) goethite, which is acting as a template facilitating later precipitation of (001) hexagonal prisms of hematite on it, is presented. [ABSTRACT FROM AUTHOR]

Understanding and controlling the development of deformation twins is paramount for engineering strong and stable hexagonal close-packed (HCP) Mg alloys. Actual twins are often irregular in boundary morphology and twin crystallography, deviating from the classical picture commonly used in theory and simulation. In this work, the elastic strains and stresses around irregular twins are examined both experimentally and computationally to gain insight into how twins develop and the microstructural features that influence their development. A nanoprecession electron diffraction (N-PED) technique is used to measure the elastic strains within and around a 10 1 ¯ 2 tensile twin in AZ31B Mg alloy with nm scale resolution. A full-field elasto-viscoplastic fast Fourier transform (EVP-FFT) crystal plasticity model of the same sub-grain and irregular twin structure is employed to understand and interpret the measured elastic strain fields. The calculations predict spatially resolved elastic strain fields in good agreement with the measurement, as well as all the stress components and the dislocation density fields generated by the twin, which are not easily obtainable from the experiment. The model calculations find that neighboring twins, several twin thicknesses apart, have little influence on the twin-tip micromechanical fields. Furthermore, this work reveals that irregularity in the twin-tip shape has a negligible effect on the development of the elastic strains around and inside the twin. Importantly, the major contributor to these micromechanical fields is the alignment of the twinning shear direction with the twin boundary. [ABSTRACT FROM AUTHOR]

The unusual shape of the Matryoshka diamond, which is a diamond crystal with a cavity containing a diamond crystal freely moving in it, continues to attract keen interest of many researchers in the context of its seemingly paradoxical origin for a mantle mineral. The discovery sparked lively discussions and multiple attempts to explain the nature of the unique shape of this crystal. A comprehensive mineralogical and crystallographic analysis of the unusual specimen, as well as other analogous diamond crystals, suggests that it was formed as a consequence of the mutual disorientation of the crystals during their growth and the presence of a twin of diamond subindividuals that formed both the core (inclusion) and the sheath (host) diamonds. The twinning planes (111) in the contacting crystals of the inclusion and the host were in a sub-perpendicular position to each other during their simultaneous growth. The captured diamond of the inclusion prevented the normal development of the diamond that became the host. The diamond host rapidly grew along the direction of its own twin boundary and constantly generated new growth layers, which eventually converged around the small captured twin crystal cluster during metric selection. Analysis of diamond crystals of similar shape from the Nyurbinskaya pipe and from elsewhere worldwide confirms the ontogenic model of their origin as a consequence of the capture of diamond inclusions that hampered the rapid growth of the twin crystal (spinel-law twins) in the direction of the twin boundary. [ABSTRACT FROM AUTHOR]

In general, crystal twinning in accessory zircon represents a rare, but in almost all granites and gneisses, encounterable phenomenon. Since only the crystal face {101} occurs as a twin plane, formation of crystal twins turns out to be relatively simple. Besides geniculate twins, which develop by rotation of the crystal structure about the line [101], parallel twins that are arranged parallel to the crystallographic main axis of zircon can also be observed by light and electron microscopy. While geniculate twins usually show a frequency within the region of a permille, the number of parallel twins can rise to several percent depending on the investigated rock. In the present contribution, a brief insight into the microscopic world of zircon twinning is provided. [ABSTRACT FROM AUTHOR]

This document is an editorial from the Zeitschrift für Kristallographie – New Crystal Structures journal, discussing recent developments and changes. The editorial highlights the addition of new members to the editorial team, including experts in crystal structure determination and non-standard conditions. It also mentions the retraction of two articles from 2009 due to the lack of diffraction data and the introduction of rules for article titles and minimizing the mention of applications. The editorial emphasizes the importance of providing structural and crystallographic background information and mentions the acceptance of improved structure determinations. Technical changes, such as the use of the ACS numbered reference style and the implementation of automated tools for publication processes, are also mentioned. The editorial concludes by acknowledging the progress in crystal structure determination and the continued need for quality crystal structures. [Extracted from the article]

