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[Display omitted] • The doped Na+ ions as pillars diminish the alteration of the crystal lattice during electrochemical cycling. • The formation of surface oxygen vacancies induced by Na+ doping enhances the interface stability. • The doped Na+ ions result in the much higher utilization of Li 2 MnO 3. Structure engineering of the Li-rich layered cathodes to overcome insufficient structural stability and the rapid decay of capacity and voltage is crucial for commercializing of the materials for the lithium-ion batteries. Alkali metal element doping at the lithium sites has proven to be a feasible approach to boost the performance of the Li-rich layered oxides. Herein, the Na+-doping strategy in the lithium slabs is introduced to modify the structure of the cobalt-free layered Li-rich oxide, Li 1.2 Ni 0.2 Mn 0.6 O 2. It is revealed that the doped Na+ ions can promote the activation of the Li 2 MnO 3 phase, endowing the materials with high initial discharge capacity of 284.2 mAh g−1 at 0.1C. Due to the pillaring effect of the doped Na+ ions in the lithium slabs and the induced formation of oxygen vacancies, the electrochemical stability of the material is significantly improved, providing a capacity retention of 94.0 % after 100 cycles at 0.5C. The voltage decay per cycle is only 2.0 mV, less than 3.2 mV of the Li 1.2 Ni 0.2 Mn 0.6 O 2. The results suggest that the facile strategy of introducing Na+ ions into the lithium slabs is an efficient approach for optimizing structure design of the Li-rich layered oxides for the lithium-ion batteries. [ABSTRACT FROM AUTHOR]

The present study is a continuation of our previous work, where we synthesized and characterized t-ZrO 2 nanocrystals through the combustion method. Further, t-ZrO 2 nanocrystals are annealed at 600, 900, 1200, and 1400°C and characterized through XRD, Raman, FESEM, XPS, photoluminescence (PL), and thermoluminescence (TL) techniques. XRD and Raman patterns reveal that the as-synthesized ZrO 2 nanocrystals exhibit a tetragonal phase, and annealing at different temperatures induces phase transformations. Annealing at 600 °C restores the metastable nature of the tetragonal phase, although monoclinic nucleation is visualized through Raman spectroscopy. Annealing at higher temperatures leads to a complete transformation into the monoclinic phase. FESEM micrographs reveal extensive crystal growth and consolidation upon annealing. XPS analysis shows a reduction in the binding energies of the Zr 3d doublet due to the removal of lattice oxygen and the formation of oxygen vacancies upon annealing. The annealing of the synthesized material at 1400 °C induced a transformation to ferromagnetic behaviour at 300 K, with increased saturation magnetization (Ms) and coercivity (Hc), reflecting the stabilization of magnetic ordering and residual defects in the grain boundary. PL responses confirm the formation of luminescent defects in the crystal lattice. The TL response varies with the crystalline phase, annealing temperature, and radiation dose, suggesting defect creation, migration, and localization in the lattice. Overall, the study provides valuable insights into the structural and optical properties of ZrO 2 nanoparticles annealed at different temperatures. [ABSTRACT FROM AUTHOR]

In this work, Ni2+ was doped into the crystal lattice of LiFePO4 to improve the electrochemical performance. Lengths of the Li–O bonds in LiFe0.98Ni0.02PO4/C (2% NiSO4-doped LiFePO4) is longer than that of the bare LiFePO4 sample, the micromorphology of LiFe0.98Ni0.02PO4/C sample becomes uniform, and the Ni2+ doped into LiFePO4 expands the crystal plane spacing, which is conducive to Li+ diffusion. Amongst all the doped samples, the Li+ diffusion coefffcient of LiFe0.98Ni0.02PO4/C is the largest, and the redox peak of LiFe0.98Ni0.02PO4/C is more symmetrical, sharper and narrower, indicating that the proper amount of Ni2+-modified LiFePO4 can improve the electrochemical performance. Specific discharge capacity at 1C is 152 mAh g−1 when the doping amount is 2%. Additionally, after 200 cycles at 2C, the discharge specific capacity can be attained at 140 mAh g−1 and capacity retention rate reached 98%. [ABSTRACT FROM AUTHOR]

Using the method of non‐reactive sintering of nanocrystalline powders, highly transparent samples of optical ceramics based on solid solutions of yttrium‐scandium aluminum garnets containing 50 at.% scandium in the dodecahedral position and doped with erbium (1 at.%) and ytterbium (0–49 at.%) cations (YSAG:Yb:Er) were produced. The influence of Yb3+ concentration on the crystal lattice parameter, density, refractive index, stability of YSAG:Yb:Er solid solutions during high‐temperature sintering, thermal conductivity, optical transmittance and absorption coefficients in the wavelength range from 200 to 1100 nm, as well as Stokes and anti‐Stokes luminescence, was determined. The revealed patterns make it possible to fine‐tune the physical and chemical characteristics of ceramics for the design of composite laser materials. [ABSTRACT FROM AUTHOR]

