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In this study, we propose a coaxial composite resonator (CCR) structural unit and experimentally demonstrate that a periodic structural plate composed of CCR units effectively suppresses low-frequency vibrations. Each CCR unit comprises a cylindrical resonant element, a steering wheel-shaped elastic connection, and a framework structure. These components collectively generate elastic wave bandgaps through the intrinsic damping properties of the resonant elements. Finite element analysis was employed to investigate the influence of key parameters on the bandgap (BG) characteristics of the CCR structure. The results indicate that the resonator mass is the primary determinant of the BG onset frequency, with larger resonator masses leading to a lower onset frequency. Additionally, the lattice constant was identified as the most sensitive parameter influencing the BG width, such that an increased lattice constant results in an expanded frequency range of the BG. The validity of the finite element models and the predicted BG properties were confirmed through experimental testing. The CCR structure exhibits significant potential for applications in low-frequency vibration and noise control. [ABSTRACT FROM AUTHOR]

Finite size scaling for a first order phase transition, where a continuous symmetry is broken, is tested using an approximation of Gaussian probability distributions with a phenomenological "degeneracy" factor. Predictions are compared to the data from Monte Carlo simulations of the Lebwohl–Lasher model on L × L × L simple cubic lattices. The data show that the intersection of the fourth-order cumulant of the order parameter for different lattice sizes can be expressed in terms of the relative degeneracy q = 4π of the ordered and disordered phases. This result further supports the concept of universality at first order transitions developed recently. [ABSTRACT FROM AUTHOR]

The effect of cadmium ions introduced into fluorophosphate glass on the growth and photoluminescence (PL) of the CsPb1–xCdxBr3 perovskite nanocrystals (NCs) is systematically studied. The x-ray diffraction patterns have shown that cadmium ions are really incorporated into the NCs that results in a decrease in the lattice constant from 5.85 (x = 0) to 5.75 Å (x = 0.45). At the large cadmium content in the glass (x > 0.38), simultaneous formation of the perovskite CsPb1–xCdxBr3 NCs and the non-luminescent CsCdBr3 NCs in the hexagonal phase is found. It is also found that the lattice contraction leads to an increase in the bandgap energy and a noticeable shift of the PL band to the blue region of the spectrum (from 2.42 to 2.68 eV) with a drop in quantum yield from 85% for CsPbBr3 NCs down to 4% for CsPb0.55Cd0.45Br3 NCs. It is shown that the PL quantum yield decreases due to the formation of deep trap states, which manifest themselves as a PL band in the energy range of 1.6–2.5 eV at cryogenic temperatures. A simple model explaining the behavior of the PL band as a function of temperature in the range from 30 to 300 K is proposed. [ABSTRACT FROM AUTHOR]

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]

Laser annealing was employed to trigger the solid-state reaction of a thin Co film (2.5 nm) with undoped Si. A metastable disilicide layer was obtained after one laser pulse close to the melt threshold. Its diffraction pattern, relaxed lattice parameter, and residual resisitivity are consistent with the formation of the defective CsCl structure. The CoSi2 phase was found after prolonging the thermal treatment with additional pulses or rapid thermal annealing. Because CoSi is skipped in the phase sequence, CoSi2 layers are more uniform in thickness, have an increased superconductivity and a reduced formation temperature. This approach is compatible with the SALICIDE process and can be used to form smooth contacts in superconducting or regular transistors. [ABSTRACT FROM AUTHOR]

The pyrite phase of sodium superoxide, NaO 2 , is studied using equilibrium molecular dynamics simulations and lattice dynamics calculations to understand the impacts of static disorder and dynamic disorder on its thermal conductivity. Three structural regimes are observed based on the rotational dynamics and orientations of O 2 − ions. At low temperatures, where the O 2 − ions librate and the system is fully ordered, thermal conductivity exhibits a crystal-like temperature dependence, decreasing with increasing temperature. As temperature increases, the static disorder regime emerges, where the O 2 − ions transition between different orientations on a time scale larger than the librational period. In this regime, the thermal conductivity continues to decrease and then becomes temperature independent. At higher temperatures, where the O 2 − ions freely rotate, the system is dynamically disordered and the thermal conductivity is temperature independent, as in an amorphous solid. Using instantaneous normal mode analysis and Allen–Feldman theory, 80% of the thermal conductivity in the dynamic disorder regime is attributed to diffusons, vibrational modes that are non-propagating and non-localized. When increasing the lattice constant at a constant temperature, transitions from librations to static disorder to dynamic disorder are also observed, with the thermal conductivity decreasing monotonically. The presented methodology can be applied to other crystals with rotational degrees of freedom, offering strategies for the design of thermal conductivity switches that are responsive to external stimuli. [ABSTRACT FROM AUTHOR]

Recent developments in materials manufacturing has allowed researchers to engineer unique wave-matter interactions at the nano-scale. These interactions foster unique and coupled modes of thermal, optical, electrical, and acoustic energy transport and conversion. This study addresses the sensitivity of the static ϵ 0 and complex ϵ ~ (ω) = ϵ 1 (ω) + i ϵ 2 (ω) dielectric constant due to changes in pressure (P), volume (V), and temperature (T). General β -sensistivity relations are derived based on traditional Drude and Lorentz oscillator models. Then, these sensitivity relations are compared to literature d ln ⁡ ϵ i / d T and d ln ⁡ ϵ i / d ln ⁡ V data for various metals, dielectric insulators, and semiconductor materials. For example, the effects of isotropic strain on ϵ (ω) are found to have two common contributions: the frequency dependence of the dielectric dispersion (d ln ⁡ ϵ / d ln ⁡ ω) and key vibrational-mode Grüneisen parameters (γ i = − d ln ⁡ ω i / d ln ⁡ V). Because these sensitivity relations are dictated by the various electronic, optical, and lattice Grüneisen parameters, a comprehensive listing of mode Grüneisen parameters and coupled property data are provided for materials ranging from metals to semiconductors to polymers to dielectric insulators such as BaTiO 3. In most cases, the developed sensitivity relations are consistent with published isotropic strain derivative data. [ABSTRACT FROM AUTHOR]

The pyrite phase of sodium superoxide, NaO 2 , is studied using equilibrium molecular dynamics simulations and lattice dynamics calculations to understand the impacts of static disorder and dynamic disorder on its thermal conductivity. Three structural regimes are observed based on the rotational dynamics and orientations of O 2 − ions. At low temperatures, where the O 2 − ions librate and the system is fully ordered, thermal conductivity exhibits a crystal-like temperature dependence, decreasing with increasing temperature. As temperature increases, the static disorder regime emerges, where the O 2 − ions transition between different orientations on a time scale larger than the librational period. In this regime, the thermal conductivity continues to decrease and then becomes temperature independent. At higher temperatures, where the O 2 − ions freely rotate, the system is dynamically disordered and the thermal conductivity is temperature independent, as in an amorphous solid. Using instantaneous normal mode analysis and Allen–Feldman theory, 80% of the thermal conductivity in the dynamic disorder regime is attributed to diffusons, vibrational modes that are non-propagating and non-localized. When increasing the lattice constant at a constant temperature, transitions from librations to static disorder to dynamic disorder are also observed, with the thermal conductivity decreasing monotonically. The presented methodology can be applied to other crystals with rotational degrees of freedom, offering strategies for the design of thermal conductivity switches that are responsive to external stimuli. [ABSTRACT FROM AUTHOR]