Crystals of two new tetrafluoroborate crystallohydrates M(BF4)2·3H2O (M = Sr, Ba) are prepared by the evaporation of aqueous solutions. The compounds are studied by single crystal XRD and IR spectroscopy. Sr(BF4)2·3H2O crystallizes in the tetragonal crystal system (a = 6.9638(4) Å, c = 18.1671(12) Å, space group P42/mnm); Ba(BF4)2·3H2O crystallizes in the orthorhombic crystal system (a = 7.1996(2) Å, b = 18.0823(5) Å, c = 7.1860(2) Å, space group C2221). Their crystal structure is formed by isolated BF4 tetrahedra and water molecules with alkaline earth metal atoms in between. When cooled to 100 K, Ba(BF4)2·3H2O undergoes a polymorphic transition to the monoclinic modification accompanied by pseudo-merohedral twinning of crystals. [ABSTRACT FROM AUTHOR]

Two examples of contact twins in pyrite from Peru are described. The first one, from Pasto Bueno ore deposit, shows the pyritohedron {120} as principal form, accompanied by the {111} octahedron and {100} cube as secondary forms, giving a lenticular aspect. (111) is the composition plane, and the twin operation is any one of the three binary axes ⟨110⟩ within this plane. The second one (unknown ore deposit) presents two forms, the octahedron {111} and the pyritohedron {120}; the two crystals in the twin are elongated along [101] and [011], respectively, producing a V profile. It is a reflection twin where the twin plane (110) coincides with the composition plane. These twins are by merohedry. Another contact twin is known in the literature, reported by Gaubert [Bull. Soc. Fr. Minéral. Cristallogr. (1928), 51, 211–212] who described it as a spinel twin, i.e. a reflection twin with twin and composition plane (111); here it is shown that it is actually a rotation twin in which the twin operation is a 180° rotation about any of the three equivalent directions ⟨211⟩, contained in the (111) composition plane. The occurrence of these twins as well as the doubtfulness of the spinel twin in pyrite shows a direct relationship with the structural interpretation based on the pseudo‐symmetry of the crystallographic orbits. [ABSTRACT FROM AUTHOR]

The effect of annealing at room temperature on the fluctuation conductivity (FLC) σ′(T) and pseudogap (PG) Δ*(7) in the basal ab plane of ReBa2Cu3O7–δ (Re = Ho) single crystals with a lack of oxygen has been studied. It is shown that at all stages of annealing, the FLC near Tc can be described by the Aslamazov-Larkin and Maki-Thompson fluctuation theories, demonstrating a 3D-2D crossover with increasing temperature. The crossover temperature T0 was used to determine the coherence length along the c axis, ξc(0) = (2.82 ± 0.2) Å. At the intermediate stage of annealing, an anomalous increase in 2D FLC was revealed, which is associated with the influence of uncompensated magnetic moments in HoBa2Cu3O7–5 (HoBCO): μeff, Ho = 9.7μΒ. For the quenched sample S1, the temperature dependence of the PG has a shape typical of single crystals with a large number of defects. However, Δ*(T) has two small additional maxima at high temperature, which is a feature of HoBCO single crystals with pronounced twins and indicates the two-phase nature of the sample. Upon annealing, the shape of Δ*(T) noticeably changes, very likely due to an increase in the magnetic interaction (sample S2). More important is the change in the slope of the data at high temperatures, which has become about 3.5 times steeper. The ordering of the oxygen distribution due to the diffusion process during annealing somewhat compensates for the influence of magnetic interaction. But the slope does not change (sample S3). Interestingly, the slope turns out to be the same as for FeAs-based superconductors, suggesting the possibility of the existence of spin density waves in HoBCO in the PG state. The comparison of the pseudogap parameter Δ ∗ (T) / Δ max ∗ near Tc with the Peters-Bauer theory revealed a slight increase in the density of local pairs < n↑n↓>, which should explain the observed increase in Tc by 9 K during annealing. [ABSTRACT FROM AUTHOR]

We fabricate Bi 1−x-y Pb y Cu 1−x SeO (x = 0, 0.03, 0.06, y = 0, 0.10) samples via 4 min-microwave synthesis combined with 5 min-spark plasma sintering. The phase composition, microstructure, valence, and electrical and thermal transport properties of the samples are investigated at 298–873 K. Pb doping provides impurity carriers and increases the concentration to 0.9–3.0 × 1020 cm-³. Bi and Cu vacancy could provide a carrier transport channel to reduce carrier scattering probability, leading to improved mobility. Twin crystals, stacking faults, and grain boundary segregation are observed in Bi 0.87 Pb 0.10 Cu 0.97 SeO on scanning transmission electron microscopy. Bi and Cu vacancy increase the sample point defects in Pb-doped or undoped samples which results in a decrease in lattice thermal conductivity. The lattice thermal conductivity of Bi 0.87 Pb 0.10 Cu 0.97 SeO is decreased to an extremely low value of 0.13 Wm−1 K−1 and a maximum ZT value of 1.09 is achieved at 873 K. [ABSTRACT FROM AUTHOR]