Symmetry invariants of a group specify the classes of quasiparticles, namely the classes of projective irreducible co-representations in systems having that symmetry. More symmetry invariants exist in discrete point groups than the full rotation group O(3), leading to new quasiparticles restricted to lattices that do not have any counterpart in a vacuum. We focus on the fermionic quasiparticle excitations under "spin-space group" symmetries, applicable to materials where long-range magnetic order and itinerant electrons coexist. We provide a list of 218 classes of new quasiparticles that can only be realized in the spin-space groups. These quasiparticles have at least one of the following properties that are qualitatively distinct from those discovered in magnetic space group(MSG)s, and distinct from each other:(i) degree of degeneracy,(ii) dispersion as function of momentum, and(iii) rules of coupling to external probe fields. We rigorously prove this result as a theorem that directly relates these properties to the symmetry invariants, and then illustrate this theorem with a concrete example, by comparing three 12-fold fermions having different sets of symmetry invariants including one discovered in MSG. Our approach can be generalized to realize more quasiparticles whose little co-groups are beyond those considered in our work. The symmetry of free space greatly restricts the properties of quasiparticles that exist in free space. Solid state systems, with the discrete symmetry of the crystal lattice, have far fewer restrictions, and here, Fang et al find a vast array of new quasiparticles, with distinct energy dispersions or external field couplings that can only be realised in the spin-space group. [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]

We present an algorithm for the high-throughput computational discovery of intermetallic compounds in systems with a large number of components. It is particularly important for high entropy alloys (HEAs), where multiple principal elements can form numerous potential intermetallic compounds during the condensation process, making it challenging to predict the dominant phase. Our algorithm is based on a brute-force evaluation of candidate structures with a fixed underlying lattice (FCC or BCC) accelerated by machine-learning interatomic potentials. The algorithm takes a set of chemical elements and a crystal lattice type as inputs and produces structures on and near the convex hull of thermodynamically stable structures. The candidate structures are evaluated using the low-rank potential (LRP), trained to reproduce energies of structures equilibrated with density functional theory (DFT). Thanks to extreme computational effectiveness of the LRP, it is feasible to evaluate hundreds of thousands of structures per second, per CPU core. Thus, our algorithm screens a complete set of candidate structures for a given system without missing any configurations. We validated our method on systems with BCC (Nb-W, Nb-Mo-W, V-Nb-Mo-Ta-W) and FCC (Cu-Pt, Cu-Pd-Pt, Cu-Pd-Ag-Pt-Au) lattices and discovered 268 new alloys not reported in the AFLOW database1, which we used as a benchmark. [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]

The supramolecular structure of the crystal products–N-[2-chloro-2-(silatranyl)ethyl]-4-nitro-benzenesulfonamide 4d and N-chloro-N-[2-chloro-1-(silatran-1-yl-methyl)ethyl]benzene-sulfonamide 5a was established by X-ray diffraction analysis data, FTIR spectroscopy and DFT quantum chemical calculations. Their crystal lattice is formed by cyclic dimers with intermolecular hydrogen NH∙∙∙O-Si bonds and CH∙∙∙O=S short contacts. The distribution of electron density in the monomers was determined using quantum chemical calculations of their molecular electrostatic potential (MESP) in an isolated state (in gas) and in a polar medium. The transition from covalent N–Si bonds in crystal compounds and polar medium to non-covalent N∙∙∙Si bonds happened while performing the calculations on the monomer molecules and their dimers in gas. The effect of intermolecular interactions on the strength of the N–Si and N∙∙∙Si bonds in molecules was evaluated through calculations of their complexes with H2O and DMSO. [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]

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]

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]

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]

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]

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]

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 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]

In this study, we investigated the influence of the position and quantitative content of scandium in YSAG:Cr on the efficiency of chromium cation valence conversion. YSAG:Cr ceramic powders were synthesized using the chemical precipitation method. It was determined that the microstructure of ceramics and the luminescent properties of YSAG:Cr4+ depend on the predominant position of scandium, whether it replaces octahedral or dodecahedral positions in the garnet crystal lattice. An increase in Sc dod content contributed to a decrease in grain size and a shift of the emission peak of Cr4+ ions towards the short-wavelength region. Conversely, an increase in Sc oct content led to an increase in grain size and a shift of the maximum of the luminescent band towards the long-wavelength region. It was found that increasing the quantitative content of scandium in the octahedral position in the garnet structure by up to 50 % enhances the efficiency of the conversion of Cr3+ to Cr4+, while an increase in the proportion of Sc dod resulted in a decrease in conversion efficiency. [ABSTRACT FROM AUTHOR]

