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Single crystals of a new transition metal adelite-descloizite-type structure were synthesized using a high temperature (580 °C) high-pressure hydrothermal technique. Single crystal X-ray diffraction and energy dispersive X-ray analysis (EDX) were used to investigate the structure and elemental composition, respectively. SrNi(VO4)(OH) crystallizes in an acentric orthorhombic crystal system in the space group P212121 (no. 19); Z = 4, a = 5.9952(4) Å, b = 7.5844(4) Å, c = 9.2240(5) Å. The structure is comprised of a Ni–O–V framework where Sr2+ ions reside inside the channels. Single-crystal magnetic measurements display a significant anisotropy in both temperature- and field-dependent data. The temperature dependent magnetic measurement shows antiferromagnetic behavior at TN~8 K. Overall, the magnetic properties indicate the presence of competing antiferromagnetic and ferromagnetic interactions of SrNi(VO4)(OH). [ABSTRACT FROM AUTHOR]

Mononuclear iridium(III) complexes, NBu4[IrBr4(bpym)] (1) and [IrBr3(bpym)(MeCN)] (2a and 2b) [NBu4+ = tetra(n-butyl)ammonium cation; bpym = 2,2'-bipyrimidine], have been prepared and characterized. Their crystal structures were determined by single-crystal X-ray diffraction. 1 and 2a crystallize in the monoclinic crystal system with space groups P21/c and P21/n, respectively. The 2b phase crystallizes in the orthorhombic crystal system with space group P212121. In these complexes, each iridium(III) is six-coordinate and bonded to two (1) or three (2a and 2b) nitrogen atoms from bpym and MeCN (2a and 2b) molecules and three (2a and 2b) or four (1) bromides. In all the cases, they exhibit a distorted octahedral environment. 2a and 2b display a packing polymorphism containing π···Br, C–H···Br and Br···Br intermolecular interactions. Further analyses of their crystal structures were performed through the SHAPE and CrystalExplorer programs. The electrochemical properties of 1 and 2 were investigated through cyclic voltammetry (CV) technique, with 1 showing a reversible iridium(III)–iridium(IV) redox process. [ABSTRACT FROM AUTHOR]

Heterocyclic compounds are present abundantly in nature. Nitrogen containing heterocyclic compounds are an important class which made significant contributions to medicinal chemistry. Oxadiazole derivatives are scaffolds which exhibit wide range of biological applications. The title compound was synthesized and crystallizes in the orthorhombic crystal system. The structure exhibits C–H...N intermolecular interactions. The structure is stabilized by π–π interactions between the oxadiazole and phenyl rings. Intermolecular interactions are quantified by Hirshfeld surface analysis. Energy frameworks are constructed to investigate the stability of the compound. Molecular geometry calculations are performed using density functional theory by employing 6–31 + G (d, p) functional basis set. The chemical significant sites are identified by topology analysis. The research article presents the synthesis of 2,5-bis(4-chlorophenyl)-1,3,4-oxadiazole, and single crystal XRD study to unveil the crystal parameters. Intermolecular interactions were explored by Hirshfeld surface analysis. Further, computational analysis were performed. [ABSTRACT FROM AUTHOR]

The organometallic complex [Pd(dpp-bian)(C4(COOMe)4)]·(C2H5)2O (1·(C2H5)2O) is obtained by the interaction of [Pd2(dba)3] (dba = dibenzylideneacetone) with dimethyl ether of acetylenedicarboxylic acid and 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (dpp-bian) in the 1:4:2 molar ratio. During the oxidative addition reaction the 1,2,3,4-tetrakis(methoxycarbonyl)buta-1,3-dienyl dianion is formed from two molecules of dimethyl ether of acetylenedicarboxylic acid. This dianion is coordinated to palladium(II) via 1 and 4 carbon atoms with the formation of the palladacyclopentadienyl moiety. The crystal structure is determined by the single crystal X-ray diffraction analysis. The 1·(C2H5)2O compound crystallizes in the orthorhombic crystal system (Pbca) with unit cell parameters a = 16.9069(3) Å, b = 23.5618(6) Å, c = 23.8902(7) Å, V = 9516.83(40) Å3. Each palladium atom has an almost square planar environment composed of two dpp-bian nitrogen atoms and two carbon atoms of the (C4(COOMe)4)2– anion. The cyclic voltammogram of 1 in acetonitrile reveals irreversible oxidation at Ea = 1.43 V, reversible reduction at E1/2 = 0.62 V, and irreversible reduction at Eb = 1.52 V. The electronic structure of complex 1 is studied within the density functional theory. [ABSTRACT FROM AUTHOR]

• High yield synthesis of tert -butyl (4-ethynylphenyl)carbamate. • Complete characterization by NMR, FTIR, HRMS and UV–vis. • Unequivocal assignment of 1H and 13C NMR by 2D-NMR, HMQC and HMBC. • Single crystal x-ray shown an orthorhombic crystal system P2 1 2 1 2 1. • The Grimme, Wiberg and Hirshfeld surface tools were applied. Structure and conformation of tert -butyl(4-ethynylphenyl)carbamate, the compound combining carbamate and alkyne parts within the molecule, were studied using single X-ray diffraction analysis, NMR, FTIR and UV–vis spectroscopies. For unambiguous assignment of the signals 1H and 13C-APT-NMR, HMQC and HMBC-NMR experiments were realized. The compound crystallized in orthorhombic crystal system, displaying N H O hydrogen bonds and C H-π interactions. The X-ray structure has been recreated by means of theoretical calculations in order to assess the proposed arrangement and discuss the source of the intra and intermolecular relationships. The use of Grimme, Wiberg and Hirshfeld surface tools were applied to have a good confirmation of the presence and importance of hydrogen bonds. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Crystal structure of Ba 2 Lu 5 O 2 (BO 3) 5 is refined by the Rietveld method. • The structure is described in terms of cation- and oxo-centered polyhedra. • Thermal behavior of the oxoborate is investigated over a wide range of temperatures. • Anisotropy of thermal expansion is explained based on crystal structure data. Ba 2 Lu 5 O 2 (BO 3) 5 borate was prepared using a high-temperature multi-step solid-state reaction synthesis. Its crystal structure was first refined by the Rietveld refinement using X-ray powder diffraction data (at 25 °C). It crystallizes in the orthorhombic crystal system (Pbcn) with unit cell parameters a = 17.31669(3), b = 6.55523(3), c = 12.84820(5) Å, V = 1458.463(2) Å3, Z = 4. The structure can be described as a heteropolyhedral framework composed of distorted boron- and lutetium-oxygen polyhedra. The Ba2+ atoms are in cavities of the framework. A static disorder exists in the structure due to an occupation of the M (1) and M (2) (M = Ba2+, Lu3+) sites in parallel by the Ba2+ and Lu3+ atoms. There are vertex- and edge-sharing oxo-centered [O(7) M 4 ] n+ tetrahedra in the structure that form infinite [O 2 M 5 ] n+ isolated single chains elongated through the c axis. A thermal behavior of Ba 2 Lu 5 O 2 (BO 3) 5 was investigated by high-temperature X-ray powder diffraction over the temperature range of 25–1000 °C. No phase transitions occur in the range investigated. Degree of the thermal expansion anisotropy decreases with the temperature increase (Δ max = 0.52 at 25 °C and 0.16 at 1000 °C), while the volume expansion increases (α V = 26.8 and 36.8 × 10−6 °C−1 at 25 and 1000 °C, respectively). The anisotropy of the expansion is described in comparison with the crystal structure of Ba 2 Lu 5 O 2 (BO 3) 5. [ABSTRACT FROM AUTHOR]