We performed density functional theory (DFT) calculations on binary and ternary oxo/fluoro crystals of the geochemical twin pair zirconium and hafnium to evaluate and compare their stabilities. This is the first DFT study on bulk ZrF4 or HfF4, as well as on a hypothetical ZrOF2 or HfOF2 bulk crystal. For α-MO2, β-MF4 and MOF2, we have found significantly higher cohesive energies for the respective hafnium species. This suggests a considerable gap in affinity toward fluorine and oxygen between the twin pair in the solid state. In agreement with experimental findings, this gap is slightly more pronounced for fluorine. This study is also the first to evaluate the theoretical, endothermic mono-hydroxylation of the respective fluorides or oxyfluorides to model the difference in affinity toward fluoride versus hydroxide. For these, we could also find a slight energetic preference for the hafnium compound. [ABSTRACT FROM AUTHOR]

The euhedral shapes of pyrite FeS2 are usually exposing three main surfaces: striated (001), smooth (111), and striated (210), leading to the cubical, octahedral, and pyritohedral morphology, respectively. The macroscopic striations, sometimes called triglyphs on cubic crystals, are parallel on specific surfaces and aligned to the <100> directions. Other types of striated and unstriated (hkl) surfaces can be observed on pyrite crystals from Peru, a country offering a rich diversity of pyrite shapes. A rare specimen from Elba Island (Italy) is a pyritohedron with uncommon directions of striations (so-called "negative" striations, first described in Japanese minerals). The Wulf kinetic growth and the periodic bond chain (PBC) theories were not relevant enough to explain crystal shapes, the texture of the surfaces, and twinning. To bring some new insights on crystal growth, twinning, and anisotropy, pyrite samples are analyzed using XRD, SEM, and EDS techniques coupled with atomistic simulations. A first analysis points out that sulfur terminations play a key role in the growth of striations in distinguishing the six <001> directions. The negative striated pyritohedral pyrite would be, in fact, a special case that has stabilized the {120} surfaces, which are structurally different from the {210} facets. The {120} surface has a slightly higher surface energy than the {210} surface (surface energies of 1.68 and 1.65 J/m2, respectively, calculated with force field methods). {120} pyritohedra from Elba, Italy, are growing next to micaceous iron oxides (a type of hematite), which are also peculiar specimens with magnetic properties. Another specificity is that some rare earth elements have been identified in the pyrite sample from Elba, which leads to a hypothesis that geothermal conditions favor "negative" striations (e.g., discernible in Akita prefecture-Japan, Boyacá-Colombia, and Cassandra-Greece). The striation directions become useful to distinguish (hkl) surfaces and to identify twinning as they follow the same patterns on each interpenetrated crystal. The most common twinning is the "iron cross," a penetration twin of two crystals defined by a rotation of 90° along an [001] axis with a coincidence in the iron sub-lattice (e.g., twinning by merohedry) and with a twin center. The sulfur network also plays a fundamental role in stabilizing the (001) interface and in keeping the chemical bulk properties at the boundary, as confirmed by additional ab initio simulations. The grain boundary is a 2D defect in which the (001) twinning is relatively stable as it is common. The calculated formation energy of the rotation twinning is 0.8 J/m2. The rotation twinning is associated with an apparent reflection on (110) planes. The formation energy of the (110) mirror grain boundary is 1.7 J/m2, and the interface at the atomic scale is relatively uniform in agreement with experimental observations. [ABSTRACT FROM AUTHOR]

