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The B20 type chiral magnet FeGe exhibits the formation of skyrmion-lattice (SkL) phases in the vicinity of the magnetic ordering temperature. The SkL is a magnetic superlattice composed of vortex-type topological spin objects, and it has experimentally been known that its formation requires the existence of an intermediate (IM) phase between SkL and the paramagnetic (PM) phases. We take interest in how the crystal lattice experiences the formation of these topological spin texture. In this study, we observed the so-called spin–orbit coupling induced magnetostriction related to these topological spin texture formation, in addition to the ac magnetization anomalies. The temperature and magnetic field dependences of the lattice parameter reflected the transformation of phases, such as helimagnetic (HM), SkL, IM, conical (CM), and PM phases. In the PM region, a phase characterized as gaseous skyrmions was detected similarly to the case of the same B20 type MnSi. Furthermore, the HM, CM, and IM phases were also divided into two regions. Thus, the precise phase diagram near T c was reconstructed from the prospect of the magnetostriction such that we demonstrated that the stabilization of skyrmions needs a finite magnetic field. [ABSTRACT FROM AUTHOR]

Basal plane dislocations (BPDs) are a key factor influencing the advancement of the 4H-SiC semiconductor. In this paper, the effects of shear forces on the nucleation and movement of BPDs are revealed by employing molecular dynamics simulations. The stress–strain curves of 4H-SiC subjected to different shear forces at different temperatures are obtained. It is found that the decrease in mechanical properties of 4H-SiC is mainly due to the occurrence of dislocation. This study also delves into the complexities of dislocation entanglement and slip, unraveling the impact on the mechanical properties of 4H-SiC. Moreover, the causes of dislocation within the crystal lattice were clarified from a microscopic atomic vantage point, shedding light on the intricate mechanisms involving chemical bond rupture and regeneration. These findings not only enrich our understanding of BPDs nucleation but also provide invaluable insights for mitigating BPDs in 4H-SiC. [ABSTRACT FROM AUTHOR]

Upon osmotic compression, rotationally symmetric faceted colloidal particles can form translationally ordered, orientationally disordered rotator mesophases. This study explores the mechanism of rotator-to-crystal phase transitions where orientational order is gained in a translationally ordered phase, using rotator-phase forming truncated cubes as a testbed. Monte Carlo simulations were conducted for two selected truncations (s), one for s = 0.527 where the rotator and crystal lattices are dissimilar and one for s = 0.572 where the two phases have identical lattices. These differences set the stage for a qualitative difference in their rotator–crystal transitions, highlighting the effect of lattice distortion on phase transition kinetics. Our simulations reveal that significant lattice deviatoric effects could hinder the rotator-to-crystal transition and favor arrangements of lower packing fraction instead. Indeed, upon compression, it is found that for s = 0.527, the rotator phase does not spontaneously transition into the stable, densely packed crystal due to the high lattice strains involved but instead transitions into a metastable solid phase to be colloquially referred to as "orientational salt" for short, which has a similar lattice as the rotator phase and exhibits two distinct particle orientations having substitutional order, alternating regularly throughout the system. This study paves the way for further analysis of diffusionless transformations in nanoparticle systems and how lattice-distortion could influence crystallization kinetics. [ABSTRACT FROM AUTHOR]

First-principles calculations were employed to investigate the impact of quantum ionic fluctuations and lattice anharmonicity on the crystal structure and superconductivity of Pm 3 ̄ AlM(M = Hf, Zr)H6 at pressures of 0.3–21.2 GPa (AlHfH6) and 4.7–39.5 GPa (AlZrH6) within the stochastic self-consistent harmonic approximation. A correction is predicted for the crystal lattice parameters, phonon spectra, and superconducting critical temperatures, previously estimated without considering ionic fluctuations on the crystal structure and assuming the harmonic approximation for lattice dynamics. The findings suggest that quantum ionic fluctuations have a significant impact on the crystal lattice parameters, phonon spectra, and superconducting critical temperatures. Based on our anharmonic phonon spectra, the structures will be dynamically stable at 0.3 GPa for AlHfH6 and 6.2 GPa for AlZrH6, ∼6 and 7 GPa lower than pressures given by the harmonic approximation, respectively. Due to the anharmonic correction of their frequencies, the electron–phonon coupling constants (λ) are suppressed by 28% at 11 GPa for AlHfH6 and 22% at 30 GPa for AlZrH6, respectively. The decrease in λ causes Tc to be overestimated by ∼12 K at 11 GPa for AlHfH6 and 30 GPa for AlZrH6. Even if the anharmonic and quantum effects are not as strong as those of Pm 3 ̄ n-AlH3, our results also indicate that metal hydrides with hydrogen atoms in interstitial sites are subject to anharmonic effects. Our results will inevitably stimulate future high-pressure experiments on synthesis, structural, and conductivity measurements. [ABSTRACT FROM AUTHOR]

Piezoresponse force microscopy (PFM) is one of the most widespread methods for investigating and visualizing ferroelectric domain structures down to the nanometer length scale. PFM makes use of the direct coupling of the piezoelectric response to the crystal lattice, and hence, it is most often applied to spatially map the three-dimensional (3D) near-surface domain distribution of any polar or ferroic sample. Nonetheless, since most samples investigated by PFM are at least semiconducting or fully insulating, the electric ac field emerging from the conductive scanning force microscopy (SFM) tip penetrates the sample and, hence, may also couple to polar features that are deeply buried into the bulk of the sample under investigation. Thus, in the work presented here, we experimentally and theoretically explore the contrast and depth resolution capabilities of PFM, by analyzing the dependence of several key parameters. These key parameters include the depth of the buried feature, i.e., here a domain wall (DW), as well as PFM-relevant technical parameters such as the tip radius, the PFM drive voltage and frequency, and the signal-to-noise ratio. The theoretical predictions are experimentally verified using x-cut periodically poled lithium niobate single crystals that are specially prepared into wedge-shaped samples, in order to allow the buried feature, here the DW, to be "positioned" at any depth into the bulk. This inspection essentially contributes to the fundamental understanding in PFM contrast analysis and to the reconstruction of 3D domain structures down to a 1 μ m-penetration depth into the sample. [ABSTRACT FROM AUTHOR]

Quartz-based minerals in earth's crust are well-known to contain water-related defects within their volume-constrained lattice, and they are responsible for strength-loss. Experimental observations of natural α -quartz indicate that such defects appear as hydroxyl groups attached to Si atoms, called Griggs defect (Si-OH), and molecular water (H 2 O) located at the interstitial sites. However, factors contributing to the formation of Griggs and interstitial H 2 O defects remain unclear. For example, the role of point defects like vacancy sites (O 2 − and Si 4 + ), and substitutional (Al 3 + ) and interstitial (Li + , K + , Ca 2 + , Mg 2 + , etc.) ions has remained largely unexplored. Here, we performed ab initio molecular dynamics at 300 K to examine the energetics and structure of water-related defects in volume-constrained α -quartz. Several configurations were systematically interrogated by incorporating interstitial H 2 O, O 2 − and Si 4 + vacancies, substitutional Al 3 + , and interstitial Li + , Ca 2 + and Mg 2 + ions within α -quartz. Interstitial H 2 O defect was found to be energetically favorable in the presence of Substitutional Al 3 + , and interstitial Ca 2 + , Mg 2 + , and Li 1 + . In the presence of O 2 − and Si 4 + vacancies, H 2 O showed a strong tendency to dissociate into OH—to form Griggs defect—and a proton; even in the presence of substitutional and interstitial ions. These ions distorted the α -quartz lattice and, in the extreme case, disrupted long-range order to form local amorphous domains; consistent with experimental reports. Our study provides an initial framework for understanding the impact of water within the crystal lattice of an anhydrous silicate mineral such as quartz. We provide not only thermodynamic and process-related information on observed defects, but also provides guidelines for future studies of water's impact on the behavior of silicate minerals. [ABSTRACT FROM AUTHOR]