[Display omitted] • Good quality single crystals of tetrabromo zincate (II) piperazinium in an orthorhombic system with P2 1 2 1 2 1 were grown. • Metal–ligand coordination, structural properties and hydrogen bonds are discussed. • TBPZ crystal is thermally stable up to 305 °C. • SHG efficiency of the TBPZ is 1.5 times that of KDP crystal. Single crystals of non-centro symmetric inorganic–organic hybrid material, tetrabromozincate(II) (Piperazinium) [TBZP] have been investigated by the combined approach of the experimental and computational methods. A re-determination of crystal structure of the title compound crystal grown by slow evaporation method and the solid-state properties of the crystal was studied. Single-crystal X-ray diffraction analysis shows that the compound crystallized in the orthorhombic crystal system with non-centrosymmetric space group P2 1 2 1 2 1. The title compound structure is made up of isolated [ZnBr 4 ]2- anions and piperazinium [C 4 H 12 ]2+ cations linked together by N-H•••Br hydrogen bonds. The existence of the functional group in the produced molecule is demonstrated by the infrared spectra. The UV–Vis-NIR analysis indicates that the synthesized crystal exhibits good transparency between 230 and 1100 nm in wavelength range. The thermal properties of the formed crystal were determined using thermogravimetric measurements. The Kurtz and Perry method was used to calculate the second-order harmonic generating efficiency, which came out to be 1.5 times greater than KDP. The solid-state density functional theory computations have been adapted with the B3LYP/LanL2DZ level and extensively investigated. [ABSTRACT FROM AUTHOR]

Industrial processes involving the manufacture of heat treatment salts such as BaCl at high pressures are becoming possible. Hence, there is a need to search for a specific form of BaCl with excellent thermal properties. Motivated by this, the potential energy surface of BaCl is extensively explored using the unbiased particle swarm-intelligence optimization algorithm to uncover a global minimum enthalpy phase of BaCl within the pressure range that was recently experimentally explored. Previously predicted phases were confirmed during the structure search. Furthermore, the orthorhombic Pnma form of BaCl is predicted to be more stable and energetically more favorable than the previously predicted R-3m phase in the pressure range of ~10–15 GPa. The electronic and thermal properties of the newly discovered phase are extensively studied using first principles calculations. In the pressure range of interest, Pnma BaCl is metallic and nonmagnetic. More so, the solution of the Boltzmann Transport Equation unravels promising thermal properties, which make Pnma BaCl a good candidate for heat management in high temperature systems. We found the overall Grüneisen parameters in Pnma BaCl to range between 0.963 and 0.995 and the lattice thermal conductivity at 300K to be 53.7W m–1K–1. We also found that Pnma BaCl exhibits anisotropy that we observed is constant in all directions explored. [ABSTRACT FROM AUTHOR]

Gallium (Ga) doped silicon (Si) is becoming a relevant player in solar cell manufacturing thanks to its demonstrated low light-induced degradation, yet little is known about Ga-related recombination centers. In this paper, we study iron (Fe)-related recombination centers in as-grown, high quality, directionally solidified, monocrystalline Ga-doped Si. While no defect states could be detected by deep level transient spectroscopy, lifetime spectroscopy analysis shows that the minority carrier lifetime in as-grown wafers is dominated by low levels of FeGa related defect complexes. FeGa pairs have earlier been shown to occur in two different structural configurations. Herein, we show that in terms of recombination strength, the orthorhombic pair-configuration is dominant over the trigonal pairconfiguration for FeGa. Furthermore, the defect energy level in the band gap for the orthorhombic defect center is determined to be EVþ0.09 eV, and the capture cross-section ratio of the same defect center is determined to be 220. [ABSTRACT FROM AUTHOR]

Magnetodielectric (MD) materials have attracted considerable attention due to their intriguing physics and potential future applications. However, the intrinsicality of the MD effect is always a major concern in such materials as the MD effect may arise also due to the MR (magnetoresistance) effect. In the present case study, we report an experimental approach to analyse and separate the intrinsic and MR dominated contributions of the MD phenomenon. For this purpose, polycrystalline samples of LaGa1-xAxO3 (A = Mn/Fe) have been prepared by solid state reaction method. The purity of their structural phase (orthorhombic) has been validated by refining the X-ray diffraction data. The RTMD (room temperature MD) response has been recorded over a frequency range of 20Hz to 10MHz. In order to analyse the intrinsicality of the MD effect, FDMR (frequency dependent MR) by means of IS (impedance spectroscopy) and dc MR measurements in four probe geometry have been carried out at RT. A significant RTMD effect has been observed in selected Mn/Fe doped LaGaO3 (LGO) compositions. The mechanism of MR free/intrinsic MD effect, observed in Mn/Fe doped LGO, has been understood speculatively in terms of modified cell volume associated with the reorientation/ retransformation of spin-coupled Mn/Fe orbitals due to the application of magnetic field. The present analysis suggests that in order to justify the intrinsic/resistive origin of the MD phenomenon, FDMR measurements are more useful than measuring only dc MR or analysing the trends of magnetic field dependent change in the dielectric constant and tanδ. On the basis of the present case study, we propose that IS (FDMR) alone can be used as an effective experimental tool to detect and analyse the resistive and intrinsic parts contributing to the MD phenomenon. [ABSTRACT FROM AUTHOR]

Composition dependent Rayleigh and structural analysis was carried out on lead-free piezoceramics (1-x)Ba(Ti0.88 Sn0.12)O3-x(Ba0.7Ca0.3)TiO3 at room temperature. The system exhibits a tetragonal (P4mm) structure for x>0.21, rhombohedral (R3m) for x<0.13, and orthorhombic (Amm2) for 0.13

Composition dependent Rayleigh and structural analysis was carried out on lead-free piezoceramics (1-x)Ba(Ti0.88 Sn0.12)O3-x(Ba0.7Ca0.3)TiO3 at room temperature. The system exhibits a tetragonal (P4mm) structure for x>0.21, rhombohedral (R3m) for x<0.13, and orthorhombic (Amm2) for 0.13

The wake-up effect in yttrium doped hafnium oxide is investigated by pulse measurements, revealing the initial distribution of oxygen vacancies within symmetrical and asymmetrical layer stacks. It is shown that single pulses are sufficient to achieve a significant wake-up, whereby additional pulses lead to a stronger wake-up. Further cycling induces a degradation of the devices, which is explained by generation of oxygen vacancies and results in an electroforming step where subsequently resistive valence change mechanism switching is observed. The degradation and therefore the generation of oxygen vacancies show a strong frequency dependence, whereby the device lifetime is strongly increased for increasing frequencies. [ABSTRACT FROM AUTHOR]