Optical ceramics with 50 at.% Sc in both dodecahedral ({Y 1·17 Er 0.03 Yb 0.3 Sc 1.5 }[Al 1.8 Sc 0.2 ]Al 3 O 12 , {Y 1.2 Yb 0.3 Sc 1.5 }[Al 1.8 Sc 0.2 ]Al 3 O 12) and octahedral ({Y 2·52 Er 0.03 Yb 0.3 Sc 0.15 }[Al 1.0 Sc 1.0 ]Al 3 O 12 , {Y 2.55 Yb 0.3 Sc 0.15 }[Al 1.0 Sc 1.0 ]Al 3 O 12) sites of the garnet structure were synthesized using the non-reactive vacuum sintering method. Analysis of the phase composition, thermal diffusivity, transmission in the visible and IR regions of the spectrum, as well as luminescent properties (Stokes and anti-Stokes luminescence, luminescence decay kinetics) revealed clear correlations with the chemical composition of ceramics. It has been determined that solid solutions in which Y3+ cations are partially replaced by Sc3+ cations, compared to solid solutions in which Al3+ cations in the octahedral site are partially replaced by Sc3+, are characterized by lower crystal lattice parameters (11.883 ± 0.004 Å and 12.153 ± 0.005 Å); lower thermal conductivity values (4.72 W/(m·K) and 5.9 W/(m·K)); higher characteristic vibration frequencies of structural groups; shorter lifetimes of excited states of Yb3+ (1.41 μs and 1.56 μs for YSAG:Yb; 0.42 μs and 0.65 μs for YSAG:Yb,Er) and Er3+ (8.6 μs and 9.2 μs) cations; higher efficiency of energy transfer from Yb3+ to Er3+. The results clearly indicate that solid solutions with high concentrations of Sc3+ cations in the dodecahedral site can also be effective matrices for Yb3+ and Er3+ cations compared to solid solutions with a predominant introduction of scandium in the octahedral site. [ABSTRACT FROM AUTHOR]

This work aims to present the building blocks for an all direct laser written integrated spectrometer in the mid-infrared (3.39–4.1 μm range) based on the SWIFTS (Stationary Wave Integrated Fourier Transform Spectrometer) principle. In a SWIFTS-Gabor configuration, the light from the source interferes with itself in the middle of a channel waveguide, creating a stationary wave. This interferogram is then sampled through scattering centers placed on top of the waveguide that radiate the light they extract onto a detector placed directly on the sample. Finally, the spectrum of the source is retrieved through a Fourier transform. To implement a SWIFTS, two main photonic functions are required: the waveguide and the scattering centers. In this work, both functions have been created using Direct Laser Writing (DLW), a versatile technique, allowing to easily access 3D configurations and to reduce fabrication time. DLW focuses a femtosecond laser onto a sample so as to locally change the crystal lattice, resulting in its structural modification. The waveguides presented here are surface half-circular cladding structures made through type II modifications in the sample, and the scattering centers are surface damage tracks (also referred to as grooves). These surface tracks are creating dielectric discontinuities in the evanescent part of the stationary wave, resulting in the light being radiated outside the waveguide. All of these are made in a z-cut lithium niobate substrate for future implementation of the electro-optic effect. We demonstrate that we have functional waveguides in the mid-IR and that our grooves are extracting the stationary wave as expected, showing promising results for future implementation of a complete mid-IR SWIFTS using DLW. [ABSTRACT FROM AUTHOR]

In this work, composites made of polylactide (PLA) and filled with alkali-pretreated rice husk (RH) were investigated. Composites containing 20, 30, and 40 wt.% of RH were synthesized. It was shown that alkaline treatment, along with the change in crystal lattice, led to an increase in the content of non-crystalline parts and the volume of intercrystalline spaces, and the internal surface of the cellulose fiber increased, which resulted in improved adhesion of the fiber with the matrix. The addition of rice husk to the PLA matrix led to an increase in the flexural modulus, which increased to 2881 MPa for the PLA/RH (80/20 wt.%) and 3034 MPa for the PLA/RH (70/30 wt.%) composites and lowered the peak load stress by approximately 43% for the composite with 20 wt.% RH and 56% for the composite with 30 wt.% RH. The reduction in the degree of PLA crystallinity allows macromolecules to move more freely in amorphous regions, which has a positive effect on increasing the flexibility of materials in general. The optimal formulation is a composite consisting of 30% RH and 70% PLA matrix. [ABSTRACT FROM AUTHOR]

Complex hydrides, such as sodium borohydride (NaBH4), are attractive materials for hydrogen storage because of their high hydrogen capacity. However, practical application of these materials is limited because of their unfavorable hydrogen thermodynamics and poor kinetics. Herein, it is demonstrated that the inclusion of BF4− in NaBH4 results in remarkable Na+ conductivity of 1.5 × 10−3 S cm−1, which is 10 000 times higher compared to pure NaBH4 (7.0 × 10−8 S cm−1) at 115 °C. The ionic conductivity is also comparable to values reported for some of the best borohydride‐based conductors reported to date. More remarkably, this improvement of ionic conductivity is found to be correlated to lower hydrogen release temperatures for BF4−‐modified NaBH4 releasing hydrogen at a temperature of 200 °C instead of 510 °C in the case of pristine NaBH4. Nudged elastic band calculations based on density functional theory reveal that partial substitution of the [BH4]− groups in NaBH4 by BF4− may lead to the formation of distortions within the NaBH4 crystal lattice with favorable channels for Na+ mobility enabling the release of hydrogen at low temperatures. [ABSTRACT FROM AUTHOR]