In this work, the value and the polarity of the spontaneous and piezoelectric polarization have been investigated, as the use of two different reference structures for wurtzite-type group-III nitrides, namely, the zinc-blende and the layered-hexagonal crystal lattice, have resulted in different predictions. It was found that although the differences in value and polarity of the polarization for heterostructures such as wurtzite Al1−xScxN/GaN lead to similar interface sheet charges, a significant mismatch is observed when polarization reversal is considered. The interface sheet charge predicted before and after the polarization reversal in the wurtzite Al1−xScxN layer on GaN using the zinc-blende lattice as a reference predominantly shows a change in sign. When using the layered-hexagonal lattice as a reference, not only is the same polarity of the interface sheet charge maintained after polarization reversal, but it is even 30 times larger. In this case, the giant and positive spontaneous polarization values for metal-polar Al1−xScxN extracted from the ferroelectric switching, as well as the alignment of the piezoelectric polarization to it, were observed to be consistent with the predictions referenced to the layered-hexagonal lattice. Thus, it is concluded that the layered-hexagonal reference is not only more suitable for predicting the ferroelectric properties of wurtzite Al1−xScxN but should also be the correct reference when considering polarization reversal in heterostructures. If the significant increase in the interface sheet charge after polarization reversal is experimentally detected, it will allow the design and fabrication of novel devices for future high-frequency and power electronics applications. [ABSTRACT FROM AUTHOR]

Chemical pressure is widely applied to antiferroelectrics (AFEs) as a criterion to enhance their antiferroelectricity. However, NaNbO3 (NN)-based ceramic with well-defined double polarization hysteresis (P–E) loops was rarely reported based on this strategy, and the effect of chemical pressure on antiferroelectricity remains to be understood. In this work, the Me cations (Me is Ti, Sn, Zr) with different ionic radii were introduced into the component system 0.76NaNbO3–0.20AgNbO3–0.04CaMeO3 to tune the negative chemical pressure and investigate its effect on antiferroelectricity. The enhancement of negative chemical pressure can effectively stabilize the AFE phase and reduce hysteresis, as revealed by the P–E loops and dielectric properties, which is further confirmed by the change in crystal lattice parameters and in situ Raman spectra. Rietveld refinement of x-ray powder diffraction reveals that the enhanced negative chemical pressure mainly reduces the cation off-centering displacement and [BO6] octahedral tilting angles. As a result, the 0.76NaNbO3–0.20AgNbO3–0.04CaZrO3 exhibits good reversibility of the electric field-induced antiferroelectric–ferroelectric phase transition and well-defined double P–E loops. This work reveals the underlying mechanism of chemical pressure and provides an effective way of discovering new NN-based AFEs. [ABSTRACT FROM AUTHOR]

We employ the molecular dynamics simulations to study the dynamics of acetanilide (ACN) molecules placed on a flat surface of planar multilayer hexagonal boron nitride. We demonstrate that the ACN molecules, known to be achiral in the three-dimensional space, become chiral after being placed on the substrate. Homochirality of the ACN molecules leads to stable secondary structures stabilized by hydrogen bonds between peptide groups of the molecules. By employing molecular dynamics simulations, we reveal that the structure of the resulting hydrogen-bond chains depends on the isomeric composition of the molecules. If all molecules are homochiral (i.e., with only one isomer being present), they form secondary structures (chains of hydrogen bonds in the shapes of arcs, circles, and spirals). If the molecules at the substrate form a racemic mixture, then no regular secondary structures appear, and only curvilinear chains of hydrogen bonds of random shapes emerge. A hydrogen-bond chain can form a zigzag array only if it has an alternation of isomers. Such chains can create two-dimensional (2D) regular lattices or 2D crystals. The melting scenarios of such 2D crystals depend on density of its coverage of the substrate. At 25% coverage, melting occurs continuously in the temperature interval 295–365 K. For a complete coverage, melting occurs at 415–470 K due to a shift of 11% of all molecules into the second layer of the substrate. [ABSTRACT FROM AUTHOR]

Body-centered-cubic–face-centered-cubic (bcc–fcc) multi-metallic nanoparticles (NPs) associating a single-crystal core (Fe, FeCo alloys, etc.) with a polycrystalline noble metal shell (Au, AuAg alloys, etc.) are perfectly symmetrical or more irregular, even dramatically dissymmetrical, yet presenting a good crystalline organization. Here, a combination of experimental analysis and theoretical symmetry analysis is proposed, in order to provide a unified description of the observed morphologies (Fe–Au and Fe–AuAg systems), whatever their symmetry, and predict some morphology variability in a population of NPs. First, the central role of the crystal lattice accommodation is comprehensively analyzed from the experimental Fe–AuAg system. The two possible bcc–fcc epitaxial relationships generate a core–shell interface in the shape of a truncated rhombic dodecahedron. This results in two different types of grains in the shell, which are elastically accommodated between them by an equal distribution of twins and low-angle grain boundaries, however, at the cost of internal stresses. At the same time, symmetry breaking results from two possible growth variants originating from the Nishiyama–Wasserman epitaxial relationships. The shell grains fit together in a nanopuzzle-like organization, resulting in a large number of possible arrangements distributed in 13 different point groups of symmetry, all of lower order than the core symmetry (highest order of cubic symmetry). If the variants are randomly distributed, the probability for the NP to be asymmetric (group 1) is 80%. The dissymmetrical development of the NPs is then discussed. Extending this approach to other core shapes succeeds in predicting dissymmetrical or dramatically off-centered morphologies experimentally observed in Fe–Au NPs. [ABSTRACT FROM AUTHOR]

By electric transport measurements on high-purity bulk molybdenum single crystals at helium-temperature, it is shown that when approaching the ideal metallic crystal structure, there are deviations from Ohm's law that can exceed 30% even at low current densities ≅ 3 A / m m 2. This is due to the intrinsic circular magnetic field of the measuring current in the range of B ≅ 1 mT , which generates a magnetoresistance according to the two-band conduction model. With increasing lattice vibrations and/or crystal defects, this inherent uncertainty finally reduces to immeasurably small values. Finally, Ohm's law for a nearly ideal lattice structure can be strictly exact only in the theoretical limiting case of an infinite lattice plane, because then the magnetic fields of all electrons of the current compensate to zero. [ABSTRACT FROM AUTHOR]

The location of the H atoms in Ti, Zr, and Hf is crucial to the formation of the hydrides in these metals as it influences the crystal lattice transformation and the hydrogen diffusion involved in the hydride formation process. Although Ti, Zr, and Hf are all of hexagonal close-packed structure with similar lattice parameters, the solute H atom occupies the octahedral interstice in Ti but the tetragonal interstice in Zr and Hf, of which the origin is still mysterious. In the present work, the origin of the distinct site occupation behavior of H atom in Ti and Zr/Hf is investigated through first principles calculations. The calculated solution energies confirm that H prefers the octahedral interstice in Ti but the tetrahedral interstice in Zr and Hf. We ascribe the distinct site occupations of H in Ti and Zr/Hf to the varying Coulomb repulsion between the H (as a screened proton in the metals) and the matrix atoms against the interstitial size. The competition between the H-induced electron accumulation effect and the matrix atom debonding effect might matter as well. We propose that, as a general rule, a H atom prefers the site with a trade-off between a large space and a high electron density in metals. • Hydrogen occupies octahedral interstice in Ti but tetrahedral interstice in Zr/Hf. • H-metal atom Coulomb repulsion is responsible for the distinct site occupation of H. • H-induced electron redistribution might matter to the distinct site occupation of H. • H prefers the site with a trade-off between large space and high electron density. [ABSTRACT FROM AUTHOR]