The wake-up effect in yttrium doped hafnium oxide is investigated by pulse measurements, revealing the initial distribution of oxygen vacancies within symmetrical and asymmetrical layer stacks. It is shown that single pulses are sufficient to achieve a significant wake-up, whereby additional pulses lead to a stronger wake-up. Further cycling induces a degradation of the devices, which is explained by generation of oxygen vacancies and results in an electroforming step where subsequently resistive valence change mechanism switching is observed. The degradation and therefore the generation of oxygen vacancies show a strong frequency dependence, whereby the device lifetime is strongly increased for increasing frequencies. [ABSTRACT FROM AUTHOR]

We investigate the effects of Sm and La substitution in ferroelectric BiFeO3 thin films on the lattice dynamics by infrared reflection measurements at room temperature. The frequencies of the infraredactive phonon modes are studied as a function of Sm and La content in Bi1-x(Sm,La)xFeO3 composition spread films in the range from x=0 up to x=0.25, grown on SrTiO3 substrates by pulsed laser deposition. Substitution of the Bi3+ ions with small Sm3+ ions leads to the appearance of a new phase above x≈0.09 coexisting with the ferroelectric BiFeO3 phase up to x≈0.19. In contrast, for the substitution of Bi3+ ions with La3+ ions of similar size a continuous transition from the original BiFeO3 phase to a new phase takes place. In both cases, we assign the new phase to the paraelectric, orthorhombic phase. These findings are discussed in terms of the morphotropic phase boundary in Sm-doped BiFeO3 around x=0.14 with a phase coexistence, which was suggested as the origin for enhanced piezoelectric properties. [ABSTRACT FROM AUTHOR]

In this manuscript, we explore diisopropylammonium iodide (DPI) for its ferroelectric properties and phase transitions. DPI showed two phase transitions which were identified by differential scanning calorimetry and dielectric and nonlinear optical measurements. From detailed structural studies it was found that the first transition at 369K is from orthorhombic P212121 to monoclinic P21. The polar P21 phase is ferroelectric as evidenced by the pyroelectric data and has a very high value of spontaneous polarization (Ps=33 µC cm-2), which is probably the highest among other reported bulk organic ferroelectrics. The second transition at 415K is identified as polar monoclinic P21 space group to non-polar monoclinic P21/m. Thus, DPI has a high Curie temperature of 415 K. The large spontaneous polarization and high Curie temperature make DPI technologically important. [ABSTRACT FROM AUTHOR]

High-Temperature Superconductors Bi 1. 6 Pb 0. 4 Sr 2 Ca 2 Cu 3 O 10 + δ samples doped with Sm 2 O 3 nanoparticles in different quantities (0.00, 0.02, 0.04 and 0.06), were synthesised. Solid state feedback technique was used to prepare the samples and then characterised. The morphology and structure of the specimens were deployed by scanning electron microscopy (SEM) and X-ray diffraction (XRD) examination. The spectroscopy of the energy dispersive X-ray (EDX) experiment was utilised to obtain the elemental composition of the samples. Resistivity versus temperature measurement in DC mode was employed to estimate the critical transition temperature of each sample. XRD with the Rietveld refinement process revealed that Bi2223 and Bi2212 stages exist mutually in specimens with orthorhombic crystal systems. The lowest percentage of volume fraction associated with the Bi2223 phase belonged to the sample with x = 0. 06 nanoparticle samarium doped. It was detected that with rising samarium content the volume division of the Bi2223 phase decreases but the Bi2212 stage increases compared with the pristine specimen. SEM showed that the shrinkage of grain size occurs when the amount of nano-sized Sm was added to x = 0. 02 sample with lower inter-coupling among superconducting granules. This effect might be verified by SEM and TEM images. EDX exhibited some peaks related to Sm and other elements of the Bi2223 structure. These patterns confirm that all elements associated with the compounds were introduced into the Bi2223 matrix. The critical temperatures such as T c o n s e t , T c P e a k and T c z e r o decreased for Sm doped samples compared with the pure sample. Adding Sm 2 O 3 nanoparticles causes rising calculated density and hole carrier concentration. These outcomes can be interpreted as the allocation of additional positive charges to the CuO2 planes. It is worth mentioning that the superb properties such as high-Tc, high Jc, strong flux pinning, and good thermal stability, for Bi2223 and high breakdown electric field, high dielectric constant, and large bandgap for Sm2O3 are the issues to motivate the author to dope Bi2223 with Sm2O3 NPs. In brief, the electrical, mechanical and structural properties of Sm2O3 NPs doped Bi2223 play the main role in the applications, which drive the investigations to emphasise the synthesis of superconducting samples. [Display omitted] • High-temperature Bi2223 superconducting ceramics doped with Sm 2 O 3 nanoparticles were synthesised. • By inserting the Sm 2 O 3 NPs content Bi2223 phase was reduced and altered gradually to Bi2212 phase. • Dislocation density raised for x = 0. 02 add-on then decreased with the cumulative Sm substance. • T c o n s e t , T c P e a k and T c z e r o decreased with the doping of Sm 2 O 3 NPs. • By rising Sm 2 O 3 NPs hole carrier concentration, h c c increased compared to the pure sample. [ABSTRACT FROM AUTHOR]

• Single crystal XRD of PZ-PSBA crystalline salt was studied. • The Hirshfeld surface 3D visualisation was used to analyse the intermolecular interactions of PZ-PSBA. • Differential scanning calorimetry and thermogravimetric analysis (TGA-DSC) were used to investigate the thermal properties and decomposition behaviour of the crystalline salt. • DFT calculations predicted the chemical properties and reactivity of PZ-PSBA. • Antibacterial inhibitory capabilities and promising activity of PZ-PSBA against the human cervical cancer cell line was exhibited. In this investigation, the target crystalline salt was synthesized by combining 4-phenyl sulfanyl butanoic acid (PSBA) and piperazine (PZ). The process encompassed experimental methodologies, such as Powder X-ray Diffraction (PXRD),Single Crystal X-ray Diffraction (SCXRD), Nuclear Magnetic Resonance (NMR), Infrared Spectroscopy (IR),Thermogravimetric Analysis and Differential Scanning Colorimetry (TGA-DSC), as well as theoretical analyses of the synthesized compound.The crystalline salt was successfully synthesized via the solvent evaporation method at room temperature.PZ-PSBA has an orthorhombic crystal system with space group Pbca and unit cell parameters a = 7.4357(10)Å, b = 9.4853(12)Å, c = 34.299(5), and α=β=γ=90°. We employed the B3LYP functional with 6–311++ G (d, p) as a basis set to geometrically optimize the molecular structure using Density Functional Theory (DFT).The synthesized material inhibits the human colon cancer cell line HT-29, the human lung adenocarcinoma cell line A549, and the human gastric cancer cell line MKN45, with substantial biological effects that have been demonstrated to be effective. According to in vitro and in sillico anticancer studies, PZ-PSBA has better activity against the human cervical cancer cell line (HeLa) and in bioinformatics analysis. PZ-PSBA suppressed pathogenic strains better than its parent chemical and can thus be suggested for the treatment of bacterial infections. [Display omitted] [ABSTRACT FROM AUTHOR]