This work reports heavy ion-irradiation effects in polycrystalline Fe3O4. For this matter, Fe/Fe3O4 heterostructures were irradiated in situ in a transmission electron microscopy with 1 MeV Kr ions at 50 K. Evidence of cubic to monoclinic transformation (a.k.a Verwey transition) was recorded in some magnetite grains upon cooling the sample (around 90 K); however, most of the oxide grains retain their cubic spinel structure. Irradiation effects were analyzed in the cubic phase up to a maximum dose of 38 dpa without the sign of amorphization. The extinction of first-order reflections was recorded at doses below 1 dpa, indicating the formation of a new (metastable) phase with half of the lattice parameters compared to the unirradiated Fe3O4 crystal. The formation of the new crystalline phase, which also presents a high resistance to amorphization, is related to the disordering of the cation lattice and the high mobility of the cation interstitials. The metastable phase readily recovers around 225 K during the natural warming of the sample from 50 K to room temperature. [ABSTRACT FROM AUTHOR]

In this numerical study, we propose dual-modulated topological pillared phononic crystal (PnC) plates and demonstrate their application in achieving frequency-selective waveguiding of Lamb-wave valley-edge states. We show that both the radius and the height of the pillars in the honeycomb unit cell can be varied, allowing a generalized parameter space to obtain the complete topological bandgaps and two groups of distinct valley Hall phases for designing topological waveguides operating in different frequency ranges. Accordingly, we construct different types of phase domain walls to support valley-edge states using the dual-modulated PnC plates with a lattice constant of 2000 μm and with topological bandgaps opened around the Dirac cone frequency of 426 kHz. The numerical results show that the valley-edge states emerge to cover different frequency ranges and exhibit robust backscattering immunity when propagating along zigzag paths with sharp corners. Furthermore, the transport path of the valley-edge states can be designed to be highly dependent on the operating frequency in different domain walls. Consequently, we design a straight waveguide and three multichannel waveguides to demonstrate frequency-dependent switchable transmission and selective channeling of valley-edge states, respectively. The results of this study pave the way for the development and optimization of topological acoustic circuits using the generalized parameter space approaches and are expected to find promising applications in frequency-controlled and signal-division devices. [ABSTRACT FROM AUTHOR]

In this work, we derive the analytical expression of Helmholtz free energy, mean nearest neighbor distance between two atoms, lattice constant, and molar volume using statistical moment method (SMM). Then, we present how to determine the melting temperature of cubic perovskite at high pressures by combining SMM and work-heat equivalence principle. The results of the melting theory of cubic perovskite are applied to two perovskites MgSiO 3 and CaSiO 3 under extreme conditions of the Earth's lower mantle. Our obtained melting curves of MgSiO 3 up to 1400 GPa and CaSiO 3 up to 136 GPa were compared with available experiment and other calculations and were in good agreement. The present study provides an effective theoretical tool for finding the melting curves of strongly anharmonic materials under extreme conditions. Our theoretical calculations would be helpful to clarify geological formation process at the Earth's lower mantle. [ABSTRACT FROM AUTHOR]

We investigated the structure of ice under nanoporous confinement in periodic mesoporous organosilicas (PMOs) with different organic functionalities and pore diameters between 3.4 and 4.9 nm. X-ray scattering measurements of the system were performed at temperatures between 290 and 150 K. We report the emergence of ice I with both hexagonal and cubic characteristics in different porous materials, as well as an alteration of the lattice parameters when compared to bulk ice. This effect is dependent on the pore diameter and the surface chemistry of the respective PMO. Investigations regarding the orientation of hexagonal ice crystals relative to the pore wall using x-ray cross correlation analysis reveal one or more discrete preferred orientation in most of the samples. For a pore diameter of around 3.8 nm, stronger correlation peaks are present in more hydrophilically functionalized pores and seem to be connected to stronger shifts in the lattice parameters. [ABSTRACT FROM AUTHOR]

Magnetic structure factor (MSF), calculated from ground state configuration previously obtained by Monte Carlo simulation in different rectangular artificial spin ices, is employed to investigate ground state degeneracy. Our analysis considers the importance of nanoislands size to the ratio between rectangle sides in the lattice parameters via a dumbbell model. Pinch points in MSF along with residual entropy, determined for a number of different rectangular lattices with disconnected nanoislands, point out the conditions for the emergency of a gauge field, through which magnetic monopoles interact effectively. [ABSTRACT FROM AUTHOR]

We find that the unit cell volume (V), which affects many properties, decreases too rapidly with strain when calculated with standard density functional theories (DFTs) such as local density approximation (LDA). We find that this demerit is moderated with the use of the Hubbard potential U for local electron correlation (DFT + U). However, the introduction of U to standard DFTs, e.g., LDA and Perdew–Burke–Ernzerhof functional (PBE) optimized for solids (PBEsol), leads to the excessive underestimation of the spontaneous polarization (PS) and frequently extinguishes PS. Therefore, we attempt to improve the overall accuracy of DFTs for ferroelectrics by using U in several DFT methods including PBE that overestimates PS and lattice constants. We demonstrate that PBE with U (PBE + U) is in excellent agreement with the experimental properties of BaTiO3 and SrTiO3, with improvements in the estimates of lattice constants, PS, the phonon frequency, the antiferrodistortive angle of 105 K-phase SrTiO3, the bandgap, the strain dependence of V, and hole polarons. When the lattice parameters and PS moderately agree with the experimental data, PBE + U with a single U set can produce both electron and hole polarons. Hence, PBE + U can be a practical substitute of hybrid functionals for perovskite oxide ferroelectrics, except for the estimation of the bandgap. Furthermore, we propose an approach to construct a functional accurately depicting the incipient ferroelectric state of SrTiO3. Additionally, these results suggest that conventional DFT underestimates PS under compressive in-plane strain and predicts the unrealistic deformation of ferroelectrics and that in-plane-strained lattices can mitigate the problems associated with U. [ABSTRACT FROM AUTHOR]

Hyperbolic metasurfaces exhibit unique dispersion and polarization properties, making them a promising platform for a plethora of photonic applications. At the same time, the ability to engineer the hyperbolicity via the predefined spectral positions of the metasurface resonances remains a notable challenge. Here, we analyze the dependencies of the spectral positions of the resonances corresponding to the limits of the hyperbolic regime for the metasurfaces based on square arrays of the rectangular nanopatches. We show that the spectral difference between the resonances increases linearly with stretching of the nanopatch, but this dependence becomes quadratic when the length of the stretched nanopatch exceeds 85% of the lattice constant, indicating the regime of extreme anisotropy. Finally, we demonstrate the characteristic feature of the engineered resonances by showing the canalization (divergenceless propagation) of the surface plasmon-polariton along the anisotropic nanopatch-based metasurface in the vicinity of the resonance. The results obtained may be used for the engineering of the anisotropic nanoparticle-based metasurfaces for a plethora of photonic applications. [ABSTRACT FROM AUTHOR]