Zirconia dental ceramics have evolved from uniform blocks of 3 mol.% yttria (3Y) to strength- and color-graded blocks containing 3 mol.% and 5 mol.% components. Relatively little is known about the graded materials' compositions and microstructures. Concerns have been raised about aging and degradation. This study investigated the microstructure, elemental composition, and phase content of different zones of strength- and color-graded zirconia blocks using scanning electron microscopy, x-ray fluorescence, and x-ray diffraction. Specimens were made from green-state blocks using CAD/CAM machining and sintering. Two strength- and color-graded zirconia materials had different grain sizes, elemental compositions, and phase contents between their top and bottom zones, these data being internally consistent as well as being broadly consistent with prior compositional physical property data. A color-graded zirconia material did not exhibit substantial differences between its top and bottom zones, consistent with expectations and previously published data. Modeling phase content for complex yttria-doped zirconia crystal systems with multiple heterogeneous crystal lattices from XRD data was inherently difficult, which may account for the ranges among previously published data; authors should describe detailed methodologies. Detailed compositional data at the scale of the microstructure is needed to relate composition to phase content, physical behavior, including crack evolution. [ABSTRACT FROM AUTHOR]

Guanidine-containing molecules are an interesting class of compounds within both medicinal and material sciences. Having knowledge of their tautomerism is key in designing guanidines that interact with biological and chemical receptors. However, there are limited data on the solid-phase structure of N,N′-substituted guanidines. Thus, eleven guanidines bearing a 4,6-dimethylpyrimidyl at one end and substituents of varying sizes and electronic properties at the other side, were synthesised, crystallised, and analysed by X-ray crystallography. Calculations of isolated molecules of tautomer energies and bond lengths were performed for comparison. One class of guanidines crystallised as a cis–trans tautomer with the shorter bond directed towards the pyrimidyl unit. When more electron-deficient aniline substituents were inserted, the crystallised tautomer changed to a cis–cis form where the shorter bond was directed towards the aniline. The switch in the tautomer structure is concluded to be due to both the electronic properties of the substituents and the intermolecular hydrogen bonding in the crystal lattice. [ABSTRACT FROM AUTHOR]

The use of tris(4-aminophenyl)amine (TAPA) as central to the synthesis of both polyimines and polyimides and covalent organic frameworks and inorganic cages, among others, has grown in the last few years. The resulting materials exhibit high performance in their area of application. In this contribution, the crystal structures of two TAPA derivatives, triethyl (nitrilotris(benzene-4,1-diyl))tricarbamate (1) and triethyl 2,2′,2″-((nitrilotris(benzene-4,1-diyl))tris(azanediyl))tris(2-oxoacetate) (2), are described. The molecular and supramolecular structures of both compounds were compared between them and with analogous compounds. The analyses of their vibrational and 13C-CPMAS NMR spectroscopies, as well as their thermal stability, were included and corelated with the crystal structure. Hirshfeld surface analysis on the crystal structures of both TAPA derivatives revealed the stabilization of the crystal network via the amide N—H∙∙∙O interactions of dispersive nature in the carbamate, whereas dispersive carbonyl–carbonyl interactions also played a competitive role in the supramolecular arrangement of the oxamate. Interaction energy DFT calculations performed at the B3LYP/6-31G(d,p) level allowed us to estimate the energy contributions and nature of several interactions in terms of the stability of both crystal lattices. [ABSTRACT FROM AUTHOR]

The microstructure, phase composition and elemental composition in the α- and β-phases of the two-phase wrought Ti-5.7Al-1.6V-3Mo titanium alloy at room temperature were studied by transmission electron microscopy and X-ray energy-dispersive spectroscopy. The temperature ranges of phase transformations in the alloy during heating from 298 to 1523 K were studied by differential scanning calorimetry (DSC). Two endothermic peaks were observed on the DSC curve at the temperatures of 1078 K and 1207 K, and one exothermic peak was observed at a temperature of 1123 K. The endothermic peak on the DSC curve at a temperature of 1078 K is due to the formation of α″-martensite, at a temperature of 1207 K is caused by α → β phase transformation. The exothermic peak at a temperature of 1123 K, presumably, corresponds to the polymorphic transformation of brookite → rutile in TiO2 oxide. High-temperature synchrotron studies were carried out from room temperature to 1373 K. It was found that the increase in lattice parameters during heating is nonlinear. Possible mechanisms of the nonlinear change in the lattice parameters at temperatures above 1200 K are discussed. At T > 1000 K α″-martensite was formed by β → α″ phase transformation. An increase in the volume fraction of α″-phase with increase in temperature was accompanied by a decrease in the volume fraction of β-phase. An increase in microstrain of the α-phase lattice and a decrease in microstrain of the β-phase lattice were observed upon heating. [ABSTRACT FROM AUTHOR]

The lattice mismatch between γ-CuI and Al2O3 (sapphire) is as large as 27.1% due to differences in crystal systems and lattice constants. To achieve epitaxial growth on the initial surface of the substrate, lattice mismatch can be minimized through domain matching. In this work, the γ-CuI film was epitaxially grown on the Al2O3(001) substrate by employing the physical vapor transport technology. The morphology, structure, and rotation domain matching of the films were investigated via SEM, XRD, electron backscatter diffraction, and STEM/TEM. The results revealed that the film grew preferentially along the (111) plane, and the full width at half maximum of the (111) diffraction peak in the rocking curve was 0.45°, which indicated the high degree of crystallinity of the film. The surface of the γ-CuI film exhibited two kinds of triangular crystal domains with a relative rotation angle of ∼60°. The interior of the crystal domains possessed a step-like structure. The two types of triangular crystal domains in the film were attributed to different rotation domains, and the interface was ascribed to the ⟨111⟩ 60° twin boundaries. The epitaxial matching mode was found to be CuI ⟨11 2 ̄ ⟩ (111)//Al2O3 [ 1 ̄ 1 ̄ 0] (001), resulting in ∼4.6% lattice mismatch between γ-CuI and Al2O3 along the Al2O3 ⟨ 1 ̄ 10 ⟩ direction, which is significantly lower than previously reported data. [ABSTRACT FROM AUTHOR]