Two T–X binary phase diagrams have been constructed between salicylic acid (SA) and two monotropic polymorphs of the isomer 3-hydroxybenzoic acid (3HBA). Crystalline solid solutions (CSS) were formed at all extremes of the phase diagrams. The solid-state miscibilities ranged from 0.5% up to 6% of the second component. The thermodynamically stable form I of 3HBA exhibited a higher solid state miscibility than form II of 3HBA across all investigated temperatures. The solubility changes induced by the different CSS were measured experimentally in 40 w% methanol in water at 25 °C and are presented in two ternary phase diagrams. The SA-rich CSS phase exhibited the highest solubility increase corresponding to 160% up to the solvus at 0.7% 3HBA in SA. The changes in solubility of the CSS phases belonging to the two 3HBA polymorphs were found to diverge with increasing incorporation of SA in the respective crystal lattices. This thermodynamic divergence in combination with the monotropic stability relationship caused the driving force for polymorphic conversion to increase with increasing SA content. This unusual scenario was demonstrated experimentally through the use of solution-mediated phase transformation (SMPT) experiments analyzed in situ by Raman. It was found that the incorporation of 0.5% SA in the crystal lattice of 3HBA form II caused the polymorphic conversion rate to form I to double, in comparison to when 3HBA is chemically pure. The current example thus demonstrates the thermodynamic context for how solid-state miscible impurities can expedite polymorphic conversions. This and other contributions showcase how the rates of crystallization can be enhanced or reduced solely based on formation of CSS with an impurity or additive, without accounting for any surface adsorption effects. [ABSTRACT FROM AUTHOR]

Traditional studies on boride cermet have rarely considered the effects of the synergistic interactions among their multiple components on their microstructure and properties. In this study, FeCrNiCo-boride cermet is prepared for the first time via hot-press sintering. The microstructure evolution and corrosion resistance of the cermet are investigated for sintering temperatures in the range of 1000–1300 °C. The results show that the phase comprises Mo 2 FeB 2 , MoB 2 , and FCC phases (including that of FeCrNiCo or various intermetallic solid solutions formed by FeCrNiCo decomposition). Owing to its low Gibbs free energy, Mo 2 FeB 2 occurs in the hard phase. Cr atoms dissolve into the crystal lattice and stabilise the Mo 2 FeB 2 crystals. A certain amount of MoB 2 is also present in the hard phase. The bond phase is formed by alloying elements and solid solutions. The cermet sintered at 1100 °C exhibits the least structural defects, highest cermet content, and best corrosion resistance; the porosity is 9.94 % and phase ratio of cermet is 48.9 %. The cermet phase has the smallest grain size of 5.96 μm. The equilibrium potential (E corr) is −0.52 V, corrosion current density (I corr) is 2.07 × 10−6 A/cm2, and open-circuit potential (OCP) in a 3.5 % NaCl solution is −0.34 V. [ABSTRACT FROM AUTHOR]

In this paper we studied the possibility of synthesizing solid solutions based on barium hexaferrite, iron atoms Fe3+ in which are partially substituted by Cr3+ atoms, and their magnetic properties. Thirteen solid solutions of BaFe 12-x Cr x O 19 compositions with varying degrees of chromium substitution x (Cr) = 0–6 with a step of x (Cr) = 0.5 were obtained using the solid-phase synthesis method. X-ray phase analysis showed that at a temperature of T = 1400 °C, solid solutions with a single crystalline phase corresponding to the structure of magnetoplumbite were formed within 5 h. As a result of chromium Cr3+substitution for iron Fe3+, a monotonous decrease in the parameters of the crystal lattice occurred. We studied the temperature and frequency dependences of the initial magnetic permeability of the resulting ferrites. It was revealed that substitution of iron by chromium led to a decrease in the Curie temperature. All the studied compositions had a feature in the form of a narrow peak near the Curie temperature. We suggested that this feature appeared as a result of a change in the domain structure. Analysis of the temperature dependences allowed us to conclude that Cr3+ substituted for iron in all crystallographic positions with equal probability. It was shown that the initial permeability of ferrites decreased with increasing frequency. [Display omitted] [ABSTRACT FROM AUTHOR]

By combining structural design with heteroatom doping, Mn-doped CuS 3D hollow flower spheres are designed, which are encapsulated in nitrogen and sulfur co-doped carbon (M/CuS-NSC). M/CuS-NSC collaboratively enhances the electrode's stability and conductivity, thus enabling it to exhibit a residual capacity of 511.5 mAh g−1 after 10,000 cycles at 10 A g−1, with an average decay rate of 0.00009%. [Display omitted] • The doped Mn atoms make it easier for Na+ insertion/extraction by enlarging Cu crystal lattice. • Carbon with co-doped S, N atoms could form a large subsurface via the C S C bond, and enrich active sites. • The designed structure could effectively alleviate volume expansion and constructs an effective 3D charge transfer network through nanosheets. • It is innovative found that the copper current collector has different activation effects on sodium storage with different active materials. To achieve both the capacity and stability of metal sulfides simultaneously remains a significant challenge. In this study, we have synthesized the manganese-doped copper sulfide three-dimensional (3D) hollow flower-like sphere (M/CuS-NSC), encapsulated in a nitrogen and sulfur co-doped carbon. The hollow lamellae structure allows the rational self-aggregation process of numerous active surface area enlarged nanosheets, thereby enhancing electrochemical activity. The subsurface framework characterized by C S C bonds enhances the pseudo-capacitive properties. Furthermore, the transformation of sulfur and the isomerization of carbon contribute to the enhancement of sodium ion storage. The incorporation of Mn into CuS lattice increases the interplanar distance, providing additional space for the accommodation of sodium ions. Mn doping facilitates the localization of electrons near the Fermi level, thereby improving conductivity. Additionally, Cu foils coated with M/CuS-NSC-2 engage with the electrolyte and sulfur, initiating the reaction sequence through the formation of Cu 9 S 8. Consequently, M/CuS-NSC-2 exhibits highly reversible capacities of 676.24 mAh g−1 after 100 cycles at 0.1 A g−1 and 511.52 mAh g−1 after 10000 cycles at 10 A g−1, with an average attenuation ratio of only 0.009 %. In this study, we propose an effective strategy that combines structural design with heteroatom doping, providing a novel approach to enhance the electrochemical performance of monometallic sulfide. [ABSTRACT FROM AUTHOR]

The electrochemical production of hydrogen peroxide through the oxygen reduction reaction (ORR) presents the interesting situation where the fully reduced form, H2O, is significantly favored by thermodynamics. Perovskite oxide based catalysts with slow kinetics, or large overpotentials, have been shown to enable production of H2O2 with good selectivity, but this comes at the expense of energy efficiency and production rates. We analyze the structure and electrocatalytic ORR capabilities of a perovskite oxide series based on LaCr1‐xCoxO3. We find that the crystal lattice distorts in two ways as Co content increases – anisotropic compression of the lattice is accompanied by a pinching of angles within the structure, which gives way to compression of B−O bonds at higher Co contents. Product selectivity is observed to change as a function of both catalyst composition and rotation rates of rotating ring‐disk electrode. The rotation‐dependent behavior is attributed to accelerated displacement of surface‐bound peroxide intermediates by a pH gradient at the catalyst surface, and composition‐dependent changes in selectivity are found to correlate to the angular distortion of the crystal lattice. These results highlight the importance of local environments in electrocatalyst reactions and demonstrate that structure and local pH can be used to manipulate product selectivity. [ABSTRACT FROM AUTHOR]