In multicomponent lattice problems, for example, in alloys and at crystalline surfaces and interfaces, atomic arrangements exhibit spatial correlations that dictate the kinetic and thermodynamic phase behavior. These correlations emerge from interparticle interactions and are frequently reported in terms of the short-range order (SRO) parameter. Expressed usually in terms of pair distributions and other cluster probabilities, the SRO parameter gives the likelihood of finding atoms/molecules of a particular type in the vicinity of other atoms. This study focuses on fundamental constraints involving the SRO parameters that are imposed by the underlying lattice topology. Using a data-driven approach, we uncover the interrelationships between different SRO parameters (e.g., pairs, triplets, and quadruplets) on a lattice. The main finding is that while some SRO parameters are independent, the remaining are collinear, i.e., the latter are dictated by the independent ones through linear relationships. A kinetic and thermodynamic modeling framework based on these constraints is introduced. [ABSTRACT FROM AUTHOR]

Spin–orbit coupling induces a current density in the ground state, which consequently requires a generalization for meta-generalized gradient approximations. That is, the exchange–correlation energy has to be constructed as an explicit functional of the current density, and a generalized kinetic energy density has to be formed to satisfy theoretical constraints. Herein, we generalize our previously presented formalism of spin–orbit current density functional theory [Holzer et al., J. Chem. Phys. 157, 204102 (2022)] to non-magnetic and magnetic periodic systems of arbitrary dimension. In addition to the ground-state exchange–correlation potential, analytical derivatives such as geometry gradients and stress tensors are implemented. The importance of the current density is assessed for band gaps, lattice constants, magnetic transitions, and Rashba splittings. In the latter, the impact of the current density may be larger than the deviation between different density functional approximations. [ABSTRACT FROM AUTHOR]

Emerging quantum materials as well as novel traditional electronic and photonic materials may enable a new generation of information science devices if they can be synthesized on suitable substrates. Additionally, material and device designs may benefit from tunable properties through engineered epitaxial strain for the manipulation of the electronic character. In this work, three series of III–V ternary alloys, GaInSb, AlInSb, and InAsSb, are grown via molecular beam epitaxy on GaAs (001) substrates to explore the flexibility of abrupt metamorphic epitaxial layers with tunable lattice parameters between 6.135 and 6.479 Å. Their deposition on both homomorphic GaAs and pseudomorphic AlAs buffers is also explored. The structures of these alloys are characterized via reflection high-energy electron diffraction, high-resolution x-ray diffraction, atomic force microscopy, and transmission electron microscopy to assess their suitability as stable buffer layers with wide variability of accessible lattice parameters. [ABSTRACT FROM AUTHOR]

Molecular dynamics and density functional theory simulations are used to predict the lattice and electronic contributions of thermophysical properties for UN, PuN, and mixed (U,Pu)N systems. The properties predicted include the lattice parameter, linear thermal expansion, enthalpy, and specific heat capacity, as a function of temperature. The simulation predictions for high temperature specific heat capacity are compared against experimental measurements to understand the behavior, and why differences in the experimental measurements are observed. The influence of adding U vacancies, N interstitials, and Pu to UN is also examined. For this, a new PuN potential parameter set is developed and used with the Kocevski UN potential, enabling the dynamics of mixed (U,Pu)N systems to be studied. How defects impact the thermophysical properties is important for understanding fuel behavior under different reactor conditions, and these mechanistic predictions can be used to support fuel performance codes where data is scarce. [ABSTRACT FROM AUTHOR]

This work outlines conditions suitable for the heteroepitaxial growth of Cr2O3(0001) films (1.5–20 nm thick) on a Ru(0001)-terminated substrate. Optimized growth is achieved by sputter deposition of Cr within a 4 mTorr Ar/O2 20% ambient at Ru temperatures ranging from 450 to 600 °C. The Cr2O3 film adopts a 30° rotated honeycomb configuration with respect to the underlying Ru(0001) substrate and exhibits a hexagonal lattice parameter consistent with that for bulk Cr2O3(0001). Heating to 700 °C within the same environment during film preparation leads to Ru oxidation. Exposure to temperatures at or above 400 °C in a vacuum, Ar, or Ar/H2 3% leads to chromia film degradation characterized by increased Ru 3d XPS intensity coupled with concomitant Cr 2p and O 1s peak attenuations when compared to data collected from unannealed films. An ill-defined but hexagonally well-ordered RuxCryOz surface structure is noted after heating the film in this manner. Heating within a wet Ar/H2 3% environment preserves the Cr2O3(0001)/Ru(0001) heterolayer structure to temperatures of at least 950 °C. Heating an Ru–Cr2O3–Ru heterostacked film to 950 °C within this environment is shown by cross-sectional scanning/transmission electron microscopy (S/TEM) to provide clear evidence of retained epitaxial bicrystalline oxide interlayer structure, interlayer immiscibility, and epitaxial registry between the top and bottom Ru layers. Subtle effects marked by O enrichment and O 1s and Cr 2p shifts to increased binding energies are noted by XPS in the near-Ru regions of Cr2O3(0001)/Ru(0001) and Ru(0001)/Cr2O3(0001)/Ru(0001) films after annealing to different temperatures in different sets of environmental conditions. [ABSTRACT FROM AUTHOR]

Nonvolatile memory using intersubband transitions and quantum-well electron accumulation in GaN/AlN resonant tunneling diodes (RTDs) is a promising candidate for high-speed nonvolatile memory operating on a picosecond timescale. This memory has been fabricated on sapphire(0001) substrates to date because of the high affinity between the nitride materials and the substrate. However, the fabrication of this memory on Si(111) substrates is attractive to realize hybrid integration with Si devices and nonvolatile memory and three-dimensional integration such as chip-on-wafer and wafer-on-wafer. In this study, GaN/AlN RTDs are fabricated on a Si(111) substrate using metal-organic vapor phase epitaxy. The large strain caused by the differences in the thermal expansion coefficients and lattice constants between the Si(111) substrate and nitride materials are suppressed by a growth technique based on the insertion of low-temperature-grown AlGaN and thin AlN layers. The GaN/AlN RTDs fabricated on Si(111) substrates show clear GaN/AlN heterointerfaces and a high ON/OFF ratio of >220, which are equivalent to those for devices fabricated on sapphire(0001) substrates. However, the nonvolatile memory characteristics fluctuate by repeated write/erase memory operations. Evaluation of the ON/OFF switching time and endurance characteristics indicates that the instability of the nonvolatile memory characteristics is caused by electron leakage through deep levels in the quantum-well structure. Possible methods for suppressing this are discussed with an aim of realizing high-speed and high-endurance nonvolatile memory. [ABSTRACT FROM AUTHOR]