An estimation of category of liquid crystalline (LC) phase based on composite lattices using linear algebra and lattice parameters is proposed. The vector space in three dimensions (3 D) is dissolved in the initial phase into two dimensions (2 D) , and one dimension (1 D) subspace in a 3D crystal, respectively, rotate and/or slide between each other during thermal process. In linear algebra, this state is designated as [ 2 D ⊕ 1 D ] composite subspaces of vector. As per linear algebraic approach, [ 2 D ⊕ 1 D ] is not identical with 3D, and the mathematical sign ⊕ indicates addition directly. The phase is represented as [ 2 D ⊕ 1 D ] lattice-based composite phase. Apart from the [ 2 D ⊕ 1 D ] phase, two more mixed phases with [ 1 D ⊕ 1 D ] and [ 1 D ⊕ 1 D ⊕ 1 D ] may also be theoretically studied using linear algebra. Finally, the category of phase is proposed to be analyzed with link to its transition temperature. [ABSTRACT FROM AUTHOR]

[Display omitted] The serious combination of abundant electrons/holes in bulk primarily hinders the efficiency in the photocatalytic reaction. It is crucial to control the spatial charge dynamics through delicately designing the crystal configuration of photocatalyst. In this work, a modified tungsten trioxide nanosheet colloid (M-WO 3) was synthesized by an ion exchange method. Compared to pristine WO 3 (P-WO 3), the crystal lattice vibration frequency of M-WO 3 increases from 2.8 meV to 4.3 meV, which effectively prohibits electron–phonon coupling and powerfully accelerates the separation and transfer of photoinduced charge carriers. Irradiated by visible-light, M-WO 3 shows much higher photocatalytic bacterial inactivation performance than P-WO 3. In addition, this regulation method increases the surface charges of the WO 3 colloid to improve its stability, which endows this colloid photocatalyst with broad prospects in practical photocatalytic antibacterial applications. This work offers guidance to construct efficiently separated photoinduced electron/hole pairs of the colloid photocatalyst by designing its crystal structure. [ABSTRACT FROM AUTHOR]

Here we review scanning tunneling microscopy research on the surface determination for various types of kagome materials, including 11-type (CoSn, FeSn, FeGe), 32-type (Fe3Sn2), 13-type (Mn3Sn), 135-type (AV3Sb5, A = K, Rb, Cs), 166-type (TbMn6Sn6, YMn6Sn6 and ScV6Sn6), and 322-type (Co3Sn2S2 and Ni3In2Se2). We first demonstrate that the measured step height between different surfaces typically deviates from the expected value of ±0.4 ∼0.8Å, which is owing to the tunneling convolution effect with electronic states and becomes a serious issue for Co3Sn2S2 where the expected Sn-S interlayer distance is 0.6Å. Hence, we put forward a general methodology for surface determination as atomic step geometry imaging, which is fundamental but also experimentally challenging to locate the step and to image with atomic precision. We discuss how this method can be used to resolve the surface termination puzzle in Co3Sn2S2. This method provides a natural explanation for the existence of adatoms and vacancies, and beyond using unknown impurity states, we propose and use designer layer-selective substitutional chemical markers to confirm the validity of this method. Finally, we apply this method to determine the surface of a new kagome material Ni3In2Se2, as a cousin of Co3Sn2S2, and we image the underlying kagome geometry on the determined Se surface above the kagome layer, which directly visualizes the p-d hybridization physics. We emphasize that this general method does not rely on theory, but the determined surface identity can provide guidelines for first-principles calculations with adjustable parameters on the surface-dependent local density of states and quasi-particle interference patterns. [ABSTRACT FROM AUTHOR]

Changes in the phase composition of serpentinite from the Zhitikarinsky deposit (Kazakhstan) were studied during heat treatment in the temperature range of 105–800 °C in order to determine the phase that leads to an increase in the reactivity of serpentinite during interactions with acids. In accordance with this, the task was set to consider the influence of temperatures (105 °C, 600 °C, 660 °C, 725 °C, 750 °C and 800 °C), selected according to the extreme points of the main transformations from its derivatogram, on changes in the phase composition. The effects of heat treatment on the phase composition and reactivity of serpentinite during interactions with sulfuric acid were studied and discussed using the diffraction patterns of serpentinite heat treated at selected temperatures for 1 h and using methods of thermodynamic evaluation of the possible reactions in the temperature range of 350–750 °C, as well as establishing the nature of their interaction with sulfuric acid under identical conditions. It has been shown that, in the range of 600–750 °C, the crystal lattice of the structural composition of serpentinite is completely destroyed with the formation of not only magnesium silicates but possibly also magnesium oxide, which leads to the thermal activation of serpentinite in relation to interactions with acids and the improvement of the technological process of extracting magnesium from it. The greatest increase in reactivity was found in serpentinite samples heat treated at temperatures of 725 °C and 750 °C, which can be recommended for the thermal activation of serpentinite before using acid methods to improve the technological performance of the process of extracting magnesium from serpentinite. [ABSTRACT FROM AUTHOR]