Picric acid (PA) – polymethyl methacrylate (PMMA) nanofibers were synthesised using electrospinning technique by optimising all the required parameters. The nonlinear optical behaviour of the synthesised nanofibers was investigated along with their preliminary characterisations like morphological, structural, thermal, mechanical, dielectric and linear optical studies. The nanofibers with average diameter around ∼800 nm, were found to crystallise in Pca2 1 space group under the orthorhombic crystal system. The incorporation of Picric acid nanocrystals inside the PMMA nanofibers enhanced their tensile strength. Second harmonic generation imaging of picric acid embedded PMMA nanofibers was done by nonlinear microscopy and the emission was confirmed by power dependence as well as Kurtz – Perry powder technique. Nonlinear absorption studies by Z – scan technique were conducted with a Q – switched Nd: YAG laser and the nanofibers exhibited reverse saturable absorption nature at all the input intensities (0.616 × 1012 W/m2, 1.23 × 1012 W/m2 and 2.46 × 1012 W/m2) and the value of the nonlinear absorption coefficient increased corresponding to an increase in input intensity (0.98 × 10−10 m/W, 1.39 × 10−10 m/W and 1.61 × 10−10 m/W) owing to a sequential two photon absorption. Using the transmittance data optical limiting properties of the nanofibers were also analysed and the limiting threshold values (1.92 × 1012 W/m2, 1.80 × 1012 W/m2 and 1.54 × 1012 W/m2) at respective intensities were extracted. The low optical limiting threshold obtained in the present case confirms that picric acid – PMMA nanofibers can be an assured contender as optical limiters in laser safety devices. • Synthesis of Picric acid (PA) - PMMA nanofibers by electrospinning technique. • Enhancement in the tensile strength of the nanofibers due to PA incorporation. • Confirmation of SHG emission by nonlinear microscopy and Kurtz Perry technique. • Z-scan technique was used to investigate its nonlinear absorption properties. • Sample showed RSA behaviour, thus can be used for optical limiting applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Crystal structure analysis reveals an orthorhombic crystal system for 1-(carboxymethyl)cyclohexyl methanaminium dihydrogenphosphate. • The presence of phosphate units enhances stability due to structural robustness, while organic components introduce flexibility and specific reactivities. • Integration of inorganic units into conjugated structures impacts electron behavior, offering potential applications in optical nonlinearity. • Hirshfeld surface analysis reveals specific interaction types within the molecules, highlighting H•••H (53.8%), O•••H (42.9%), and O•••O (2.2%) contributions. • Void volume calculations reveal a lack of substantial cavities in the crystal, with electron density exhibiting openness in regions of interspecies approaches. The investigation into the crystal structure of 1-(carboxymethyl)cyclohexyl methanaminium dihydrogenphosphate endeavors to unravel the intricate molecular interactions at play. Utilizing Hirshfeld surface analysis, we delineate the specific types of interactions within the molecules. Fingerprint plots and molecular surface contours (dnorm, di, and de) vividly illustrate the proportional contributions of H...H (53.8%), O...H (42.9%), and O...O (2.2%). Further characterization through FTIR and UV–Vis spectroscopy enhances our comprehension. In contrast, the molecular arrangement's reinforcement stems from the N H... O interaction, leading to a linear chain. Through FTIR and FT-Raman experiments, we discern functional groups, contrasting experimental results with theoretical values. Mulliken atomic charges are meticulously examined, indicating reduced reactivity and heightened stability across diverse environments. Exploration of energy gaps in HOMO-LUMO and Density of States (DOS) spectra reveals coherence, supported by Natural Bond Orbital (NBO) Analysis, accentuating the equilibrium in energy during donor and acceptor transitions. This holistic approach enriches our understanding of the structural intricacies and stability factors inherent in the examined compound. [ABSTRACT FROM AUTHOR]

In this work, the crystal structure of a natural specimen of the "Messbach-type" variscite from Tooele Co. (Utah, U.S.A.) was determined, and the dehydration process leading to the transition to a new AlPO SB 4 sb phase was monitored at high temperature. Crystal structure description of variscite 2O and comparison with variscite 1O Like variscite I 1O i , the variscite I 2O i crystal structure belongs to the family of framework 3D MT structures in which octahedra (M) and tetrahedra (T) are linked by bridging O atoms ([30]). The Al-coordination change from octahedral to tetrahedral that accompanies dehydration, clearly demonstrated by the SP 27 sp Al NMR data, confirms the removal of the Al-bound H SB 2 sb O molecules as the dehydration mechanism, transforming the variscite octahedral-tetrahedral framework to a purely tetrahedral framework. Keywords: Variscite; X-ray powder diffraction; charge-flipping; nuclear magnetic resonance; polytypism; AlPO4 EN Variscite X-ray powder diffraction charge-flipping nuclear magnetic resonance polytypism AlPO4 1385 1395 11 07/05/22 20220701 NES 220701 Introduction Interest in hydrated aluminophosphates and in compounds that derive from their dehydration spans a wide spectrum of disciplines. [Extracted from the article]

We report the synthesis of single-crystals of a new transition metal-containing quaternary chalcogenide, Ba4Mn2Si2Te9, synthesized by the solid-state method at 1273 K. A single-crystal X-ray diffraction study shows that it crystallizes in the orthorhombic crystal system (space group: Pbam) with cell constants of a = 13.4690(6) Å, b = 8.7223(4) Å, and c = 10.0032(4) Å. The asymmetric unit of the structure consists of eight unique crystallographic sites: one Ba, two Mn, one Si, and four Te sites. In this structure, the two Mn sites, Mn(1) and Mn(2), are disordered, each with fractional occupancy of 50%. The short distance of 2.170(3) Å between Mn(1) and Mn(2) implies that both Mn sites are not occupied simultaneously. The Mn atoms show two types of polyhedra: unique Mn(1)Te5 units along with traditional Mn(2)Te4 tetrahedra. The main motifs of the Ba4Mn2Si2Te9 structure are dimeric Si2Te6 units (with Si–Si single bond), Mn(1)Te5, and Mn(2)Te4 polyhedra. The structure can be described as pseudo-two-dimensional if only Mn(1) atoms are present and one-dimensional when only Mn(2) atoms are filled in the structure. The extended 2∞ [Mn(1)Si2Te9]10− layers and 1∞ [Mn(2)Si2Te8]8− chains are separated by Ba2+ cations. The direct bandgap for the polycrystalline Ba4Mn2Si2Te9 sample is 0.6(1) eV, as determined from an optical absorption study consistent with the sample's black color. The resistivity study of the polycrystalline Ba4Mn2Si2Te9 also confirms the semiconducting behavior. The thermal conductivity (κ) values are extremely low and decrease with increasing temperature up to 0.46 W m−1 K−1 at 773 K. The DFT studies suggest that the computed bandgap depends on the magnetic ordering of Mn magnetic moments, and the value varies from ∼0.3–1.0 eV. Relative inter-atomic bond strengths of pertinent atom pairs have been analyzed using the crystal orbital Hamilton populations (COHP). [ABSTRACT FROM AUTHOR]