Sc0.18Al0.82N/GaN with state-of-the-art x-ray diffraction figures of merit grown by metal modulated epitaxy under metal-rich conditions and a low substrate temperature of 400 °C is demonstrated to have improved crystalline order [250 arc sec for the (0002) reflection and 469 arc sec for the (10 1 ¯ 5)] compared to a previous state-of-the-art sample grown at a more conventional temperature of 650 °C. While both samples show a columnar structure, the higher substrate temperature sample has a good symmetric rocking curve (RC) of 229 arc sec, but unlike the lower temperature sample, the RC of the (10 1 ¯ 5) asymmetric reflection could not be measured, indicating a more columnar structure common among ScAlN films. Local lattice constant maps (LLCMs) from 4D-STEM depict abrupt strain relaxation within ∼2 nm from the ScAlN/GaN interface for the sample grown at Tsub = 400 °C. Since these LLCMs suggest a lattice mismatch in the a-lattice constant, and since the films show a sudden roughening, the composition for lattice match to GaN may be less than the accepted 18%–20% Sc, consistent with the average GaN lattice match from lattice constant values reported in the literature of 12%. Compared to traditional III-Nitrides, ScAlN films have substantially more screw and mixed-type threading dislocations, suggesting substantial shear forces that result in significant twist and distortion leading to orthorhombic diffraction patterns as viewed from plan-view TEM in the Tsub = 650 °C sample. These results offer the possibility of ScAlN integration into low-thermal-budget processes including CMOS but further indicate that structural understanding of ScAlN remains lacking. [ABSTRACT FROM AUTHOR]

The electronic structures of three highly mismatched alloys (HMAs)—GeC(Sn), Ga(In)NAs, and BGa(In)As—were studied using density functional theory with HSE06 hybrid functionals, with an emphasis on the local environment near the mismatched, highly electronegative atom (B, C, and N). These alloys are known for their counterintuitive reduction in the bandgap when adding the smaller atom, due to a band anticrossing (BAC) or splitting of the conduction band. Surprisingly, the existence of band splitting was found to be completely unrelated to the local displacement of the lattice ions near the mismatched atom. Furthermore, in BGaAs, the reduction in the bandgap due to BAC was weaker than the increase due to the lattice constant, which has not been observed among other HMAs but may explain differences among experimental reports. While local distortion in GeC and GaNAs was not the cause for BAC, it was found to enhance the bandgap reduction due to BAC. This work also found that mere contrast in electronegativity between neighboring atoms does not induce BAC. In fact, surrounding the electronegative atom with elements of even smaller electronegativity than the host (e.g., Sn or In) consistently decreased or even eliminated BAC. For a fixed composition, moving Sn toward C and In toward either N or B was always energetically favorable and increased the bandgap, consistent with experimental annealing results. Such rearrangement also delocalized the conduction band wavefunctions near the mismatched atom to resemble the original host states in unperturbed Ge or GaAs, causing the BAC to progressively weaken. These collective results were consistent whether the mismatched atom was a cation (N), anion (B), or fully covalent (C), varying only with the magnitude of its electronegativity, with B having the least effect. The effects can be explained by charge screening of the mismatched atom's deep electrostatic potential. Together, these results help explain differences in the bandgap and other properties reported for HMAs from different groups and provide insight into the creation of materials with designer properties. [ABSTRACT FROM AUTHOR]

We explore piezooptic and photoelastic properties of Ca3Ga2Ge4O14 (CGG) crystals. A Mach–Zehnder interferometry technique is utilized to determine a complete set of the piezooptic tensor constants πim, with particular attention to the measurement accuracy, reliability, and uncertainty resolution in the piezooptic measurements. For these reasons, independent piezooptic constants or their combinations were determined by performing interferometric measurements for different geometries of piezooptic coupling using samples of both principal (direct) and non-principal (X/45°) crystallographic cuts. Basing on the results of piezooptic measurements, a complete set of photoelastic tensor constants pim and the acousto-optic performance (figure of merit M2) of CGG crystals were evaluated. The obtained piezooptic, photoelastic, and acousto-optic characteristics of CGG crystals are compared with those of other crystals of the langasite group, langasite and CTGS (Ca3TaGa3Si2O14). A comparative analysis reveals a correlation between the values of the piezooptic or photoelastic constants and the lattice parameters for this group of crystals. High optical quality and optical transparency in the UV region of the spectrum up to 260 nm together with extremely high mechanical resistance to uniaxial compression (≤2000 kg/cm2) opens up the possibility for specific application of CGG crystal as an optical material for piezooptic sensors of high uniaxial compression. The presented piezooptic interference technique along with methodological and metrological approaches paves the way for accurate and unambiguous characterization of photoelastic crystal materials of trigonal symmetry. [ABSTRACT FROM AUTHOR]

Thermal transport in wurtzite aluminum nitride (w-AlN) significantly affects the performance and reliability of corresponding electronic devices, particularly when lattice strains inevitably impact the thermal properties of w-AlN in practical applications. To accurately model the thermal properties of w-AlN with high efficiency, we develop a machine learning interatomic potential based on the atomic cluster expansion (ACE) framework. The predictive power of the ACE potential against density functional theory (DFT) is demonstrated across a broad range of properties of w-AlN, including ground-state lattice parameters, specific heat capacity, coefficients of thermal expansion, bulk modulus, and harmonic phonon dispersions. Validation of lattice thermal conductivity is further carried out by comparing the ACE-predicted values to the DFT calculations and experiments, exhibiting the overall capability of our ACE potential in sufficiently describing anharmonic phonon interactions. As a practical application, we perform a lattice dynamics analysis using the potential to unravel the effects of biaxial strains on thermal conductivity and phonon properties of w-AlN, which is identified as a significant tuning factor for near-junction thermal design of w-AlN-based electronics. [ABSTRACT FROM AUTHOR]

Alloying and site ordering play complementary roles in dictating a material's properties. However, deconvolving the impacts of these separate phenomena can be challenging. In this work, we simulate structures of Zn (Sn , Ge) N 2 with varied Sn content and site ordering to determine the impacts of order and composition on structural and electronic properties. We assess the formation enthalpy, lattice parameters, elastic constants, spontaneous polarization, and piezoelectric coefficients. In mostly disordered structures (order parameters ranging from 0.2 to 0.4), the formation enthalpy exhibits local extrema as a function of the order parameter, deviating from the more linear trends seen in both fully disordered and fully ordered systems. This anomalous deviation from the otherwise linear trend in formation enthalpy with order manifests in each of the other properties calculated. This range of order parameters of interest may be caused by a transition in the ordering of the quaternary material similar to phase changes seen in ternary compounds but stretched over a region inclduing 20% of the order parameter range. Most parameters calculated are more sensitive to order than to composition in the limited composition range tested; however, the lattice parameter c , piezoelectric coefficient e 33 , and elastic moduli C 12 , C 13 , and C 23 are more sensitive to composition. Of the properties compared, the piezoelectric coefficients are influenced most significantly by changes in both the composition and order parameter. Lattice parameters undergo the smallest changes with order and composition, but these small differences appear to impart large trends in the other properties. Better understanding the effects of disorder and group IV alloying in Zn (Sn , Ge) N 2 allows for more accurate modeling of characteristics of this material system for solid state lighting and other applications. [ABSTRACT FROM AUTHOR]