Vacancies in solid-state physics are underexplored in materials with strong electron-electron correlations. Recent research on the Ir-Sb binary system revealed an extended buckled-honeycomb vacancy (BHV) order. Superconductivity arises by suppressing BHV ordering through high-pressure growth with excess Ir atoms or Rh substitution, yet the superconducting pairing nature remains unknown. To explore this, we conducted muon spin rotation experiments on Ir1−δSb (synthesized at 5.5 GPa, Tc = 4.2 K) and ambient pressure synthesized optimally Rh-doped Ir1−xRhxSb (x=0.3, Tc = 2.7 K). The exponential temperature dependence of the superfluid density suggests a fully gapped superconducting state exists in both samples. The ratio of Tc to the superfluid density resembles that of unconventional superconductors. A significant increase in the superfluid density in the high-pressure synthesized sample correlates with Tc, indicating that unconventional superconductivity is intrinsic to the Ir-Sb binary system. These findings, along with the dome-shaped phase diagram, highlight IrSb as the first unconventional superconducting parent phase with ordered vacancies, requiring further theoretical investigations. Vacancies or defects are structural features of the crystal lattice that can be used to engineer the physical properties of a solid-state system, and have played an important role in the investigation of quantum materials. Here, the authors apply muon spin rotation to explore the suppression of vacancy ordering in Rh-doped Ir1−xRhxSb and discuss the potential presence of unconventional superconductivity in the system. [ABSTRACT FROM AUTHOR]

Perovskite solar cells have become a leading contender in next‐generation photovoltaic technologies due to their high efficiency and low‐cost potential. Managing the deep defects present effectively in the crystal lattice and at the interfaces is essential for enhancing the performance and longevity of perovskite solar cells. Here, perovskite's crystallization modulation and interfacial defect passivation are achieved by developing a guanidinium iodide (GAI)‐based surface passivation strategy. The integration of GAI passivates the grain boundaries, leading to a perovskite thin film with a smoother and more uniform grain distribution, facilitating charge carrier transport. Notably, the ammonium group, unsaturated nitrogen atoms, and iodide ions in GAI can collectively repair the surface defects of perovskite through various pathways, effectively suppressing non‐radiative recombination, thereby enhancing the photovoltaic performance of the device. Ultimately, the champion device treated with GAI achieves a power conversion efficiency (PCE) of 23.02% and demonstrates similar ambient stability under unencapsulated conditions. These findings underscore the effectiveness of GAI passivation as a strategy to balance the improvement of the performance and stability of perovskite solar cells. [ABSTRACT FROM AUTHOR]

In this study, the element substitution technique was utilized to create a solid solution, which in turn allowed for the manipulation of lattice parameters. The microwave dielectric properties of Mg 1.8 R 0.2 Al 4 Si 5 O 18 (R=Mg, Ni, Zn, Cu, Sr, Ca, Ba) ceramics were investigated following the substitution of Mg2+ ions. The influence of microstructural alterations on these properties was also examined. A cordierite solid solution was formed when R = Ni, Cu, Sr, or Ba; however, an additional phase emerged when R = Zn, Sr, or Ca. The complete substitution influenced the relative dielectric constant of Mg 1.8 R 0.2 Al 4 Si 5 O 18 due to the ionic polarizability and the average ionic property of the R ion. The Q × f value was found to be related to the crystal lattice energy, while the τ f value was primarily affected by octahedral distortion. The appearance of a secondary phase altered the primary factors influencing the dielectric properties of the Mg 1.8 R 0.2 Al 4 Si 5 O 18 ceramics. Among the substitutions tested, Mg 1.8 Ni 0.2 Al 4 Si 5 O 18 exhibited superior microwave dielectric properties with ε r = 4.64, Q × f = 44,770 GHz, and τ f = −32 ppm/°C. [ABSTRACT FROM AUTHOR]

Defect passivation inside the crystal lattice and the grain‐boundary (GB) surface of the perovskite films has become the most effective strategy to suppress the negative impact of the nonradiative recombination in perovskite solar cell. In this study, a unique approach to effectively passivate the defect states of MAPbI3 perovskite thin film using thionicotinamide (TNM) as a multifunctional Lewis base additive is demonstrated. TNM as an additive with three different types of Lewis base sites, i.e., pyridine, amino, and CS functional groups, is introduced to mitigate the trap states in the TNM‐modified perovskite films and thoroughly investigate the passivation defects. The nonbonded electron of the three different Lewis base sites can synergistically passivate the antisite lead (Pb) defects and improve the stability of the device. In addition, the NH2 group can form ionic bonds with negatively charged I– ions and inhibit ion migration caused by them. It is found that such passivation effect of TNM reduces the GB defects and improves the crystallinity significantly. As a result, a champion TNM‐modified device shows an improved power conversion efficiency of 19.26% from 16.86% along with enhanced open‐circuit voltage, fill factor, and negligible hysteresis. [ABSTRACT FROM AUTHOR]

Graphene quantum dots (GQDs), small graphene domains with lateral dimensions lower than 10 nm, are increasingly used in electronics, composites, and biomedicine. Chemical doping of GQDs allows tuning their optical properties. Immune cells are among the first cells exposed to nanomaterials entering a living body, rapidly triggering a downstream immune response. However, the assessment of the impact of chemically‐doped GQDs on the immune system remains rather limited if not absent. In this context, the effects and the biodegradability of sulfur‐doped and nitrogen‐doped GQDs (S‐GQDs and N‐GQDs) on human monocytes and macrophages are evaluated. The metabolic activity, membrane integrity, apoptosis, and intracellular reactive oxygen species (ROS) generation are studied. In parallel, the degradation of GQDs using human myeloperoxidase and a peroxynitrite‐mediated system is investigated in test tube. Their degradation in macrophages is also pursued. High‐resolution transmission electron microscopy (HRTEM), fluorescence spectroscopy, Raman, and flow cytometry are used to confirm the degradation. Overall, both GQDs exert little activation on monocytes and macrophages although they decrease the metabolic viability in a dose‐dependent manner. The loss of native GQD structure and crystal lattice provide evidence of their biodegradability. Both the safety and biodegradability of S‐GQDs and N‐GQDs ensure their potential in biomedical applications. [ABSTRACT FROM AUTHOR]

This work is devoted to studying and manufacturing a highly sensitive nonenzymatic glucose biosensing system of metal oxides via the sol–gel technique. The X‐ray diffraction patterns of all the prepared samples confirm that the samples present hexagonal crystal lattice structures of ZnO and Ag–ZnO nanoparticles. Ultraviolet (UV) analysis of all the samples is carried out to evaluate the absorption of silver in the UV region for electrical and chronoamperometric analysis. The transmittance of all the samples is observed, and the maximum transmittance is 11% for 4% AgZnO. Fourier transform infrared spectroscopy reveal the functional group stretching and vibration of the particles at different wavelength ranges. Scanning electron microsocpy analysis reveals the grain size and morphology of the samples, which decrease with increasing doping agent. Chronoamperometric analysis of all the samples reveals that the value increases with time for the 4% doped sample. The sensing response is also observed and is enhanced with increasing temperature for the 4% doped sample. The sensing response of the samples coated with carbon fiber electrodes is assessed from −0.2 to +0.5 V at a scan rate of 50 mV s−1. [ABSTRACT FROM AUTHOR]

Many proton-conducting oxides are refractory, making it difficult to fabricate dense electrolyte membranes for electrochemical devices. The use of a sintering additive is a common strategy, although it often has a negative effect on proton transport. We found that the addition of ZnO (2 and 4 mol%) successfully contributes to densification of SrHf 0.8 Sc 0.2 O 3-δ ceramics at 1450 °C without negative consequences for the ionic transport. The chemical stability of the materials, high levels of hydration and proton conductivity were confirmed. ZnO is partially (less than 0.3 mol%) incorporated into the crystal lattice of the perovskite and partially accumulates at grain boundaries gradually volatilizing during high-temperature treatments. As a result, ZnO sintering additive does not influence the bulk and specific grain-boundary conductivities, ionic transference numbers and hydration ability, maintaining the excellent electrolytic properties of SrHf 0.8 Sc 0.2 O 3-δ ceramics. [ABSTRACT FROM AUTHOR]