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With the increase in lightweight components, Al-Si-Cu alloys are extensively applied in the automotive field. In this study, a multi-principal element alloy (MPEA) AlZrNiTi was designed to modify the Al-9Si-3Cu alloy, and the modification effects of individual additions of Zr, Ni, and Ti elements to the alloy were assessed. Moreover, the microstructure evolution, fracture behavior, and the mechanisms of strengthening and toughening during the modification process were investigated. Experimental results showed that when the addition amount of AlZrNiTi alloy was 0.8 wt%, significant refinements were made to the α-Al, eutectic Si, and Al 2 Cu in the Al-9Si-3Cu alloy, and the mechanical properties were significantly improved. In addition, the AlSiZr phase served as the heterogeneous nucleation core of α-Al was discovered. Furthermore, the AlZiTi phase was enriched at the front edge of the solid-liquid interface in solidification, hindering the growth of α-Al grains. It was also found that Al(Ni, Cu) particles with a size of 336 nm promoted the formation of high-density twins in Si crystal through the impurity-induced twin (IIT) mechanism, thereby modifying the Si phase. Comparative experiments reveal that the modification effect and mechanical properties of AlZrNiTi master adding to Al-9Si-3Cu alloy was obviously better than that of individual adding Zr, Ni, and Ti elements. • The effect of the addition of AlZrNiTi master alloy on the microstructure and mechanical properties of Al-9Si-3Cu alloy was investigated. Correspondingly, the mechanisms of strengthening and toughening during the modification process were investigated. • The α-Al, Al 2 Cu, and eutectic Si of the Al-9Si-3Cu alloy underwent significant refinement and modification after the addition of 0.8 wt% AlZrNiTi master alloy. • The El, UTS, and YS were increased from 4.05 %, 206 MPa, and 90.8 MPa to 6.2 %, 254 MPa, and 119.5 MPa, compared with the unmodified Al-9Si-3Cu alloy. Comparative experiments reveal that the modification effect of adding AlZrNiTi master alloy is much better than that of individually adding Zr, Ni, and Ti elements. [ABSTRACT FROM AUTHOR]

The influence of graphene layers and crystal structure types on the nanoindentation reinforcement mechanism of Al 0.3 CoCrFeNi high-entropy alloy/graphene (HEA/Gp) composite materials was studied using molecular dynamics (MD) simulations. The results indicate that the influence of graphene layers on composite materials is related to the position of the indenter. Before the indenter contacts the graphene layer, some dislocations are absorbed by the graphene, unable to form dislocation cells and dislocation locks to hinder the deformation of the matrix, resulting in the hardness of the composite material being lower than that of the HEA matrix. After the indentation contacts the graphene layer, dislocations can penetrate the graphene to form a high-density dislocation cell. Due to graphene's excellent deformation resistance, the composite material's load-bearing capacity is much greater than that of the HEA matrix. In addition, stress propagates along the grain boundaries in polycrystalline and twinned polycrystalline structures. Grain boundaries decrease the material strength, while twinned boundaries can refine grain size and enhance grain stability. Additionally, composite materials' elastic recovery increases first and then decreases with the increase in graphene layers and twinning. The hardness of the material shows an anomalous phenomenon about grain size following a Hall-Petch relationship. When the angle between graphene layers is 0, the stress distribution inside the material is most uniform. • The change in hardness and mechanism of composite materials is studied before and after contact with the indenter and graphene. • Grain boundaries reduce the material strength, while twin boundaries can refine the grains and improve grain stability. • The influence of graphene layers, grain size, twin crystal number, and interlayer angles of graphene on composite materials is being studied. • After loading and unloading pressure, the change of the C-C bond was analyzed. [ABSTRACT FROM AUTHOR]

The predominant crystallographic relationships between recrystallization nuclei and deformation structures have been characterized in aluminum single crystals (ASCs) of <001> − orientation. Some microband (MB) groups parallel to the active slip plane {111} were found in the unidirectional torsion ASCs, which will lead to recrystallization after annealing. The misorientations of recrystallized grains are grouped in the range of 30°-60°, which are generated by the rotation of adjacent deformed matrix around the 〈111〉, 〈122〉 and 〈112〉 directions. In addition, the preferred misorientations of recrystallization around four normals to the {111} planes are distributed from 30°-40°, and gradually predominates with increased strain and annealing temperature. Unexpectedly, ∑3 twin boundaries (TBs) were nucleated by the grain boundary dissociation and grain encountering mechanism during static recrystallization (SRX), and the grain boundary dissociation mechanism was more apparent with strain due to the increased grain boundary energy. Grain refinement and directional grain growth are potential by controlling the number of annealing twins, which can provide a new method for improving the properties of Al alloys. [Display omitted] • The microstructure evolution of aluminum single crystal during torsion deformation was firstly investigated. • The nucleation mechanism of annealing twins was described in detail. • The orientation relationship between recrystallized grains and deformed matrix was discussed. [ABSTRACT FROM AUTHOR]