Semilocal density-functional approximations (DFAs), including the state-of-the-art SCAN functional, are plagued by the self-interaction error (SIE). While this error is explicitly defined only for one-electron systems, it has inspired the self-interaction correction method proposed by Perdew and Zunger (PZ-SIC), which has shown promise in mitigating the many-electron SIE. However, the PZ-SIC method is known for its significant numerical instability. In this study, we introduce a novel constraint that facilitates self-consistent localization of the SIC orbitals in the spirit of Edmiston–Ruedenberg orbitals [Rev. Mod. Phys. 35, 457 (1963)]. Our practical implementation within the all-electron numeric atom-centered orbitals code FHI-aims guarantees efficient and stable convergence of the self-consistent PZ-SIC equations for both molecules and solids. We further demonstrate that our PZ-SIC approach effectively mitigates the SIE in the meta-generalized gradient approximation SCAN functional, significantly improving the accuracy for ionization potentials, charge-transfer energies, and bandgaps for a diverse selection of molecules and solids. However, our PZ-SIC method does have its limitations. It cannot improve the already accurate SCAN results for properties such as cohesive energies, lattice constants, and bulk modulus in our test sets. This highlights the need for new-generation DFAs with more comprehensive applicability. [ABSTRACT FROM AUTHOR]

Diffraction-free beams with large depth-of-field have a lot of potential in the field of acoustics, such as imaging, sensing, and particle manipulation. In this study, an acoustic Bessel-like beam is produced using an axicon-sonic crystal lens. The sonic crystal is created using cylindrical glass rods arranged in a triangular shape with a centered square lattice configuration. The numerical simulation between 4 and 8 kHz indicates that the axicon-sonic crystal converts the plane acoustic wave into a Bessel-like beam. The analysis of the beam indicates that the depth of field of this beam depends on the size and periodicity (lattice parameter) of the sonic crystal. The axicon lens also displays variable focal lengths at different frequencies. A graded index layer was implemented to mitigate the reflection caused by the significant impedance mismatch. Experimental validation of acoustic Bessel-like beam formation is also reported for the working frequencies. At 8 kHz, the measured range to the 50 % on-axis intensity was 34 λ , while the focus width at the same frequency was measured to be 2 λ. The integration of three distinct design strategies—axicon shape, sonic crystal, and graded index—expands the possibilities for sound focusing applications. [ABSTRACT FROM AUTHOR]

Epitaxial (Bi, K)TiO3 films with 800- to 900-nm thicknesses were grown hydrothermally at 200 °C on SrTiO3 substrates covered with SrRuO3 layers. Perfectly (001)-oriented films grew on (100)SrTiO3 due to good lattice matching. Films on (110)SrTiO3 had mixed orientations of dominant (110) and minor (101), while three types of (111) orientations with in-plane 120° rotation were observed for the film on (111)SrTiO3. The (101) and (110) orientations of the film deposited on (110)SrTiO3 were tilted by approximately 2.6° and 1.6°, respectively, from surface normal due to the formation of a 90° domain with a twinning plane. The plane-view measurement for the film deposited on (111)SrTiO3 showed nine spots. These are explained by the presence of 15 possible spots resulting from the relaxed 90° domain combination and by overlapping. The lattice parameters of these films explain the tilting angles of these domains. These results reveal the formation of perfectly relaxed 90° domain structures for films grown on (110) and (111)SrTiO3. This differs from our previous data for tetragonal Pb(Zr,Ti)O3 films grown above TC on (110) and (111)SrTiO3 because the present films directly grow the ferroelectric films below TC without phase change. The tilting angle of the polar-axis and the volume fraction of the 90° domain can explain the piezoelectric responses of these films assuming that films have purely an up-state. This suggests that these films show almost pure up-state polarization without 180° domains, at least along surface-normal directions. These data show that these films have domain structures different from the well-known ones for the tetragonal Pb(Zr,Ti)O3 films. [ABSTRACT FROM AUTHOR]

In the process of high temperature service, the mechanical properties of cutting tools decrease sharply due to the peeling of the protective coating. However, the mechanism of such coating failure remains obscure due to the complicated interaction between atomic structure, temperature, and stress. This dynamic evolution nature demands both large system sizes and accurate description on the atomic scale, raising challenges for existing atomic scale calculation methods. Here, we developed a deep neural network (DNN) potential for Ti–N binary systems based on first-principles study datasets to achieve quantum-accurate large-scale atomic simulation. Compared with empirical interatomic potential based on the embedded-atom-method, the developed DNN-potential can accurately predict lattice constants, phonon properties, and mechanical properties under various thermodynamic conditions. Moreover, for the first time, we present the atomic evolution of the fracture behavior of large-scale rocksalt-structure (B1) TiN systems coupled with temperature and stress conditions. Our study validates that interatomic brittle fractures occur when TiN stretches beyond its tensile yield point. Such simulation of coating fracture and cutting behavior based on large-scale atoms can shed new light on understanding the microstructure and mechanical properties of coating tools under extreme operating conditions. [ABSTRACT FROM AUTHOR]

A key development toward new electronic devices integrating memory and processing capabilities could be based on the electric control of the spin texture of charge carriers in semiconductors. In that respect, GeTe has been recently recognized as a promising ferroelectric Rashba semiconductor, with giant spin splitting of the band structure, due to the inversion symmetry breaking arising from ferroelectric polarization. Here, we address the temperature dependence of the ferroelectric structure of GeTe thin films grown on Si(111). We demonstrate the hysteretic behavior of the ferroelectric domain density upon heating/cooling cycles by low energy electron microscopy. This behavior is associated with an abnormal evolution of the GeTe lattice parameter as shown by x-ray diffraction. We explain these thermomechanical phenomena by a large difference of thermal expansion coefficients between the film and the substrate and to the pinning of the GeTe/Si interface. The accumulated elastic energy by the GeTe thin film during sample cooling is released by the formation of a -nanodomains with in-plane ferroelectric polarization components. [ABSTRACT FROM AUTHOR]

Layered electrides are a unique class of materials with anionic electrons bound in interstitial regions between thin, positively charged atomic layers. While density-functional theory is the tool of choice for computational study of electrides, there has to date been no systematic comparison of density functionals or dispersion corrections for their accurate simulation. There has also been no research into the thermomechanical properties of layered electrides, with computational predictions considering only static lattices. In this work, we investigate the thermomechanical properties of five layered electrides using density-functional theory to evaluate the magnitude of thermal effects on their lattice constants and cell volumes. We also assess the accuracy of five popular dispersion corrections with both planewave and numerical atomic orbital calculations. [ABSTRACT FROM AUTHOR]

Strain-related piezoelectric polarization is detrimental to the radiative recombination efficiency for InGaN-based long wavelength micro-LEDs. In this paper, partial strain relaxation of InGaN multiple quantum wells (MQWs) on the wafer scale has been demonstrated by adopting a partially relaxed InGaN superlattice (SL) as the pseudo-substrate. Such a pseudo-substrate was obtained through an electro-chemical etching method, in which a sub-surface InGaN/InGaN superlattice was etched via threading dislocations acting as etching channels. The degree of strain relaxation in MQWs was studied by x-ray reciprocal space mapping, which shows an increase of the in-plane lattice constant with the increase of etching voltage used in fabricating the pseudo-substrate. The reduced strain in the InGaN SL pseudo-substrate was demonstrated to be transferable to InGaN MQWs grown on top of it, and the engineering of the degree of strain relaxation via porosification was achieved. The highest relaxation degree of 44.7% was achieved in the sample with the porous InGaN SL template etched under the highest etching voltage. Morphological and structural properties of partially relaxed InGaN MQWs samples were investigated with the combination of atomic force and transmission electron microscopy. The increased porosity of the InGaN SL template and the newly formed small V-pits during QW growth are suggested as possible origins for the increased strain relaxation of InGaN MQWs. [ABSTRACT FROM AUTHOR]