Novel NaAGeO 4 (A = Sm, Y) ceramics with olivine structures were prepared and characterized. The phase composition, microstructural evolution, and densification behavior of the ceramics were investigated. The NaAGeO 4 (A = Sm, Y) ceramics possessed a single orthorhombic crystal system with Pbn21 and Pnma space groups. The NaSmGeO 4 ceramics had dense grains, clear boundaries, and low sintering temperatures, whereas a relatively wide range of sintering temperatures were feasible for the NaYGeO 4 ceramics. The NaSmGeO 4 ceramic material sintered at 1025 °C possessed excellent performance-related parameters, i.e., Q × f = 31,281 GHz, ε r = 6.29, and τ ƒ = −48.3 ppm/°C, whereas those for the NaYGeO 4 ceramic material were Q × f = 32,646 GHz, ε r = 6.74, and τ ƒ = −39 ppm/°C at 1200 °C. Furthermore, doping the NaYGeO 4 ceramic material with CaTiO 3 to obtain 0.12CaTiO 3 -0.88NaYGeO 4 yielded a τ ƒ value close to zero (−3 ppm/°C). The results demonstrate that NaAGeO 4 (A = Sm, Y) ceramics have substantial potential for application in microwave devices. [ABSTRACT FROM AUTHOR]

This study aims to synthesis 2-[(dipyrrolidin-1-yl)methylene] malononitrile 2 and identify its crystal structure by X-ray diffraction analysis. 2-[(dipyrrolidin-1-yl)methylene] malononitrile was prepared by a direct displacement of the methylthio group (SMe) in the 2-[bis(methylthio)methylene] malononitrile 1 with pyrrolidine as cyclic secondary amine by conjugating addition-elimination reaction under reflux conditions for two hours. The compound was obtained in high yield (80%). The structure of compound 2-[(dipyrrolidin-1-yl)methylene] malononitrile2 was identified by performing X-ray diffraction analysis. Suitable crystals of compound 2 were grown by slow evaporation of methanol solution of the compound. The compound 2 crystallized in an orthorhombic crystal system with a space group of Pbcn. In the title compound, the two cyanide groups and the two pyrrolidine rings adopted trans configurations across the C2=C3 bond. The bond lengths and angles of the two pyrrolidinyl rings in the compound are within the normal range. The maximum deviation of N5/C2/C3/C4/N5a/C4a is 0.002(1) around C4, and no deviation has been recorded for the fragment N1/N1a/C2/C3 (0.000 (1)°). The dihedral angle between the pyrrolidine ring and N1/N1a/C2/C3 is 33.06(8)°, and the dihedral angle between the pyrrolidine ring and N5/C2/C3/C4/N5a/C4a is 50.57(7)°. The crystal packing is stabilized by two intermolecular and one intramolecular C---H…N hydrogen bonds, which form a one-dimensional polymeric chain along the axis.

In the present work, we report on the synthesis of EuSO4 powders by two different methods using EuS as starting material. The compound EuSO4 contains divalent europium and crystallizes in the orthorhombic crystal system, space group Pnma with parameters close to SrSO4. The compound exhibits near isotropic thermal expansion over the temperature range 300–700 K. EuSO4 was examined by Raman, Fourier‐transform infrared absorption and luminescence spectroscopy methods. EuSO4 is found to be an indirect bandgap material with a bandgap close to direct electronic transition. The emission lifetime of divalent europium d‐f emission in EuSO4 shows an unusual behavior for stoichiometric compounds, as it shortens upon cooling from 1.11(1) μs at room temperature to 0.44(1) μs at 77 K. [ABSTRACT FROM AUTHOR]

A novel organometallic single crystal of Bis(15-Crown-5-k5O) barium tetrakis (isothiocynato-kN) cobalt (II) [BCBCTC] was synthesized by slow evaporation solution growth technique at ambient temperature. The grown title compound has been harvested with a dimension of 8 × 5 × 2 mm3 during a period of 10–15 days. The lattice cell parameters, crystal symmetry, and structure were investigated by single-crystal X-ray diffraction technique. Additionally, the different facets of various crystal planes were indexed by powder X-ray diffraction patterns. The result reveals that the title compound belongs to orthorhombic crystal system with a space group of Pnma. The spectroscopic properties of grown crystal were analyzed by FTIR, micro-Raman, and UV–optical spectra. From the UV–optical absorbance spectrum was clearly shown that the cut-off wavelength of the BCBCTC is ~ 369 nm, and optical bandgap is ~ 3.36 eV found to be Tauc's relation. Moreover, the grown crystal surface morphology, reverse growth rate, and presence of chemical compositions were further verified by FE-SEM, EDAX, and etching studies. The thermal stability and mechanical property were calculated by TG-DSC and Vickers's hardness tester. The various dielectric properties such as dielectric constant (εr) and dielectric loss (tan δ) of the grown title compound were studied at a function of temperature, and results are discussed. Furthermore, the linear and nonlinear coefficients such as nonlinear refractive index (n2), nonlinear absorption (β), third-order susceptibility (χ3), and then hyper polarizability (γ) were measured by Z-Scan studies. [ABSTRACT FROM AUTHOR]

Single crystals of 3-hydroxypyridinium 2,4-dinitrophenolate (I) and 4-hydroxypyridinium 2,4-dinitrophenolate (II) was harvested under slow evaporation conditions. The yellow block crystals formed by O–H⋯O and N–H⋯O hydrogen bonding that made contacts through the cation and anion was characterized by single-crystal X-ray diffraction, infrared spectrum, diffuse reflectance spectrum, thermogravimetric and Hirshfeld surface analysis. Crystal (I) packed orthorhombic crystal system with acentric P212121 space group and (II) packed in monoclinic system with centric P21/c space group. Intra-/intermolecular hydrogen bonds and weak van der Waals forces construct the supramolecular network in the crystal packing. The bandgap energy was estimated using diffuse reflectance spectral data by the application of the Kubelka–Munk algorithm. The non-linear optical response is examined by the Kurtz–Perry technique gave the result that the efficacy of crystal (I) is ~ 4 times greater than that of reference KDP. TG/DTA analysis reveals the thermal pattern of the compounds. Fingerprint plot used to locate and analyse the percentage contribution of hydrogen bonding interactions. First-order molecular hyperpolarizability calculated using theoretical calculations shows a significant microlevel nonlinearity in both cases. [ABSTRACT FROM AUTHOR]