Nine different derivatives of piperidino alanes of the general formula (CH2)5N‐AlXY [X=Y=Cl (1), Br (2), I (3); X=(CH2)5N, Y=Cl (4), Br (5), I (6); X=H, Y=Cl (7), Br (8), I (9)] have been synthesized and compared with respect to their structures. All molecules form dimers with an Al2N2 central cycle and aluminum and nitrogen atoms in distorted tetrahedral environments as determined from X‐ray diffraction. The three dihalide derivatives 1, 2 and 3 have C2h (2/m) symmetries in solution of which they maintain the Centro symmetry in the crystal lattice. The bis(piperidino) derivatives 4, 5 and 6 have either C1 (1) symmetry with the bridging piperidino cycles oriented in the same direction (4, 5) or Ci (ī) point symmetry as found for 6 (in solution at least one other isomer is present). Whereas the chlorine derivative 7 has crystallographic Ci (ī) symmetry, the bromine 8 has almost C2 and the iodine 9 crystallographic C2 (2) point symmetry. In solution all derivatives 7, 8, 9 show equilibria between cis (C2) and trans (Ci) isomeric forms (27Al NMR). The longest Al−N bond lengths within the rings are found for 5 (1.969(4) Å) and the shortest for 8 (1.940(4) Å). The ratio of Al⋅⋅⋅Al to N⋅⋅⋅N non‐bonding distances in the almost square rings vary with the bulkiness of the terminal ligands at aluminum. [ABSTRACT FROM AUTHOR]

In this report, rare-earth-free Mg4Nb2O9:Mn4+ phosphors were obtained through a high-temperature solid-state reaction. This work aims to investigate the photoluminescence properties of Mg4Nb2O9:Mn4+ phosphors and the temperature sensitive performance of the optimized phosphor. The crystal structure and lattice parameters as well as the effects of the dopant ions on the host structure were investigated. It should be noted that the Mg4Nb2O9 crystal is in a trigonal system P3¯c1. The as-prepared phosphors exhibited good thermal sensitivity, and the relative sensitivity of the optimal Mg4Nb2O9:0.004Mn4+ phosphor was calculated to be 0.48% K−1, allowing it to activate optical temperature sensing applications. [ABSTRACT FROM AUTHOR]

Achieving precise and controllable hierarchical self-assembly of functional nanoclusters within crystal lattices to create distinct architectures is of immense significance, yet it creates considerable challenges. Here we successfully synthesized a silver nanowheel Ag40, along with its optically pure enantiomers S-/R-Ag40. Each species possesses an internal nanospace and exhibits host-guest interactions. These structures are constructed from primary building blocks (Ag9). By manipulating the surface anions and guest molecules, the nanowheels function as secondary building blocks, spontaneously organizing into complex double- and triple-helical crystalline superstructures or one-dimensional chains {Ag41}n through conformational matching and diverse noncovalent interactions. Moreover, we demonstrate that the water-mediated complex specifically assembled with uridine monophosphate nucleotides, resulting in chiral assemblies of Ag40 that exhibit chiroptical activity for specific recognition. Our findings provide insights into the efficient construction of assemblies with hollow frameworks and propose strategies for superstructure engineering by manipulating surface motifs. Achieving precise and controllable hierarchical self-assembly of nanoclusters within crystal lattices is of immense significance yet remains challenging. Here the authors synthesize a silver nanowheel Ag40, along with its optically pure enantiomers S-/R-Ag40, and characterize its self-assembly into double- and triple-helical superstructures. [ABSTRACT FROM AUTHOR]

The influence of Eu doping (0.5, 1 and 2 mol.%) and annealing in an oxygen-deficient atmosphere on the structure and optical properties of SnO2 nanoparticles were investigated in relation to electronic structure. The X-ray diffraction (XRD) patterns revealed single-phase tetragonal rutile structure for both synthesized and annealed Eu-doped SnO2 samples, except for the annealed sample with 2 mol.% Eu. The results of X-ray photoelectron spectroscopy (XPS) emphasized that europium incorporated into the SnO2 host lattice with an oxidation state of 3+, which was accompanied by the formation of oxygen vacancies under cation substitution of tetravalent Sn. Moreover, XPS spectra showed the O/Sn ratio, which has been reduced under annealing for creating additional oxygen vacancies. The pulse cathodoluminescence (PCL) demonstrated the concentration dependence of Eu site symmetry. Combination of XRD, XPS and PCL revealed that Eu doping and following annealing induce strongly disordering of the SnO2 crystal lattice. Our findings provide new insight into the interaction of rare-earth metals (Eu) with host SnO2 matrix and new evidence for the importance of oxygen vacancies for optical and electronic structure formation. [ABSTRACT FROM AUTHOR]

This study investigated changes in the crystal lattice, tribological properties and friction mechanism of AISI 316 steel irradiated with swift 160 MeV xenon ions. The irradiation process caused the increased roughness of the steel surface and the swelling of the material. The thickness of the irradiated layer increased by about 13 nm. Following irradiation with the fluences 2.5 × 1014 and 3.2 × 1014 (Xe24+/cm2), martensite formed in the surface layer. Fluctuating changes were also observed with respect to the coefficient of friction and the degree of wear of the AISI 316 steel samples. Irradiation also increased the microhardness of the steel. [ABSTRACT FROM AUTHOR]

Amorphous films are formed on substrates at room temperature in the process of anodic oxidation of niobium foil. The studies were carried out using methods of electron diffraction and "in situ" transmission electron microscopy (TEM) with video recording of structural changes. It was found that electron beam irradiation of the film with a dose rate (4–7)·104 e−/Å2·s inside the column of the electron microscope causes its layer polymorphous crystallization (LPC) with the formation of Nb2O5 crystals with hexagonal lattice. The dimensionless parameter of the relative crystallization length δ0≈ 5000 − 7000. The dependence on time of the crystal diameter is described by a power function with exponents of 1.55, 1.1 and 1.3. According to this the dependence of the fraction of the crystalline phase on time is described by a power function with exponents of 3.1, 2.2 and 2.6. This non-quadratic nature is explained with the formation of a domain superstructure in the low-temperature modification of α-Nb2O5 and phenomenon of polyamorphism in amorphous films. [ABSTRACT FROM AUTHOR]

Spin‐crossover (SCO) complexes have drawn significant attention for the possibility to photoswitch their electronic spin state on a sub‐picosecond timescale at the molecular level. However, the multi‐step mechanism of laser‐pulse‐induced switching in solid state is not yet fully understood. Here, time‐resolved synchrotron X‐ray diffraction is used to follow the dynamics of the crystal lattice in response to a picosecond laser excitation in nanometric thin films of the SCO complex [Fe(HB(1,2,4‐triazol‐1‐yl)3)2]. The observed structural dynamics unambiguously reveal a lattice expansion on the 100 picosecond timescale, which is temporally decoupled both from the ultrafast molecular photoswitching process (occurring within 100 fs) and from the delayed, thermo‐elastic (Arrhenius‐driven) conversion (taking place ≈10 ns). These time‐separated dynamics are also manifested by the observation of damped acoustic oscillations in the time evolution of the lattice volume, whereas no such oscillations are observed in the electronic spin‐state dynamics. Overall, these results suggest the existence of a universal behavior whereby the intramolecular energy barrier between low‐spin and high‐spin states acts as an intrinsic dynamical bottleneck in the out‐of‐equilibrium spin‐state switching dynamics of SCO materials. [ABSTRACT FROM AUTHOR]

Mg metal anode‐based battery is a more sustainable, lower cost, and higher energy density alternative to Li‐ion. However, this battery chemistry also faces several challenges associated with the high charge density of Mg2+, including achieving high reversibility and low voltage hysteresis for Mg metal plating/stripping. While significant improvements are achieved in last decades, they involve rather complex electrolyte formulations and/or Mg salts difficult to produce, and the use of unpractical substrates such as platinum. Here, significant improvement in terms of Mg plating kinetics is achieved in electrolytes containing commercial magnesium bis(trifluoromethanesulfonyl)imide salt (Mg(TFSI)2) by using titanium substrate with similar crystal structure and lattice parameter as Mg leading to lower nucleation overpotential. Low salt concentration electrolyte and addition of dibutyl magnesium (Mg(butyl)2) also enable the formation of thinner interphase, richer in solvent based decomposition products, further improving Mg plating kinetics. This work highlights the complex role of Mg(butyl)2, often considered as a simple drying agent, and how it impacts ion solvation favoring the mobility of electroactive cationic species, paving the way toward better electrolyte design with improved cation transference number. [ABSTRACT FROM AUTHOR]