The internal modification with rare earth ion doping proved to be a very effective strategy for improving the luminescent properties of NaYF 4 -based upconversion materials. However, greatly enhancing the luminescence efficiency of NaYF 4 :Yb3+/Er3+ remains a major challenge. Herein, the effects of Sn4+ doping on the structure and luminescent performance of such material were explored. The hydrothermal molten-salt method was applied to synthesize the Sn4+-doped NaYF 4 :Yb3+/Er3+ upconversion materials, and their crystal structures, morphologies, surface chemical composition and element states, and luminescence performance were characterized. It was found that Sn4+ doping can significantly enhance the luminescence intensity and tailor the chromaticity of NaYF 4 :Yb3+/Er3+. In particular, the green (G) and red (R) luminescence intensity levels of the 30 mol% Sn4+ doped material were increased by factors of 26.97 and 38.91, respectively. The R/G ratio was incremented from 0.34 for the undoped material to 0.83 for the 40 mol% Sn4+ doped counterpart. The Sn4+ doping led to the change of lattice distortion and crystal growth pattern of NaYF 4 :Yb3+/Er3+. The mechanism for Sn4+ doping to affect the luminescence properties of the prepared upconversion material was also explored. The changes in luminescence intensity levels and R/G ratios could be attributed to the highly asymmetric distorted lattice and crystal field resulting from Sn4+ doping. [ABSTRACT FROM AUTHOR]

The kinetics of phase transformations in the nitriding process α-Fe → γ'-Fe4N → ε-Fe3-2N of the pre-reduced iron ammonia synthesis catalyst was investigated under in situ conditions (atmospheric pressure, 350 °C) by measuring changes of mass, gas phase composition, and magnetic permeability in a differential tubular reactor. The iron nanocrystallite size distribution according to their specific active surface areas was measured, and it was found that the catalyst is bimodal as the sum of two Gaussian distributions, also differing in the value of the relative magnetic permeability. Relative magnetic permeability of small α-Fe crystals in relation to large crystals is higher by 0.02. In the area of α → γ' transformation, the magnetic permeability dependencies change, proving the existence of two mechanisms of the α-Fe structure change in the α-Fe → γ'-Fe4N transformation. In the first area, a solution of α-Fe (N) is formed with a continuous and insignificant change of the crystal lattice parameters of the iron lattice. In the second area, there is a step, oscillatory change in the parameters of the iron crystal lattice in FexN (x = 0.15, 0.20, 0.25 mol/mol). In the range of γ'-Fe4N → ε-Fe3-2N transformation, a solution is formed, with nitrogen concentration varying from 0.25–0.45 mol/mol. During the final stage of the nitriding process, at a constant value of the relative magnetic permeability, only the concentration of nitrogen in the solution εr increases. The rate of the phenomenon studied is limited by a diffusion rate through the top layer of atoms on the surface of iron nanocrystallite. The estimated value of the nitrogen diffusion coefficient varied exponentially with the degree of nitriding. In the area of the solution, the diffusion coefficient is approximately constant and amounts to 5 nm2/s. In the area of oscillatory changes, the average diffusion coefficient changes in the range of 3–11 nm2/s, and is inversely proportional to the nitrogen content degree. The advantage of the research method proposed in this paper is the possibility of simultaneously recording, under reaction conditions, changes in the values of several process parameters necessary to describe the process. The research results obtained in this way can be used to develop such fields of knowledge as heterogeneous catalysis, materials engineering, sensorics, etc. [ABSTRACT FROM AUTHOR]

In this investigation, an effort was made to introduce Ag into the CeO2 fluorite crystal lattice to form Ce0.99Ag0.01O2-δ (ACRM) using an ammonium hydroxide-assisted co-precipitation method. The resulting powder obtained after the co-precipitation reaction, filtration, and drying was annealed at 800 °C in a muffle furnace to obtain crystalline ACRM. The phase composition and microstructure of the synthesized ACRM were analyzed using a powder X-ray diffractometer (PXRD) and a scanning electron microscope (SEM). The characterized ACRM powder was then subjected to multiple thermochemical thermal reduction (TR) and CO2 splitting (CDS) cycles using a high-temperature thermogravimetric analyzer (TGA). The TR step was conducted using Ar gas as an inert atmosphere, maintaining the temperature at 1400 °C for 60 min. Subsequently, the same powder was subjected to the CDS step by treating it with a gaseous mixture of 50% CO2 and Ar gas at 1000 °C for 30 min. ACRM displayed stable redox reactivity towards thermochemical CDS cycles by generating an average of 50.9 μmol of O2/g·cycle and 101.6 μmol of CO/g·cycle, respectively, over 10 thermochemical cycles. [ABSTRACT FROM AUTHOR]