Homogeneous thin films of Molybdenum oxide (MoO 3) were grown on quartz and glass substrates using the thermal evaporation method. XRD results showed that the MoO 3 powder has a polycrystalline structure with an orthorhombic crystal system whereas the MoO 3 thin films have amorphous nature. SEM images showed that the MoO 3 thin films have a nearly uniform surfaces with worm-like shape grains. The film thickness influences on the linear and nonlinear optical characteristics of MoO 3 thin films that were examined using spectrophotometric measurements and from which, the linear optical constants of the MoO 3 thin films were estimated. The electronic transition type was determined as a direct allowed one. The values of the optical band gap were obtained to be in the range of 3.88–3.72 eV. The dispersion parameters, third-order nonlinear optical susceptibility, and the nonlinear refractive index of the MoO 3 thin films were determined and interpreted in the light of the single oscillator model. The temperature dependence of the DC electrical conductivity and the corresponding conduction mechanism for the MoO 3 films were investigated at temperatures ranging from 303 to 463 K. [ABSTRACT FROM AUTHOR]

Marijuana and hemp represent two broad classes of Cannabis sativa plants that are distinguished based on the concentration of the psychoactive cannabinoid delta‐9‐tetrahydrocannabinol (Δ9‐THC). In this work, solvent extracts derived from marijuana and hemp were characterized using optical and spectroscopic techniques. The crystalline components of the solvent extracts were first analyzed using polarized light microscopy to determine optical properties, namely, crystal system, optical sign, and principle refractive indices. Crystals from the marijuana‐derived extracts exhibited an orthorhombic crystal system and were optically negative, with nβ between 1.6320 and 1.6330 ± 0.0002. In contrast, crystals from hemp‐derived extracts exhibited a monoclinic crystal system and were optically positive, with nβ between 1.600 and 1.6040 ± 0.0002. Crystals were further distinguished through infrared spectroscopy, which highlighted structural differences between the two sample types, primarily based on differences in O‐H stretching. Finally, single‐crystal X‐ray diffraction was used to definitively identify the crystalline components, confirming the presence of tetrahydrocannabinolic acid in marijuana‐derived extracts and cannabidiol in hemp‐derived extracts. Given the differences in crystal structure identified between marijuana‐derived and hemp‐derived solvent extracts, optical characterization provides a screening method to differentiate visually similar samples prior to confirmatory analysis. [ABSTRACT FROM AUTHOR]

Chromium doped Pr0.5Sr0.5Mn1-xCrxO3 (x= 0.0, 0.1, 0.2, 0.3, 0.4) system were synthesized by sol-gel method. The Xray diffraction patterns revealed the formation of single-phase orthorhombic structure (Pnma space group). The crystallite size was observed to vary from 26.12169 nm to 33.19551 nm with Cr doping concentration. The dislocation density was also observed to varied from 0.9074 x 10-3 to 1.4655 x 10-3nm-2 with change in Cr doping concentration. The micro strain was observed to increase from 36.8395 x 10-4 to 46.8197 x 10-4 with change in Cr doping concentration. There was no evidence of characteristic absorbance peaks for all the synthesized samples. The optical energy band gap was calculated using Kubelka-Munk equation based on Tauc's plot and observed in the range 0.52 to 1.12 eV. [ABSTRACT FROM AUTHOR]

The high-temperature superconductor like YBa2Cu3O6.5+δ was prepared by solid-state reaction method at calcination temperatures (900 °C). The crystal structure was confirmed using X-ray diffraction, and it was found that YBa2Cu3O6.5+δ showed orthorhombic phase with lattice parameters (a = 3.82030, b = 3.88548, and c = 11.6835 Å) with space group (Pmmm). The sample was sintered at sintering temperatures (900 °C) for (24 hr). The oxygen excess (δ) was nearly (0.36), which was effective in the appearing superconducting properties. The sample YBa2Cu3O6.86 had a critical temperature of about (92 K). The simulation on the XRD-pattern was necessary to predicate the shape of the unit cell and the position of atoms in the unit cell. The last is very important to find some theoretical date, which are benefit in the predication the conductivity parameters through the sequence's unit cells, which are useful in the conductivity mechanism. This mechanism is depending on the concept of interlayer coupling, so the number of the layers including the unit cell is effective parameter in the conductivity mechanism through the normal resistivity created. [ABSTRACT FROM AUTHOR]

By using the iridium(IV) complex (NBu4)2[IrBr6] (1) as a metalloligand towards a Cu(II) metal ion, three novel Ir(IV) one-dimensional (1D) compounds of formula {IrBr5(μ-Br)Cu(Meim)4}n (2), {IrBr5(μ-Br)Cu(Viim)4}n (3) and {IrBr5(μ-Br)Cu(Buim)4}n (4), [Meim = 1-methylimidazole; Viim = 1-vinylimidazole; Buim = 1-butylimidazole] have been prepared and structurally and magnetically characterised. Compounds 2, 3 and 4 crystallise in the triclinic, monoclinic and orthorhombic crystal systems with space groups P1¯, C2/c and Pccn, respectively. Each Ir(IV) ion in 1–4 is six-coordinate and bonded to six bromide ions in a quasi regular octahedral geometry. In compounds 2–4, the CuII ion shows an axially elongated octahedron with four N atoms, from four monodentate imidazole derivative ligands, that form the equatorial plane and two bromide ions that occupy the axial positions. Cu(II) and Ir(IV) ions are linked through bridging bromide anions generating Ir(IV)–Cu(II) chains [with intrachain Cu(II)⋯Ir(IV) distances covering the range of ca. 5.10–5.42 Å]. In the crystal lattice of 2 and 3 are observed significant intermolecular Ir–Br⋯Br–Ir contacts and π⋯Br interactions, which organize arrangements that contribute to stabilizing the crystal structure of these Ir(IV)-based compounds. DC magnetic susceptibility measurements reveal that 1 displays magnetic behaviour typical of noninteracting mononuclear centres with S = 1/2. Besides, antiferromagnetic behaviour (2 and 3) and ferromagnetic (4) exchange coupling occur between the Cu(II) and Ir(IV) metal ions in the one-dimensional bromo-bridged compounds 2–4. Moreover, the study of the AC magnetic susceptibility shows a field-induced slow relaxation of the magnetisation for 1, indicating the presence of the single-ion magnet (SIM) phenomenon for the magnetically isolated hexabromoiridate(IV) complex. [ABSTRACT FROM AUTHOR]

Novel three dimensional (3D) isostructural lead(II) halide coordination polymers [Pb(INO)X]n (X = Cl (1), Br (2), I (3); INO = isonicotinic acid N-oxide) have been synthesized via a branched-tube method. The compounds have been characterized by IR spectroscopy and powder X-ray diffraction (PXRD) analysis and their crystalline structures have been determined by single-crystal X-ray diffraction. Isostructural compounds 1–3 crystallize in the orthorhombic crystal system with the Pbcn space group. Two N-oxide groups of INO anions connect to a pair of adjacent Pb(II) ions to create a one-dimensional (1D) infinite zigzag chain and carboxylate groups connect the lead(II) ions resulting in [Pb2O2] units. Nanoplates of compounds 1–3 have also been synthesized under ultrasonic irradiation and characterized by IR spectroscopy, SEM and PXRD. Moreover, compounds 1–3 exhibited reversible solid-state crystal-to-crystal transformation under mechanochemical reactions. The thermal stability of these crystalline materials has been presented. The fluorescence features of these compounds have also been studied in solution for bulk and nanostructures at ambient temperature. [ABSTRACT FROM AUTHOR]