A narrow-band green emitting K3Tb(PO4)2 phosphor has been synthesized by a novel single-crystal growth approach involving the application of an inert flux. Its structural and spectroscopic peculiarities have been systematically studied by means of single-crystal X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray spectroscopy analysis, and diffuse reflectance, infrared and photoluminescence spectroscopy. The layered framework of the title compound is organized by linking together slightly distorted phosphate tetrahedra with non-condensed TbO7 polyhedra into [Tb(PO4)2]3− sheets interconnected by potassium cations. K3Tb(PO4)2 reveals an intense slow green photoluminescence (PL) (decay time constant τ is near 2.6 ms) under excitation in the range from VUV (100 nm) up to blue light (484 nm). Intensive narrow lines of the 5D4 → 7F6-0 (4f8 → 4f8) radiative transitions in Tb3+ ions form the PL spectra. Besides, fast violet PL (time constant τ < 20 ns) occurs under PL excitations in a narrow range from 250 to 325 nm. Dependencies of the PL quantum yield, and the green and violet PL decays on the excitation wavelength have been analyzed taking into account the multi-phonons, cross-relaxation processes and exciting light absorption by the inherent defects in the K3Tb(PO4)2 crystal lattice. The dependency of the complex characteristics of PL quantum yield on the excitation wavelength and violet photoluminescence is ascribed to the formation of Tb4+ ions. The color coordinates and color purity of the emission were estimated for the cases of PL excitation in the 160–371 nm spectral range. It has been shown that these characteristics are similar to or even better than those reported for conventional commercial green phosphors. The high values of correlated color temperature (T > 4863 K) of the emission indicates the potential use of K3Tb(PO4)2 for enhancing cold-light emitting devices. [ABSTRACT FROM AUTHOR]

Exploring the organic molecular structural features and supramolecular interactions provide basis for developing stimuli-responsive organic solid-state fluorescent materials. Herein, we have synthesized methoxyphenyl-substituted carbazole-based π-conjugated derivatives (Cz-MN, Cz-ECA, Cz-CA, Cz-CAA and Cz-NBA) with different acceptor units and investigated their influence on solid-state fluorescence. All five compounds showed aggregation-induced emission (AIE) in the solid state with acceptor-dependent tunable fluorescence from 488 to 602 nm (quantum yield (Φf) = 7.2 to 1.9%). Cz-ECA exhibited blue-shifted fluorescence, whereas Cz-NBA showed red-shifted fluorescence. Cz-MN, Cz-ECA and Cz-CA revealed relatively strong solid-state fluorescence compared to Cz-CAA and Cz-NBA. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) calculations suggested intramolecular charge transfer (ICT) from the carbazole donor to the acceptor unit. Mechanofluorochromic studies of Cz-MN and Cz-ECA showed self-reversible fluorescence switching but the other three AIEgens did not show any stimuli–response. Single crystal structural analysis of Cz-MN, Cz-ECA and Cz-CA showed twisted molecular conformations with different intermolecular interactions. Both Cz-MN and Cz-ECA did not show any strong intermolecular interactions in the crystal lattice. In contrast, Cz-CA exhibited strong amide–amide complementary H-bonding and an extended network structure. Hence, the twisted molecular conformation and the absence of strong intermolecular interactions in Cz-MN and Cz-ECA contributed to self-reversible mechanofluorochromism (MFC). Thus, the present study is expected to provide further insight to design AIEgens with stimuli-responsive self-reversible fluorescent materials. [ABSTRACT FROM AUTHOR]

Background: Sacubitril/valsartan, marketed as Azmarda (manufactured by the innovator company) is a cocrystal consisting 6 sacubitril and valsartan molecules, along with sodium cations and water molecules. This formulation is considered a major mechanism of benefit of this molecule. This study was aimed to assess various brands of sacubitril/valsartan in the market for the presence of the cocrystal forms and compare them with Azmarda. a brand of sacubitril/valsartan manufactured by the innovator company. Methods: The study involved analysis of various marketed products containing sacubitril/valsartan tablets, including Azmarda. Both the Azmarda and marketed products were characterized using differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD). Sodium content and dissolution studies were also performed . Results: A total of 16 brands of marketed products including Azmarda were studied. During DSC studies, unique melting pattern was observed in Azmarda, with exothermic peaks of sacubitril/valsartan detected at 140°C and 102°C, respectively. PXRD analysis revealed that none of the products exhibited the same crystal lattice as Azmarda. Azmarda, with a sodium level of 1.773%, was comparable to brand 2 (1.61%), brand 4 (1.73%), and brand 7 (1.58%). Azmarda demonstrated 64% release of sacubitril and 57% release of valsartan within 30 minutes in 0.1N HCl. Brand 7, brand 12, and brand 13 showed 52%, 57%, and 52% release of sacubitril, respectively, and 45%, 52%, and 48% release of valsartan, respectively, in 30 minutes. Conclusion: The absence of identical crystal lattice structures, highlights absence of cocrystalsin generic formulations. Such variations may impact the bioavailability and efficacy, emphasizing the importance of ensuring consistent and reliable therapeutic outcomes. [ABSTRACT FROM AUTHOR]

We begin by deriving the nonlinear Schrödinger equation (NLSE) in the presence of nonlinear microstructures, where the refractive index undergoes periodic modulation in the transverse direction for photonic crystal containing circular shape. Our investigation delves deeply into the intricate mechanisms behind transverse and longitudinal modulation of the refractive indexes, which aligns with the design of numerous manufactured slab microstructure waveguides. Theory of solitary waves in nonlinear microstructure, here unconventional fiber has been studied and examined in detail. In this work, composite methods leading both transverse and longitudinal modulation of refractive indexes have been presented in detail. The work also presents the diverse characteristics of this NLSE for both homogeneous and nonhomogeneous medium, encompassing various orders of nonlinearity specific to the nonlinear microstructure under consideration. Additionally, we analyze the wave propagation profiles for wide signals, which are wider than the periodicity of micro-structured photonic crystal. We also conduct a perturbation analysis for narrow signals that are even narrower than the periodicity of photonic crystal in transverse direction. [ABSTRACT FROM AUTHOR]

This study investigates the impact of kaolin and boehmite alumina binders on the synthesis, catalytic properties, and attrition resistance of a La0.7Sr0.3FeO3 (LSF) perovskite catalyst designed for the chemical looping partial oxidation (CLPO) of methane to produce synthesis gas sustainably. The as-synthesized and used catalysts with varying kaolin and boehmite alumina contents (KB(x,y)/LSF) were scrutinized by a variety of characterization methods, including XRD, FE-SEM/EDS, BET, TPD-NH3, and TPD-O2 techniques. The catalytic activity of the synthesized samples was tested at 800 to 900 °C in a fixed-bed reactor producing syngas through the CLPO process over the consecutive redox cycles. Additionally, the attrition resistance of the fresh and used catalyst samples was examined in a jet cup apparatus to assess their durability against the stresses induced by thermal shocks or changes in the crystal lattice caused by chemical reactions. The characterization results showed the pure perovskite crystal structure of KB(x,y)/LSF catalysts demonstrating adequate oxygen adsorption capacity, effective coke mitigation capability, robust thermal stability, and resilience to agglomeration during repetitive redox cycles. Among the tested catalysts, KB(25,15)/LSF was identified as the superior sample, as it could consistently produce syngas with a suitable H2:CO molar ratio varying from 2 to 3 within ten redox cycles at 900 °C, with CH4 conversion and CO selectivity values up to 64% and 87%, respectively. The synthesized catalysts demonstrated a logarithmic attrition pattern in the jet cup tests at room temperature, featuring high attrition resistance after the erosion of particle shape irregularities or weakly bound particles. Moreover, the KB(25,15)/LSF catalyst used at 900 °C showed great resistance in the attrition test, warranting its endurance in the face of extraordinarily harsh conditions in fluidized bed reactors employed for the CLPO process. [ABSTRACT FROM AUTHOR]