Phase transitions are typically quantified using order parameters, such as crystal lattice distances and radial distribution functions, which can identify subtle changes in crystalline materials or high‐contrast phases with large structural differences. However, the identification of phases with high complexity, multiscale organization and of complex patterns during the structural fluctuations preceding phase transitions, which are essential for understanding the system pathways between phases, is challenging for those traditional analyses. Here, it is shown that for two model systems— thermotropic liquid crystals and a lyotropic water/surfactant mixtures—graph theoretical (GT) descriptors can successfully identify complex phases combining molecular and nanoscale levels of organization that are hard to characterize with traditional methodologies. Furthermore, the GT descriptors also reveal the pathways between the different phases. Specifically, centrality parameters and node‐based fractal dimension quantify the system behavior preceding the transitions, capturing fluctuation‐induced breakup of aggregates and their long‐range cooperative interactions. GT parameterization can be generalized for a wide range of chemical systems and be instrumental for the growth mechanisms of complex nanostructures. [ABSTRACT FROM AUTHOR]

A vanadium ion valence state constant high-entropy perovskite system was synthesized using the hydrothermal method with a trivalent vanadium ion as the vanadium source. The B-site of the perovskite crystal lattice was loaded with five atoms in equal proportions. We tried to synthesize the Sr(TiZrHfVNb)O3 high-entropy system using different methods. However, the valence state of the vanadium ion could only be kept constant using the hydrothermal process in the valence balanced high-entropy composition system. There was significant vanadium element segregation and second phase in the Sr(TiZrHfVNb)O3 system prepared using the solid-state reaction process. Also, obvious vanadium ion valence state ascending from V3+ to V5+ appeared in this high-entropy system with an increase in calcination temperature. Inconspicuous vanadium element segregation appeared at 900 °C, the significant segregation phenomenon and second phase appeared at 1200 °C, and the particle size increased with the temperature. This meant that the high-entropy value could not only stabilize the crystal phase, but also stabilize the ionic valence state. Moreover, the constant trivalent vanadium ion valence state could provide coordinated performance with a wide optical response range and a low band gap for the high-entropy system. This suggests that the system might grow a potential ceramic material for optical applications. [ABSTRACT FROM AUTHOR]

Nanomaterials based on manganese oxides (MnOx) show considerable potential for large-scale electrochemical energy storage devices, driving significant research to explore their capabilities. One intriguing approach to enhance their performance involves the incorporation of other metals within their structure. Thus, we analyzed hierarchically obtained Cobalt (Co)-doped MnOx nanowires with different Co content, examining their storage properties. Notably, the initial impact of Co was observed in the structural characteristics of MnOx-based nanowires. As the Co content increased, there was a noticeable decrease in the cross-sectional widths of these nanowires. Also, we observed by XRD analysis that Co could effectively substitute manganese (Mn) within the crystal lattice. By XPS, the impact of Co doping on the Mn(IV)/Mn(III) ratio was of particular significance, as this ratio exhibited a direct correlation with the Co content (more Co, higher Mn(IV)/Mn(III) ratio), emphasizing the pivotal role of Co in modulating the oxidation states within these materials. Electrochemical studies revealed a remarkable dual behavior in the nanowires, combining pseudocapacitance and battery-like energy storage characteristics. Notably, our investigation uncovered a distinctive storage performance trend resembling a volcano, with the optimal energy storage material achieved using 1.4 wt.% Co-doped MnOx–Co nanowires. Applying the optimum material for a hybrid supercapacitor application, the energy and power density values were calculated as 48.08 Wh kg−1 and 2339.02 W kg−1, respectively. Thus, we believe that our comprehensive exploration of Co-doped MnOx nanowires provides valuable insights into understanding these materials' optimization for energy storage applications. [ABSTRACT FROM AUTHOR]

The key objective of this study is to determine the effect of interphase boundaries, the formation of which is caused by the variation of Li2ZrO3/MgLi2ZrO4 phases in lithium-containing ceramics based on lithium metazirconate, on the resistance to near-surface layer destruction processes associated with irradiation with He2+ ions. During the observation of the deformation effects that have an adverse impact on the volumetric swelling of the near-surface layers of ceramics, the thermal expansion factor caused by high-temperature irradiation was considered, simulating conditions as close as possible to the operating conditions of these materials as blankets for tritium propagation. During the studies conducted, it was established that an elevation in the contribution of MgLi2ZrO4 in the composition of ceramics leads to a rise in resistance to deformation swelling caused by structural distortions of the crystal lattice, due to a decrease in the effect of thermal expansion, alongside the presence of interphase boundaries. The established dependencies of the change in the hardness of the near-surface layer of the studied ceramics made it possible to establish the kinetics of softening caused by the deformation distortion of the crystalline structure, as well as to determine the relationship between volumetric swelling and softening (change in hardness) and a decrease in crack resistance (change in the value of resistance to single compression). [ABSTRACT FROM AUTHOR]