Rare-earth nickelates (RENiO3: RE≠La) exhibit metal–insulator transition (MIT) properties that enable potential applications, such as critical temperature resistance thermistors, optoelectronic switches, and correlated logical devices. Nevertheless, their abrupt structural distortion across MIT results in mechanical stresses and forms microcracks within the bulk RENiO3, and this irreversibly reduces their resistive change during MIT that further impedes their practical applications. Herein, we demonstrate a compositing strategy that simultaneously improves the MIT performances and mechanical strength of RENiO3 by introducing a secondary phase of perovskite oxides with similar lattice parameters and high resistivity. Despite its much higher resistivity compared to RENiO3 (e.g., RE = Sm or Pr), introducing the LaMnO3 compositing phase under high oxygen pressure surprisingly reduces the matrix resistivity. Furthermore, such a compositing process (e.g., 20% LaMnO3) also effectively improves the mechanical strength of RENiO3 by eight times. Such counterintuitive variations are attributed to the similar structure and lattice parameter between RENiO3 and the perovskite composites that modify the grain boundary. As a result, the resistive change is more abrupt across MIT owing to the reduction in the resistivity associated with the grain boundary, while the defect generation and propagation are also suppressed that improves the mechanical properties. This further pave the way to the application of bulk RENiO3 as discrete devices in correlated electronics. [ABSTRACT FROM AUTHOR]

[Display omitted] • 28 data set containing 336 data covering 4 factor level, micro and macro parameters. • Evaluated effect of 4 factor level on mechanical properties, R, d 002 , L c and O% • Clean recycling condition of rCF using RF model were predicted and optimized. • Predicted value under recovery condition agreed well with actual value. The increasing use of carbon-fiber-reinforced plastic (CFRP) has led to its post-end-of-life recycling becoming a research focus. Herein, we studied the macroscopic and microscopic characteristics of recycled carbon fiber (rCF) during CFRP pyrolysis by innovatively combining typical experiments with machine learning. We first comprehensively studied the effects of treatment time and temperature on the mechanical properties, graphitization degree, lattice parameters, and surface O content of rCF following pyrolysis and oxidation. The surface resin residue was found to largely affect the degradation of the mechanical properties of the rCF, whereas oxidation treatment effectively removes this residue and is the critical recycling condition that determines its mechanical properties. In contrast, pyrolysis affected graphitization in a more-pronounced manner. More importantly, a random forest machine-learning model (RF model) that optimizes using a particle swarm algorithm was developed based on 336 data points and used to determine the mechanical properties and microstructural parameters of rCF when treated under various pyrolysis and oxidation conditions. The constructed model was effectively used to forecast the recovery conditions for various rCF target requirements, with the predictions for different recycling conditions found to be in good agreement with the experimental data. [ABSTRACT FROM AUTHOR]

The development of novel methods in solid‐state quantum chemistry necessitates reliable reference data sets for their assessment. The most fundamental solid‐state property of interest is the crystal structure, quantified by the lattice parameters. In the last decade, several studies were conducted to assess theoretical approaches based on the agreement of calculated lattice parameters with respect to experiment as a measure. However, most of these studies used a limited number of reference systems with high symmetry. The present work offers a more comprehensive reference benchmark denoted as Sol337LC, which consists of 337 inorganic compounds with 553 symmetry‐inequivalent lattice parameters, representing every element of the periodic table for atomic numbers between 1 and 86, except noble gases, the radioactive elements and lanthanoids. The reference values were taken from earlier benchmarks and from measurements at very low temperature or extrapolation to 0 K. The experimental low‐temperature lattice parameters were then corrected for zero‐point energy effects via the quasi‐harmonic approximation for direct comparison with quantum‐chemical optimized structures. A selection of standard density functional approximations was assessed for their deviations from the experimental reference data. The calculations were performed with the crystal orbital program CRYSTAL23, applying optimized atom‐centered basis sets of triple‐zeta plus polarization quality. The SCAN functional family and the global hybrid functional PW1PW, augmented with the D3 dispersion correction, were found to provide closest agreement with the Sol337LC reference data. [ABSTRACT FROM AUTHOR]

High-entropy alloys (HEAs) have a great potential in hydrogen storage applications. Developing an alloy showing remarkable hydrogen sorption capacity, close to ambient temperature without activating is a significant challenge for solid-state hydrogen storage. The present investigation was conducted to develop HEAs to satisfy these requirements. Accordingly, four novel equiatomic TiVCrFeTa, TiVCrFeZr, TiVCrCoTa and TiVCrCoZr HEAs were designed, fabricated and characterized to address their capability for the hydrogen storage application. Alloy design was accomplished based on empirical relations and thermodynamic calculations in order to obtain a microstructure containing both BCC and Laves phases using elements with different affinity to hydrogen. The thermodynamic calculations through CALPHAD predicted the presence of BCC/B2 phase together with C14 and C15 Laves phases in all designed alloys which was in good agreement with experimental analyses. Studies on hydrogen storage properties revealed that all alloys, except for TiVCrFeZr, are able to absorb hydrogen at 294 K and 30 bar without any activation process at a short incubation time. The results revealed that after activation, TiVCrFeZr and TiVCrCoZr alloys containing high volume fraction of Laves phase (∼40%) displayed the highest absorption capacity, with 2.3 and 1.6 wt% of hydrogen, respectively, at 294 K and 30 bar. In addition, the PCT curves proposed formation of solid solution of hydrides in TiVCrFeTa and TiVCrCoTa alloys at room temperature, however, TiVCrFeZr and TiVCrCoZr alloys provide a plateau region illustrating typical transition during hydrogen absorption. This study is a step forward to understanding necessities for developing advanced materials for the hydrogen storage. • Microstructure and hydrogen storage properties of designed TiVCrFeTa, TiVCrFeZr, TiVCrCoTa and TiVCrCoZr HEAs were studied. • Co-containing alloys provided an active surface able to absorb hydrogen at room temperature without any thermal activation process. • Zr-containing alloys with the highest volume fraction of Laves phase (∼40%) showed high absorption kinetics. • TiVCrFeZr HEA with the highest lattice parameter and lattice distortion displayed the maximum absorption capacity of 2.3 wt%. [ABSTRACT FROM AUTHOR]