Quaternion and biquaternion symmetry transformations have been applied to non-Cartesian reference systems of direct and reciprocal crystal lattices. The transformations performed directly in the sets of crystal reference axes simplify the calculations, eliminate the need for orthogonalization, permit the use of crystallographic vectors for defining the directions of rotations and perform the computations directly in the crystal coordinates. The applications of the general quaternion transformations are envisioned for physical, chemical, crystallographic and engineering applications. The general quaternion multiplication rules for any symmetry-unrestricted lattices have been derived for the triclinic crystallographic system and have been applied to the biquaternion representations of all point-group symmetry elements, including the crystallographic hexagonal system. Cayley multiplication matrices for point-groups, based on the biquaternion symbols of proper and improper symmetry elements, have been exemplified. [ABSTRACT FROM AUTHOR]

Previous studies have demonstrated that the surface curvature of cylindrical magnetic nonawires can induce fascinating dynamic magnetization properties. It was recently proposed that ferromagnetic nanotubes can be utilized as skyrmion guides, enabling the avoidance of the annihilation of skyrmions in the lateral boundaries as in flat thin-film strips. In this work, we demonstrate via micromagnetic simulation that multiple skyrmions can be stabilized in a cross-section of a ferromagnetic nanotube with interfacial Dzyaloshinskii–Moriya interaction (iDMI). When uniformly arranged, these skyrmions together can perform as a crystal lattice for spin waves (SWs) propagating in the nanotube. Our simulations show that the skyrmion lattice can contribute a chiral effect to the SW passing through, namely a circular polarization of the SW. The handedness of the polarization is found to be determined by the polarity of the skyrmions. A physical explanation of the observed effect is provided based on the exchange of angular momentum between SWs and skyrmions during the scattering process. Our results display more possibilities to exploit magnetic nanotubes as SW and skyrmion guide in the development of novel spintronic devices. [ABSTRACT FROM AUTHOR]

Context: Ammonium Tutton salts have been widely studied in recent years due to their thermostructural properties, which make them promising compounds for application in thermochemical energy storage devices. In this work, a detailed experimental study of the Tutton salt with the formula (NH4)2Zn(SO4)2(H2O)6 is carried out. Its structural, vibrational, and thermal properties are analyzed and discussed. Powder X-ray diffraction (PXRD) studies confirm that the compound crystallizes in a structure of a Tutton salt, with monoclinic symmetry and P21/a space group. The Hirshfeld surface analysis results indicate that the main contacts stabilizing the material crystal lattice are H···O/O···H, H···H, and O···O. In addition, a typical behavior of an insulating material is confirmed based on the electronic bandgap calculated from the band structure and experimental absorption coefficient. The Raman and infrared spectra calculated using DFT are in a good agreement with the respective experimental spectroscopic results. Thermal analysis in the range from 300 to 773 K reveals one exothermic and several endothermic events that are investigated using PXRD measurements as a function of temperature. With increasing temperature, two new structural phases are identified, one of which is resolved using the Le Bail method. Our findings suggest that the salt (NH4)2Zn(SO4)2(H2O)6 is a promising thermochemical material suitable for the development of heat storage systems, due to its low dehydration temperature (≈ 330 K), high enthalpy of dehydration (122.43 kJ/mol of H2O), and hydration after 24 h. Methods: Computational studies using Hirshfeld surfaces and void analysis are conducted to identify and quantify the intermolecular contacts occurring in the crystal structure. Furthermore, geometry optimization calculations are performed based on density functional theory (DFT) using the PBE functional and norm-conserving pseudopotentials implemented in the Cambridge Serial Total Energy Package (CASTEP). The primitive unit cell optimization was conducted using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm. The electronic properties of band structure and density of states, and vibrational modes of the optimized crystal lattice are calculated and analyzed. [ABSTRACT FROM AUTHOR]

The features of the infrared (IR) spectra of various isotopic forms of water (–OH, –OD, H2O, HDO, and D2O) included in the crystal structure of the main rock-forming minerals of lunar basalts—olivines (forsterite)—have been studied. The results of numerical modeling (CUSTEP/Biovia Materials Studio) and experimental studies using the FT-801 IR Fourier spectrometer with a plug-in using the method of disturbed internal reflection (Simex, Novosibirsk) are presented. Numerical calculations have shown that forsterite can contain hydroxyl groups –OH(D) in its crystal lattice under certain conditions. The possibility of retaining various isotopic forms of molecular water on the surface of forsterite has been experimentally verified and the corresponding IR spectra of the mineral with a water film have been obtained. The IR spectra of forsterite containing isotopologues of water obtained theoretically and experimentally are compared with the observations of the Chandrayaan-1 and SOFIA artificial lunar satellites. [ABSTRACT FROM AUTHOR]

Antimony-Selenium-Tin (Sb-Se-Sn) is a ternary chalcogenide have wide range of potential applications, because of their high strength, various crystal lattices, and electrical characteristics. In this work, the melt quenching method was used to synthesize the nanoparticles of Sb14Se86-xSnx (x = 0, 3, 6, 9, 12) chalcogenide glasses. X-ray diffraction (XRD) and the Scanning electron microscopy (SEM) of the Sb14Se74Sn12 chalcogenide glasses ascertained the amorphous characteristics. No extra impurity was detected in any chalcogenide, and the presence of only Sb, Se and Sn was detected from the EDS spectra. The decrease in band gap is revealed with the increase of Sn content in the Sb14Se86-xSnx glasses. Lowest band gap was observed in the Sb14Se74Sn12 chalcogenide, attributed to the large crystallite size. The FTIR spectrum of the sample reveals an absorption band roughly between 500 –400 cm-1, attributed to the vibrational modes for Sb–Se, Sn–Se and Sn-Sb bonds. In the chalcogenide glasses, the Sn and Sb 3d state comprises of two peaks, corresponding to doublet state (3d5/2 and 3d3/2), while as Se has only singlet state (3d). In conclusion, in the Sb14Se86-xSnx (x = 12) chalcogenide glass, an increase in photoluminescence intensity and the decrease in band gap makes it potential candiate for the infrared detectors, and the infrared optical fibres. [ABSTRACT FROM AUTHOR]

In this paper, 4. 2% ytterbium-doped calcium niobium gallium garnet (Yb∶Ca3 (NbGa)5 O12) crystals with diameter of 2 inch (1 inch =2. 54 cm) were grown by Bridgman method. The obtained crystals were intact and free of visible defects. Crystal structure was determine by XRD, which reveals that the crystal belongs to the cubic crystal system with lattice parameters a = b = c =12. 493 Å. The crystals were oriented and cut to obtain some (420) plane wafers with dimensions of 10 mm ×10 mm ×1 mm. These wafers were double-side polished to obtain the final samples. The performance of the samples was characterized through X-ray diffraction, ultraviolet-visible spectrophotometer, and fluorescence spectroscope. The results show that the rocking curve of the crystal has a full width at half maximum (FWHM) of 43″, and the transmittance reaches 80% in the near-infrared wavelength range. At 935 nm, FWHM of the absorption peak is 47. 15 nm and absorption crosssection is 1. 53 ×10 -20 cm2. When excited with a 980 nm laser, an emission peak was observed at 1 031 nm, corresponding to the transition of Yb3 + from the excited state 2 F5/2 to the ground state 2 F7/2. [ABSTRACT FROM AUTHOR]