The fluorescence intensity of lanthanide (Ln3+)-doped upconversion (UC) materials generally exhibits significant thermal quenching with increasing temperature, which is a critical challenge for their application. In this work, Yb2−xW3O12:xHo phosphors with thermally enhanced UC luminescence are fabricated by a facile solid-state sintering method. The x-ray diffraction (XRD) patterns reveal that the Yb2−xW3O12:xHo samples have a pure phase, which indicates that the Ho3+ ions are successfully doped into the crystal lattice of Yb2W3O12. In addition, the in situ XRD patterns show that when the temperature is increased, the diffraction peaks gradually shift to a higher angle, clearly illustrating the negative thermal expansion phenomenon of Yb2W3O12. The UC luminescence shows that Yb2−xW3O12:xHo phosphors have red and green emissions when excited by a 980 nm laser diode. By changing the doping amount of Ho, it has been found that the luminescence is strongest at 2 mol%. Further investigation of the temperature-dependent upconversion emission properties of Yb2−xW3O12:xHo samples shows that the red emission increases by several times from 323 K to 498 K. The temperature-sensing characteristics of Yb2−xW3O12:xHo are studied using fluorescence intensity ratio (FIR)-based technology. The maximum relative sensitivity and the maximum absolute sensitivity are calculated as 2.04%/K at 323 K and 0.066/K at 498 K, respectively. These results indicate that Yb2−xW3O12:xHo fluorescent powder can be used for optical temperature measurement. [ABSTRACT FROM AUTHOR]

Li4Ti5O12 (LTO) is known for its zero-strain characteristic in electrochemical applications, making it a suitable material for fast-charging applications. Here, we systematically studied the quasi-equilibrium and non-equilibrium lithium-ion transportation kinetics in LTO thin-film electrodes, across a range of scales from the crystal lattice to the microstructured electrodes. At the crystal lattice scale, during the non-equilibrium lithiation process, lithium ions are dispersedly embedded into the 16c position, resulting in more 8a → 16c migration compared with the quasi-equilibrium lithiation, and forming numerous fast lithium diffusion channels inside the LTO lattice. At the microstructural electrode scale, optical spectrum characterizations supported the "nano-filaments" lithiation model in polycrystalline LTO thin-film electrodes during the lithiation process. Our results reveal the patterns of lithium migration and distribution within the LTO thin film electrode under the non-equilibrium and quasi-equilibrium lithiation process, offering profound insights into the potential optimization strategies for enhancing the performance of fast-charging thin film batteries. Li4Ti5O12 (LTO) is an ideal battery material for fastcharging applications. The authors examine Li+ transport in LTO thin film electrodes, revealing that nonequilibrium processes result in unique Li+ occupation states that enhance Li+ diffusion. Findings suggests engineering Li+ occupations in LTO crystal lattice can improve battery performance. [ABSTRACT FROM AUTHOR]

β-Ga2O3 is an ultra-wide bandgap semiconductor (Eg~4.8 eV) of interest for many applications, including optoelectronics. Undoped Ga2O3 emits light in the UV range that can be tuned to the visible region of the spectrum by rare earth dopants. In this work, we investigate the crystal lattice recovery of (2 ¯ 01) -oriented β-Ga2O3 crystals implanted with Yb ions to the fluence of 1 ×1014 at/cm2. Post-implantation annealing at a range of temperature and different atmospheres was used to investigate the β-Ga2O3 crystal structure recovery and optical activation of Yb ions. Ion implantation is a renowned technique used for material doping, but in spite of its many advantages such as the controlled introduction of dopants in concentrations exceeding the solubility limits, it also causes damage to the crystal lattice, which strongly influences the optical response from the material. In this work, post-implantation defects in β-Ga2O3:Yb crystals, their transformation, and the recovery of the crystal lattice after thermal treatment have been investigated by channeling Rutherford backscattering spectrometry (RBS/c) supported by McChasy simulations, and the optical response was tested. It has been shown that post-implantation annealing at temperatures of 700–900 °C results in partial crystal lattice recovery, but it is accompanied by the out-diffusion of Yb ions toward the surface if the annealing temperature and time exceed 800 °C and 10 min, respectively. High-temperature implantation at 500–900 °C strongly limits post-implantation damage to the crystal lattice, but it does not cause the intense luminescence of Yb ions. This suggests that the recovery of the crystal lattice is not a sufficient condition for strong rare-earth photoluminescence at room temperature and that oxygen annealing is beneficial for intense infrared luminescence compared to other tested environments. [ABSTRACT FROM AUTHOR]

Thermoacid behavior of serpentinite from the Zhitikarinsky field (g. Zhitikara, Kazakhstan). The character of dissolution of heat-treated serpentinite in a narrow temperature range of 600–750 °C is investigated, where the crystal lattice of the structural structure of chrysotile in sulfuric acid is destroyed. The X-ray and chemical analysis of the products of dissolution of heat-treated serpentinite at 600 °C, 725 °C and 750 °C in sulfuric acid solution show that the reason for the increase in the reactivity of heat-treated serpentinite at 725 °C and 750 °C with respect to the acidic medium and the degree of magnesium extraction into sulfate solution is the formation of periclase (MgO) in the serpentinite composition after heat treatment of them within a temperature range of 600–750 °C. The results were discussed using data obtained by conducting a thermodynamic evaluation of probable reactions during the thermoacid treatment of serpentinite, phase compressions of heat-treated serpentinite at 600–750 °C, and after its acid treatment at 1.0 M H2SO4. [ABSTRACT FROM AUTHOR]