Co-precipitation method is used to prepare Mn 2 Ba 2 Gd x Fe 12-x O 22 (0.00, 0.05, 0.10, 0.15, 0.20, and 0.25) Y-type hexaferrites. X-ray diffraction patterns reviled that prepared samples have single phase. The lattice parameters of 'a' and 'c' increases from 5.87 Å to 5.89 Å and 43.50 Å to 43.68 Å with the incorporation of Gd3+ (Gadolinium), respectively. Samples crystallite sizes were in the 88.8–201 nm range. The spectrum of FTIR explains Fe-O vibrational bands, which signifies the formation of Y-type hexaferrites. The maximum quality factor 'Q' value is obtained at 2 GHz. The maximum Q value at high frequency suggests the potential uses of prepared samples for multilayered chip inductors operating at high frequencies. A reduction in the values of saturation magnetization (M s), coercivity (H c) as well as in remanence (M r) were observed in 32.0–10.2 emu/g, 19.30–5.41 emu/g, and 3084.60–1071.3 Oe range respectively. The decrement in the squareness ratio was also found in the range of 0.594–0.529. The values of squareness ratios greater than 0.5 specify that the prepared materials have a sole magnetic domain. Due to the high coercivity of the prepared materials, these could be used in devices that use high frequencies and perpendicular recording mediums. [ABSTRACT FROM AUTHOR]

In the framework of the London model, computer modeling has been carried out and the distribution of the magnetic field in a massive superconductor of the II kind has been found, taking into account changes in the inhomogeneity of the magnetic field of an irregular vortex lattice. It is shown that the line shape changes significantly depending on the vortex lattice irregularity. This change should be taken into account when interpreting experimental data on the observation of the local magnetic field, the consideration of this circumstance can change the conclusions concerning the type of vortex lattice and the parameters of the superconductor. [ABSTRACT FROM AUTHOR]

Utilizing the Cambridge Serial Total Energy Package (CASTEP), we examined various properties of the compounds Na X H 3 and K X H 3 (where X represents Tc, Ru and Rh). These properties include structural, thermodynamic, hydrogen storage, optical, mechanical, and electronic. The studied compounds exhibit stables cubic crystal structures with lattice constants between 3.53 Å and 3.77 Å. Their mechanical and thermodynamic stability is confirmed by their elastic constants, phonon dispersion, and negative formation energies. The gravimetric hydrogen storage capacities are 2.44, 2.38, 2.35, 2.16, 2.11 and 2.08 wt percent for NaTcH 3 , NaRuH 3 , NaRhH 3 , KTcH 3 , KRuH 3 and KRhH 3 , respectively. Notably, KTcH 3 has the most practical hydrogen desorption temperature of 365 K. Electronic properties reveal a consistent metallic behavior across all compounds, opening possibilities for applications beyond hydrogen storage. Their calculated optical properties, including conductivity, absorption, and refractive index, suggest that KTcH 3 may be suitable for use in optoelectronic devices and solar cells. Mechanical analysis highlights NaRuH 3 as the hardest material, based on the investigated elastic moduli. These findings underscore the potential of sodium- and potassium-based perovskite hydrides not only for hydrogen storage but also for advanced energy systems, electronics, and optics. • The properties of Na X H 3 and K X H 3 (X = Tc, Ru, Rh) are examined using DFT. • Na X H 3 and K X H 3 are found to be mechanically and thermodynamically stable. • All compounds showed stable cubic structures. • The electronic assessment showed that all hydrides are metallic. • The highest hydrogen capacity is observed in NaTcH 3 with a value of 2.44 wt%. [ABSTRACT FROM AUTHOR]

Antiferromagnetic intermetallic compound EuRhGe $_3$ 3 crystalizes in a non-centrosymmetric BaNiSn $_3$ 3 -type ($I4\, {\rm mm}$ I 4 mm ) structure. We studied its pressure-dependent crystal structure by using synchrotron powder x-ray diffraction at room temperature. Our results show a smooth contraction of the unit cell volume by applying pressure while preserving $I4\, {\rm mm}$ I 4 mm symmetry. No structural transition was observed up to 35 GPa. By the equation of state fitting analysis, the bulk modulus and its pressure derivative were determined to be 73 (1) GPa and 5.5 (2), respectively. Furthermore, similar to the isostructural EuCoGe $_3$ 3 , an anisotropic compression of a and c lattice parameters was observed. Our experimental results show a good agreement with the pressure-dependent structural evolution expected from theoretical calculations below 13 GPa. Reflecting a strong deviation from integer Eu valence, the experimental volume data appear to be smaller than those of DFT calculated values at higher pressures. [ABSTRACT FROM AUTHOR]

Hexagonal ferrites have drawn significant attention due to a broad range of telecommunication and stealth technology applications. β-Type hexagonal ferrites are rarely used in various technological applications. In the current work, Nd3+ substituted polycrystalline β-type hexagonal ferries with composition LiFe 11-x Nd x O 17 (x = 0.0–0.04, ∇ x = 0.01) were prepared using the sol-gel method. All prepared samples were sintered at 1000 °C for 4 h. The influence of Neodymium (Nd3+) on its structural, electrical, and dielectric properties was investigated. Lattice parameters (a, c) and V cell increased with varying Neodymium substitution levels. The crystallite size was measured in the range of 38–42 nm. Fourier Transform IR (Infrared) spectroscopy exposed the presence of two spectral bands at 416 to 449 cm−1 and 449 to 489 cm−1. XPS (x-ray photoelectron spectroscopy) analysis verified the presence of metal ions and their chemical states in all prepared samples. The dielectric constant, loss, tan δ, and σ ac (ac-conductivity) decreased by increasing Nd3+ content. Jonscher's power law explains the conduction mechanism of charge carriers in all fabricated samples. The influence of relaxation time and grain boundaries on the electrical characteristics of prepared nanomaterials was investigated by impedance analysis. SEM (scanning electron microscopy) confirms the successful formation of β-hexaferrite nanomaterials. A minimum reflection loss of −32.08 dB was observed at 1.5 GHz for the x = 0.04 sample. This minimum reflection loss evidenced the novelty of the research and suggested their usefulness in high-frequency microwave applications. All samples investigated in this research work are suitable for high-frequency applications, multilayer chip inductors, and EM interference shielding. [ABSTRACT FROM AUTHOR]

The crystal chemical characteristics and causes of their variations in the weakly and strongly modified by epigenetic processes dolomites of the Middle Riphean Avzyan Formation in the Bashkir meganticlinorium have been determined. The studies were accomplished by the X-ray diffraction, X-ray fluorescence, and SEM/EDS analysis methods. The Avzyan dolomites are marked by increased parameters of the crystal lattice (aav = 4.8105 Å, cav = 16.0211 Å) and reduced values of the substructural reflection (Kav = 0.66) in comparison with stoichiometric dolomites. The average content of elements is as follows: Fe(II) 4545 ppm, Mn 423 ppm, and Sr 124 ppm. Increase in parameters of the crystal lattice of the Avzyan dolomites shows direct correlation with increase in the contents of Fe and Mn, whereas values of the substructural reflection have an inverse correlation. Rocks of all studied sections include two generations of dolomite and calcite. The calcite–dolomite veinlets were formed at 260–530°C and 0.3–2.3 kbar. In dolomites of different subformations, the average value of parameters of the crystal lattice a and c decreases from the early (Kataskin subformation) to the late Avzyan (Tyul'men subformation). In the same direction, average values of the coefficient K of the dolomite structure ordering increase. Dolomites of different stratigraphic levels of the Avzyan Formation underwent intense epigenetic transformations caused by the impact of medium- and high-temperature Fe- and Mn-containing fluids on rocks. Change in the crystal chemical characteristics of the Avzyan dolomites is associated not so much with the process of regional metamorphism, as with the activity of postmagmatic (sections near the Veselovka Settlement and on the Tyul'men River) and catagenetic (sections near the Islambaevo Settlement and on the Bol'shoi Avzyan River) of fluids, which percolated along the fracture zones. [ABSTRACT FROM AUTHOR]