Based on the first-principles method, we predict two new stable BN allotropes: C12-BN and O16-BN, which belong to cubic and orthorhombic crystal systems, respectively. It is confirmed that both the phases are thermally and dynamically stable. The results of molecular dynamics simulations suggest that both the BN phases are highly stable even at high temperatures of 1000 K. In the case of mechanical properties, C12-BN has a bulk modulus of 359 GPa and a hardness of 43.4 GPa, making it a novel superhard material with potential technological and industrial applications. Electronic band calculations reveal that both C12-BN and O16-BN are insulators with direct band gaps of 3.02 eV and 3.54 eV, respectively. The XRD spectra of C12-BN and O16-BN are also simulated to provide more information for possible experimental observation. Our findings enrich the BN allotrope family and are expected to stimulate further experimental interest. [ABSTRACT FROM AUTHOR]

By the interaction of [Rh2(COE)4(μ-Cl)2] (COE = cyclooctene) with 1,2-bis[(2,6-diisopropyl phenyl)imino]acenaphthene (dpp-bian) new binuclear complex [Rh2(dpp-bian)2(μ-Cl)2]·2.72CH2Cl2 is obtained. The crystal structure is determined by the single crystal X-ray diffraction analysis. Compound 1·2.72CH2Cl2 crystallizes in the orthorhombic crystal system (space group Pnma) with unit cell parameters a = 51.200(3) Å, b = 22.3795(13) Å, c = 12.8631(8) Å, V = 14739.0(16) Å3, R = 0.0536. Each rhodium atom has a distorted square-planar environment formed by two dpp-bian N atoms and two bridging Cl atoms. Density functional theory calculations predict the existence of two isomers of the [Rh2(dpp-bian)2(μ-Cl)2] complex with similar formation energies. [ABSTRACT FROM AUTHOR]

The results of variable-temperature magnetic studies show that the magnetic interaction between the Ln(III) ions in B 3 b , B 5 b and B 6 b is mainly due to antiferromagnetic coupling as well as the depopulation of the Stark levels. The larger I i value of B 5 b compared with that of B 6 b also indicates that the magnetic interactions between the Ln(III) ions in B 5 b are stronger than that in B 6 b . Keywords: crystal structure; ionic liquid; lanthanide-organic frameworks; magnetism EN crystal structure ionic liquid lanthanide-organic frameworks magnetism 149 155 7 03/11/22 20220201 NES 220201 1 Introduction The exploratory preparation and investigation of lanthanide-organic frameworks (LOFs) have captured increasing attention in the last decades, driven largely by their various coordination geometries, peculiar luminescent and magnetic properties, as well as potential applications in gas adsorption, catalysis and additives in metallurgy [[1]], [[2]], [[3]], [[4]], [[5]], [[6]]. Each Gd(III) ion is coordinated to eight oxygen atoms from six carboxylate groups of the BTB ligands and one terminal water molecule, resulting in a distorted bicapped trigonal prismatic coordination geometry (Figure 1). [Extracted from the article]

Adjacent silicon atoms are located in the centre of a 12-verticles polyhedron (Figure 2), but it consists of both europium and silicon, unlike a polyhedron around the Si-Si pairs in Eu SB 5 sb Si SB 3 sb . From the COHP data, it can be concluded that the strongest interactions occur between Si-Si atoms -iCOHP = 1.904 eV (for EuSi) and -iCOHP = 1.927 eV (for Eu SB 5 sb Si SB 3 sb ). 3 Results and discussion 3.1 Crystal structure of Eu 5 Si 3 and EuSi The crystallographic data and details of the data collection from the single crystal of Eu SB 5 sb Si SB 3 sb silicide are listed in Table 1. Keywords: crystal structure; electrochemistry; intermetallics; rare earth silicide; X-ray diffraction EN crystal structure electrochemistry intermetallics rare earth silicide X-ray diffraction 99 109 11 03/11/22 20220201 NES 220201 1 Introduction Generally, the construction of an isothermal section of a multicomponent system gives us knowledge about the possible formation of complex compounds. [Extracted from the article]

Two-dimensional (2D) materials may have potential applications in thermoelectric devices. In this work, the thermoelectric properties of orthorhombic group IV-VI monolayers AB (A=Ge and Sn; B=S and Se) are systematically investigated by the first-principles calculations and semiclassical Boltzmann transport theory. The spin-orbit coupling (SOC) is considered for their electron part, which produces observable effects on the power factor, especially for n-type doping. According to the calculated ZT, the four monolayers exhibit diverse anisotropic thermoelectric properties although they have a similar hinge-like crystal structure. The GeS along zigzag and armchair directions shows the strongest anisotropy, while SnS and SnSe show mostly isotropic efficiency of thermoelectric conversion. This can be explained by the strength of anisotropy of their respective power factor and electronic and lattice thermal conductivities. The calculated results show that the ZT between n- and p-type doping has little difference for GeS, SnS, and SnSe. It is found that GeSe, SnS, and SnSe show better thermoelectric performance compared to GeS in n-type doping and that SnS and SnSe exhibit higher efficiency of thermoelectric conversion in p-type doping. Compared to other many 2D materials, orthorhombic group IV-VI monolayers AB (A=Ge and Sn; B=S and Se) may possess better thermoelectric performance due to lower lattice thermal conductivities. Our work would be beneficial to stimulate further theoretical and experimental works. [ABSTRACT FROM AUTHOR]

The magnetocaloric effect is observed in the 1:1:1 compound ErRhSi, which is a metamagnet is reported in this paper. ErRhSi crystallizes in the orthorhombic space group Pnma, adopting the TiNiSi structure type, with lattice parameters a(Å)=6.7903(5), b(Å)=4.1881(3), and c(Å)=7.3847(4). Our magnetic measurements confirm an antiferromagnetic phase transition at TN≈8.5K, also supported by the specific heat measurement. Crystal field effects of Er3+ are suggested by the inverse magnetic susceptibility data which do not conform to an ideal Curie-Weiss behaviour and also by the total entropy that attains Rln (2) at TN. Although the magnetic hysteresis indicates ErRhSi to be a soft magnet, several clear metamagnetic features are observed at 2K. Magnetic entropy change ΔSM=- 8.7J/kg-K is observed at about 9K with the application of 5T magnetic field. The corresponding adiabatic temperature change ΔTad is about 4K. Large magnetocaloric effects suggest that this material is suitable for the low temperature magnetic refrigeration. [ABSTRACT FROM AUTHOR]