The dynamics of { 1 0 1 ‾ 2 } 〈 1 0 1 ‾ 1 〉 extension twins in a single crystal of pure magnesium are studied through uniaxial compression experiments coupled with direct optical imaging. The experiments covered a seven orders of magnitude strain rate, between 10 − 5 − 10 2 s − 1 , covering all rates of engineering applications of magnesium and its alloys. Under uniaxial compression along a direction perpendicular to prismatic planes, only two variants of extension twins are activated, facilitating in-situ tracking of individual twin boundaries throughout the deformation process. Across the entire strain rate range, the twinning transformation evolves in a self-similar pattern of twin nucleation and thickening. Deformation fronts initiate at the edges of the sample and propagate toward the center, creating parallel twins with characteristic thicknesses and distances from each other. The velocity of the deformation fronts scales linearly with the imposed external strain rate and a nearly uniform resolved shear stress is measured over the entire strain rate range. We show that this unique process is attributed to the constant ratio between the nucleation rate and sideways velocity of individual twin boundaries, where both processes are proportional to the imposed strain rate. These findings indicate that, within the large strain rate range investigated in this study, the evolution mechanism of extension twinning is practically rate-independent. [Display omitted] [ABSTRACT FROM AUTHOR]

The magnetomechanical behavior of ferromagnetic shape memory alloys such as Ni-Mn-Ga, and hence the relationship between structure and nanoscale magnetomechanical properties, is of interest for their potential applications in actuators. Furthermore, due to its crystal structure, the behavior of Ni-Mn-Ga is anisotropic. Accordingly, nanoindentation and magnetic force microscopy were used to probe the nanoscale mechanical and magnetic properties of electropolished single crystalline 10M martensitic Ni-Mn-Ga as a function of the crystallographic c-axis (easy magnetization) direction relative to the indentation surface (i.e., c-axis in-plane versus out-of-plane). Load-displacement curves from 5–10 mN indentations on in-plane regions exhibited pop-in during loading, whereas this phenomenon was absent in out-of-plane regions. Additionally, the reduced elastic modulus measured for the c-axis out-of-plane orientation was ∼50% greater than for in-plane. Although heating above the transition temperature to the austenitic phase followed by cooling to the room temperature martensitic phase led to partial recovery of the indentation deformation, the magnitude and direction of recovery depended on the original relative orientation of the crystallographic c-axis: positive recovery for the in-plane orientation versus negative recovery (i.e., increased indent depth) for out-of-plane. Moreover, the c-axis orientation for out-of-plane regions switched to in-plane upon thermal cycling, whereas the number of twins in the in-plane regions increased. We hypothesize that dislocation plasticity contributes to the permanent deformation, while pseudoelastic twinning causes pop-in during loading and large recovery during unloading in the c-axis in-plane case. Minimization of indent strain energy accounts for the observed changes in twin orientation and number following thermal cycling. [ABSTRACT FROM AUTHOR]

Twin crystals, the formation energy of which is much smaller than that of ordinary grain boundaries, widely exist in the annealed copper and are hard to eliminate. The study of the effects of twin boundaries on graphene growth is of great significance to the understanding of graphene epitaxy. However, there are few studies on the effects of twin boundaries on the graphene growth process. Here, this article experimentally demonstrates that graphene islands are subjected to different compressive strains from the opposite copper crystal plane after growing across the twin boundary. Further results reveal that graphene can grow across different twin boundaries, such as atom steps, narrow valleys, and even micron‐scale ridges, without forming linear defect. Therefore, strain‐induced graphene doping can be manipulated with the type of twin boundaries and the location on the twin crystals. The transition region where the degree of doping changes monotonically across the twin boundary further confirms the different spatial doping phenomena of graphene islands. This work provides a new perspective for understanding the effect of twin boundaries on the graphene epitaxy, which is expected to have a potential impact on growing high‐quality graphene on twinned copper substrates. [ABSTRACT FROM AUTHOR]

This study introduces a new chemical method for controlling the strain in methylammonium lead iodide (MAPbI3) perovskite crystals by varying the ratio of Pb(Ac)2 and PbCl2 in the precursor solution. To observe the effect on crystal strain, a combination of piezoresponse force microscopy (PFM) and X‐ray diffraction (XRD) is used. The PFM images show an increase in the average size of ferroelastic twin domains upon increasing the PbCl2 content, indicating an increase in crystal strain. The XRD spectra support this observation with strong crystal twinning features that appear in the spectra. This behavior is caused by a strain gradient during the crystallization due to different evaporation rates of methylammonium acetate and methylammonium chloride as revealed by time‐of‐flight secondary ion mass spectroscopy and grazing incidince X‐ray diffraction measurements. Additional time‐resolved photoluminescence shows an increased carrier lifetime in the MAPbI3 films prepared with higher PbCl2 content, suggesting a decreased trap density in films with larger twin domain structures. The results demonstrate the potential of chemical strain engineering as a simple method for controlling strain‐related effects in lead halide perovskites. [ABSTRACT FROM AUTHOR]