On the rising demand for eco‐friendly refractories, reducing the use of likely toxic magnesia‐chromium aggregates remains a challenge. Previous studies by some of the authors have proposed Cr‐free alternative compositions, although the morphology of the spinel precipitates has varied across the different suggested systems. The mechanisms involved in the formation of these distinct morphologies were unclear and, therefore, are the focus of this work. In all compositions, SEM/electron backscatter diffraction revealed cube–cube orientation relationships between matrix and precipitates, indicating that their formation is influenced by the lattice parameter misfit (δ), which was measured using synchrotron X‐ray diffraction. It could be concluded that coarser and spherical precipitates form to minimize their surface‐to‐volume ratio in compositions with high absolute δ‐values. Conversely, low‐misfit systems enable the spinel to form a 3D‐network. The potential use of this knowledge to tailor the microstructure of novel compositions was demonstrated by a small Nb2O5 addition into one of the proposed compositions. [ABSTRACT FROM AUTHOR]

This work has used thermal decomposition and high-energy grinding to fabricate ZnO nanoparticles. The grinding time (tm) for up to 120 min reduced the average crystallite size (d) from 97 nm of the initial material to ~ 28 nm. Apart from Zn and O, no impurity related to the grinding was found in the fabricated nanoparticles. X-ray diffraction and Raman scattering data showed a single phase of the fabricated samples, crystallizing in the wurtzite hexagonal structure. With decreasing d, the lattice parameters gradually increased while more Zn- and O-related defects and structural distortions were created in the ZnO host lattice, which enhanced the lattice strain. These phenomena rapidly reduced excitonic emissions, enhanced the relative intensity of visible photoluminescence, widened asymmetrically and red-shifted the Raman modes, and stimulated vibration modes at wavenumbers of 500~620 cm−1. Using the spatial correlation model, the spatial correlation length characteristic for structural disorders decreased as d reduced. In particular, the study of the photocatalytic degradation of rhodamine-B under UV-light proved that lattice defects generated by the grinding reduced the degradation efficiency. [ABSTRACT FROM AUTHOR]

The solution combustion route is used to synthesize a series of MgP2O6:Tb3+(0.5–3.5 mole %) phosphors. X-ray diffraction and Rietveld refinement analysis have verified the crystal purity (monoclinic symmetry) with space group P21/n and refined lattice parameters (a = 11.12 Å, b = 8.268 Å, and c = 9.902 Å), respectively. The excitation and emission features of the synthesized material (luminescent properties) are monitored using photoluminescence spectroscopy. The emission spectrum, recorded at excitation 215 nm, shows the most prominent emission peak at 545 nm, which is responsible for green colour emission. The CIE coordinates indicate that phosphors emit in the green light region. The synthesized material has conventional application in solid-state lighting under UV excitation (215 nm). [ABSTRACT FROM AUTHOR]

Managing the hardness, density, and residual stress of the titanium nitride (TiN) hard mask has become increasingly significant for achieving excellent selectivity in the high aspect ratio etching process. This research investigates the enhancement of hardness, density, residual stress, and etch selectivity of a TiN film during the atomic layer deposition process using varying NH3 flow rates. Additionally, the study establishes a correlation between the improvement of hard mask properties and NH3 flow rates, taking into account the film composition, crystallinity, surface roughness, interface layers, and film thickness. The effects of NH3 could be summarized into three types. High N–N and Ti–N bonds, along with increased film hardness, are achieved by elevating the NH3 flow rate. Furthermore, this adjustment promotes the growth of crystal planes with higher lattice constants and modifies the interface layer thickness between Si and TiN, directly impacting residual stress. The TiN film exhibits increased roughness and decreased uniformity. In addition, at NH3 50 SCCM, hardness, density, and residual stress improved by 81.8%, 110%, and 87.5%, respectively. The selectivity saw a significant increase of 77.7%. This study provides an analysis of the relationship between the NH3 flow rate and TiN thin film properties, which is essential for improving TiN hard mask properties in flow type reactors. [ABSTRACT FROM AUTHOR]

The crystal structure and vibrational spectra of CoFe2O4 ferrite were studied using X-ray diffraction and Raman spectroscopy over a pressure range of 0–35GPa. A structural phase transition from the cubic Fd3̄m phase to the post-spinel orthorhombic Bbmm phase occurs at a pressure of approximately 23GPa through a two-phase region. Pressure-induced changes in the structural parameters, lattice distortion, and vibrational modes of the studied ferrite were investigated in detail. Lattice parameters, bond lengths, compressibility, and bulk modulus for both the cubic and orthorhombic phases of CoFe2O4 were determined. [ABSTRACT FROM AUTHOR]

Wet-chemical co-precipitation was used to create Co0.5MgxCu0.5−xFe2O4 nano-ferrites (x = 0.0, 0.2, 0.3, and 0.4). XRD, FT-IR, HRTEM, and EDX analyses were used to confirm each sample's single-phase spinel cubic crystal structure. The crystallite size was calculated from the XRD data and determined to be between (11.1570 and 16.1457 nm), with a lattice constant between (8.359 to 8.387Å). The two absorption bands found in the FTIR data were utilized to show metal cation and oxygen bond stretching at tetrahedral and octahedral positions, as well as to calculate the elastic moduli. The elemental composition and structural behavior of every sample were examined using FE-SEM and EDS. The magnetic parameters were also estimated based on the VSM data, the contribution of magnetic anisotropy (K), and the magnetic interaction by Neel's and Y-K-type magnetism modify as the Mg2+ ion substitution increases, thus we must consider how this variation in cation distribution affects all of these factors. As per the ferromagnet theory, ions originating from the magnetic tetrahedral A and octahedral B sites engage in super-exchange interactions with one another. Anti-ferromagnetic alignment occurs as a result (MB-MA). Magnetization occurs as a result. [ABSTRACT FROM AUTHOR]

Processing–structure relationships are at the heart of materials science, and predictive tools are essential for modern technological industries insofar as structure dictates intrinsic properties; however, few theoretical models exist for cation‐ordered perovskites. In this work, a combination of data mining and solid‐state synthesis was employed to collect structural data of 1:2 ordered (triple) perovskites. Three compositions within the (Ba1 − xSrx)(Mg1/3Ta2/3)O3 system were synthesized using a conventional solid‐state mixed‐oxide method. X‐ray diffraction data showed evidence of long‐range 1:2 B‐site cation ordering for all compositions. Additional data for another 24 1:2 ordered compositions were mined from literature. Correlative models for the deviation in modified tolerance factor (Δt′) were derived for each system, and a general model which is capable of predicting the pseudocubic lattice constants of such perovskites based solely on published ionic‐radii data developed. [ABSTRACT FROM AUTHOR]