A novel material, ZrScW2PO12, with negative thermal expansion (NTE) behavior, at least from 138 to 1300 K, and intense photoluminescence (PL) property is first reported in this paper. Temperature dependent Raman and PL spectral studies indicate that the material holds an orthorhombic structure down to about 74K and exhibits NTE property in the temperature range. The intense PL covering nearly the whole visible region was observed and can be deconvoluted into four bands, which present different shifts with elevation of temperature. The abundant optical property may be attributed to n- and p-type like co-doping effect and the specific structure with the abnormal thermal expansion property of the material. The integrated properties might suggest potential applications of this material in light emitting diodes and other light emitting devices. [ABSTRACT FROM AUTHOR]

A novel material, ZrScW2PO12, with negative thermal expansion (NTE) behavior, at least from 138 to 1300 K, and intense photoluminescence (PL) property is first reported in this paper. Temperature dependent Raman and PL spectral studies indicate that the material holds an orthorhombic structure down to about 74K and exhibits NTE property in the temperature range. The intense PL covering nearly the whole visible region was observed and can be deconvoluted into four bands, which present different shifts with elevation of temperature. The abundant optical property may be attributed to n- and p-type like co-doping effect and the specific structure with the abnormal thermal expansion property of the material. The integrated properties might suggest potential applications of this material in light emitting diodes and other light emitting devices. [ABSTRACT FROM AUTHOR]

High-pressure phase of boron oxide, orthorhombic β-B2O3, has been studied in situ by synchrotron X-ray diffraction to 22 GPa and Raman scattering to 46 GPa at room temperature. The bulk modulus of β-B2O3 has been found to be 169(3) GPa that is in good agreement with our ab initio calculations. Raman and IR spectra of β-B2O3 have been measured at ambient pressure; all experimentally observed bands have been attributed to the theoretically calculated ones, and the mode assignment has been performed. Based on the data on Raman shift as a function of pressure, combined with equation-of-state data, the Gr€uneisen parameters of all experimentally observed Raman bands have been calculated. β-B2O3 enriched by 10B isotope has been synthesized, and the effect of boron isotopic substitution on Raman spectra has been studied. [ABSTRACT FROM AUTHOR]

A methodology is worked out to retrieve the numerical values of all the main parameters of the six-dimensional adiabatic potential energy surface (APES) of a polyatomic system with a quadratic T-term Jahn-Teller effect (JTE) from the ultrasound experiments. The method is based on a verified assumption that ultrasound attenuation and speed encounter anomalies when the direction of propagation and polarization of its wave of strain coincides with the characteristic directions of symmetry breaking in the JTE. For the SrF2:Cr crystal, employed as a basic example, we observed anomaly peaks in the temperature dependence of attenuation of ultrasound at frequencies of 50-160 MHz in the temperature interval of 40-60K for the wave propagating along the [110] direction, for both the longitudinal and the shear modes, the latter with two polarizations along the [001] and [1̄10] axes, respectively. We show that these anomalies are due to the ultrasound relaxation by the system of non-interacting Cr2+ JT centers with orthorhombic local distortions. The interpretation of the experimental findings is based on the T2g ⊗ (eg + t2g) JTE problem including the linear and the quadratic terms of vibronic interactions in the Hamiltonian and the same-symmetry modes reduced to one interaction mode. Combining the experimental results with a theoretical analysis, we show that on the complicated six-dimensional APES of this system with three tetragonal, four trigonal, and six orthorhombic extrema points, the latter are global minima, while the former are saddle points, and we estimate numerically all the main parameters of this surface, including the linear and quadratic vibronic coupling constants, the primary force constants, the coordinates of all the extrema points and their energies, the energy barrier between the orthorhombic minima, and the tunneling splitting of the ground vibrational states. To our knowledge, such a based-on-experimental-data numerical reconstruction of the APES of a JTE problem in the five-dimensional space of all active tetragonal and trigonal displacements has not been reported before. [ABSTRACT FROM AUTHOR]

In this paper we provide an accurate high-pressure structural and optical study of the MAPbI3 hybrid perovskite. Structural data show the presence of a phase transition toward an orthorhombic structure around 0.3 GPa followed by full amorphization of the system above 3 GPa. After releasing the pressure, the system keeps the high-pressure orthorhombic phase. The occurrence of these structural transitions is further confirmed by pressure induced variations of the photoluminescence signal at high pressure. These variations clearly indicate that the bandgap value and the electronic structure of MAPI change across the phase transition. [ABSTRACT FROM AUTHOR]

Polycrystalline β-PbO films were grown by pulsed laser deposition in atmospheres ranging from oxygen-poor (the oxygen pressure of 0.01 Pa) to oxygen-rich (13 Pa) conditions, and the oxygen chemical potential was further enhanced by ozone annealing to examine hole doping. It was found that each of the as-grown β-PbO films showed poor electrical conductivity, σ?7.1?×?10² S cm-1) but it is the result of the formation of an n-type PbO2 phase because oxygen chemical potential exceeded the phase boundary limit. The striking difference in carrier generation between PbO and SnO is discussed based on the electronic structures calculated by density functional theory. [ABSTRACT FROM AUTHOR]

X-ray powder diffraction and Raman scattering of LiTaO3 (LT) and (Li,Mg)TaO3 (LMT) have been measured under pressure up to 46 GPa. Above 30 GPa, the ferroelectric rhombohedral phase (R3c, Z = 6) of LiTaO3 transforms to a paraelectric orthorhombic phase (Pnma with Z = 4) with a large hysteresis. Rietveld profile fitting analysis shows that the Li-O bond is compressed and approaches that of Ta-O with pressure. The cation distribution analysis of the orthorhombic perovskite structure shows that Li and Ta are located in the octahedral 8-fold coordination sites. Difference Fourier ∣Fobs(hkl)∣ - ∣Fcal(hkl)∣ maps of LiTaO3 and (Li,Mg)TaO3 indicate polarization in the c axis direction and a more distinct electron density distribution around the Ta position for (Li,Mg)TaO3 compared to LiTaO3. The observed effective charges indicate that for (Li,Mg)TaO3 without vacancies Ta5+ becomes less ionized as a function of Mg substitution. Considering both site occupancy and effective charge analysis, Ta5+ is reduced to Ta4.13+. Mg2+ and O2- change to Mg1.643+ and O1.732 -, respectively. The space- and time-averaged structures of the dynamical vibration of atoms can be elucidated from the electron density analysis by difference Fourier and temperature factors T(hkl) in the structure refinement. The refinement of the temperature factor is consistent with the cation distribution assuming full stoichiometry. The residual electron density induced from the excess electron in (Li,Mg)TaO3 indicates more electrons around the Ta site, as confirmed by the effective charge analysis. Raman spectra of LiTaO3 and (Li,Mg)TaO3 show notable changes over the measured pressure range. Raman peaks centered at 250 cm-1 and 350 cm-1 at ambient pressure merge above 8 GPa, which we associate with the diminishing of difference in distances between Li-O and Ta-O bonds with pressure in both materials. Raman spectra show significant changes at 28 GPa and 33 GPa for LT and LMT, respectively, due to the structural transition from R3c to Pnma consistent with the x-ray diffraction results. [ABSTRACT FROM AUTHOR]