Chiral perovskites are considered as promising candidates for circularly polarized luminescence (CPL) light source, by attracting the broader scientific community for their applications in chiral optoelectronics and spintronics. However, it is still a great challenge to achieve both substantial photoluminescence asymmetry (gCPL) and high photoluminescence quantum yield (PLQY) simultaneously for high CPL brightness due to the limitations associated with magnetic transition dipole moments. Herein, this problem is overcome and achieve both large gCPL of 1.6×10−2 and PLQY of 56% in chiral perovskite through the magnetic element doping strategy. The substitution of Pb2+ ion with smaller magnetic Mn2+ ions shrinks the crystal lattice around [MnBr6]4− octahedra, amplifying the asymmetric distortion surrounding the Mn2+ ions. Moreover, the transition associated with Mn2+ ions can harvest the photoexcitation energy in chiral perovskites, and its spin‐flipping characteristics enable highly efficient CPL from the d–d transition on Mn2+ energy levels. Furthermore, this magnetic element doping strategy is proven to be a universal tactic for enhancing CPL brightness as confirmed in a series of 1D‐ or 2D‐chiral perovskites with various chiral ligands or halogens. The findings provide an in‐depth understanding of the structure‐property relationship in chiral perovskites toward chiral optoelectronic and spintronic applications. [ABSTRACT FROM AUTHOR]

New Nd3+-doped cadmium molybdato-tungstates with the chemical formula of Cd1−3x▯xNd2x(MoO4)1−3x(WO4)3x (where x = 0.0283, 0.0455, 0.0839, 0.1430, 0.1875, 0.2000, 0.2500, and ▯ denotes a vacant site in the crystal lattice) were successfully synthesized by the high-temperature solid state reaction method, using CdMoO4 and Nd2(WO4)3 as the initial reactants. The structure and change in their lattice parameters as a function of Nd3+ ion concentration were investigated by the XRD (X-ray diffraction) method. The surface morphology and grain size of the doped materials were characterized by SEM (scanning electron microscopy). Their thermal properties and initial reactants were analyzed by DTA-TG (differential thermal analysis coupled with thermogravimetry) techniques. The optical properties of the Nd3+-doped cadmium molybdato-tungstates, such as optical band gap, were determined by UV–vis–NIR (ultraviolet–visible–near infrared) spectroscopy. The EPR (electron paramagnetic resonance) technique provided information on the type of magnetic interactions between Nd3+ ions. [ABSTRACT FROM AUTHOR]

A set of AgxCu1 – xGaSe2 (0 ≤ x ≤ 1) solid solution powders has been prepared by solid-state synthesis. Using a combination of X-ray diffraction analysis and Raman spectroscopy, it has been found that the samples have a single-phase tetragonal structure (space group I-42d). It has been shown that their crystal lattice parameters do not follow Vegard's law up to x ≈ 0.4. It has been revealed that the band gap of the samples also changes nonlinearly: initially it decreases and then increases. Studies of the low-temperature luminescence and microwave photoconductivity decay spectra have shown that a set of samples with x of 0 to ~0.4 and further in the region with x > 0.4 is characterized by an increase in the photogenerated current carrier lifetime in AgxCu1 – xGaSe2 powders. The observed effect is apparently attributed to the replacement of deep charge carrier traps, such as selenium vacancies, by shallower cation vacancies. [ABSTRACT FROM AUTHOR]

A medium‐grade, poorly weathered CO3‐type meteorite was subjected to artificial space weathering by 1 keV protons in three subsequent steps, with gradually increasing doses from 1011 to 1017 protons per cm2. The resulting mineral modifications were identified by Raman spectroscopy, with specific emphasis on main minerals such as olivine (bands: 817, 845 cm−1), pyroxene (1007 cm−1), and partly amorphous feldspar (509 cm−1), considering variation in band shift and bandwidth (full width at half maximum, FWHM). After the first and second irradiations, variable band position changes were observed, probably from metastable alterations by Mg loss of the minerals, while the third stronger irradiation showed band shift dominated by amorphization. The olivine and pyroxene show weak increase in FWHM after the first irradiation, while more changes happened after the second and third irradiations. The flux after the third irradiation was higher than in other works, caused stronger damage in crystal lattice, partly resembling to dimerization as described by shock metamorphism. The glassy feldspar was characterized by high FWHM values already at the beginning, indicating weak crystallinity already that become even less crystallized, thus their bands disappeared after the third irradiation. Bands of hydrous minerals (goethite clay, chlorite) were not visible after the third irradiation, confirming some earlier results in the literature. Based on our results, moderately fresh surfaces could show stochastic but small spectral differences compared to the fresh most meteorites by metastable mineral alterations. The interpretation of Raman spectra of heavily space‐weathered surfaces could further benefit from the joint evaluation of alteration induced by both shock impact alteration and space weathering. [ABSTRACT FROM AUTHOR]

The electronic properties of moiré heterostructures depend sensitively on the relative orientation between layers of the stack. For example, near-magic-angle twisted bilayer graphene (TBG) commonly shows superconductivity, yet a TBG sample with one of the graphene layers rotationally aligned to a hexagonal Boron Nitride (hBN) cladding layer provided experimental observation of orbital ferromagnetism. To create samples with aligned graphene/hBN, researchers often align edges of exfoliated flakes that appear straight in optical micrographs. However, graphene or hBN can cleave along either zig-zag or armchair lattice directions, introducing a 30° ambiguity in the relative orientation of two flakes. By characterizing the crystal lattice orientation of exfoliated flakes prior to stacking using Raman and second-harmonic generation for graphene and hBN, respectively, we unambiguously align monolayer graphene to hBN at a near-0°, not 30°, relative twist angle. We confirm this alignment by torsional force microscopy of the graphene/hBN moiré on an open-face stack, and then by cryogenic transport measurements, after full encapsulation with a second, nonaligned hBN layer. This work demonstrates a key step toward systematically exploring the effects of the relative twist angle between dissimilar materials within moiré heterostructures. [ABSTRACT FROM AUTHOR]

Mesocrystals are ordered nanoparticle superstructures, often with internal porosity, which receive much recent research interest in catalysis, energy storage, sensors, and biomedicine area. Understanding the mechanism of synthetic routes is essential for precise control of size and structure that affect the function of mesocrystals. The classical synthetic strategy of mesocrystal was formed via self-assembly of nanoparticles with a faceted inorganic core but a denser (or thicker) shell of organic molecules. However, the potential materials and synthetic handles still need to be explored to meet new applications. In this work, we develop a non-classical synthetic strategy for organic molecules, such as tetrakis (4-hydroxyphenyl) ethylene (TPE-4OH), tetrakis (4-bromophenyl) ethylene (TPE-4Br), and benzopinacole, to produce mesocrystals with composed of microrod arrays via co-solvent-induced crystal transformation. The aligned nanorods are grown epitaxially onto organic microplates, directed by small lattice mismatch between plates and rods. Thus, the present work offers general synthetic handle for establishing well-organized organic mesocrystals. [ABSTRACT FROM AUTHOR]

A nonlocal phase-field crystal (NPFC) model is presented as a nonlocal counterpart of the local phase-field crystal (LPFC) model and a special case of the structural PFC (XPFC) derived from classical field theory for crystal growth and phase transition. The NPFC incorporates a finite range of spatial nonlocal interactions that can account for both repulsive and attractive effects. The specific form is data-driven and determined by a fitting to the materials structure factor, which can be much more accurate than the LPFC and previously proposed fractional variant. In particular, it is able to match the experimental data of the structure factor up to the second peak, an achievement not possible with other PFC variants studied in the literature. Both LPFC and fractional PFC (FPFC) are also shown to be distinct scaling limits of the NPFC, which reflects the generality. The advantage of NPFC in retaining material properties suggests that it may be more suitable for characterizing liquid–solid transition systems. Moreover, we study numerical discretizations using Fourier spectral methods, which are shown to be convergent and asymptotically compatible, making them robust numerical discretizations across different parameter ranges. Numerical experiments are given in the two-dimensional case to demonstrate the effectiveness of the NPFC in simulating crystal structures and grain boundaries. [ABSTRACT FROM AUTHOR]