Pyrochlore-like Local Structure in Globally Disordered YZrO: Evidence and Reasoning by Combined Theoretical and Experimental Study.

Even though technological relevance for nuclear and oxide fuel cell application has persuaded a large number of investigations on the YZrO system, its local structure still remains ambiguous and debatable. While diffraction-based investigations claim a lack of local ordering, the MAS NMR and Raman spectroscopic investigations speculate the presence of local ordering. Besides, a correlation between the local and global structures of YZrO is also missing to date.

An Iron-Based Fluorophosphate Cathode Material for K-Ion Batteries.

The development of a tavorite structured K- transition metal (T)- fluorophosphate, having earth-abundant Fe as the only T, crystallizing in the orthorhombic crystal system and facilitating stable-cum-reversible electrochemical K-extraction/insertion, has been reported here. Synthesized using low-cost precursors, KFePOF has also been found to be air-stable. Detailed information pertaining to the bonding/structure, including lattice site occupancy, have been obtained via diffraction, Raman spectroscopy and FTIR, with XPS, Mössbauer and ESR revealing the oxidation states and nature of Fe in the as-synthesized condition and upon being subjected to electrochemical potassiation/depotassiation.

Large Local Internal Stress in an Elastically Bent Molecular Crystal Revealed by Raman Shifts.

The structural dynamics involved in the mechanical flexibility of molecular crystals and the internal stress in such flexible materials remain obscure. Here, the study reports an elastically bending lipidated molecular crystal that shows systematic shifts in characteristic vibrational frequencies across the bent crystal region - revealing the nature of structural changes during bending and the local internal stress distribution. The blueshifts in the bond stretching modes (such as C═O and C-H modes) in the inner arc region and redshifts in the outer arc region of the bent crystals observed via micro-Raman mapping are counterintuitive to the bending models based on intermolecular hydrogen bonds.

Pressure driven polymorphic transitions in nanocrystalline LuO, TmO and EuO.

The crystallite size of the materials considerably influences the material properties, including their compressibility and resistance to external forces and the stability of the crystalline structure; a corresponding study for which, so far, has been limited for the important class of nanocrystalline Rare Earth Sesquioxides (REOs). In the present study, we report the crystallographic structural transitions in nanocrystalline Rare Earth Oxides (REOs) under the influence of pressure, investigated via high-energy X-Ray Diffraction (XRD) measurements. The study has been carried out on three of the REOs, namely Lutetium oxide (LuO), Thulium oxide (TmO) and Europium oxide (EuO) up to the pressures of 33, 22 and 11 GPa, respectively.

Facile and Scalable Development of High-Performance Carbon-Free Tin-Based Anodes for Sodium-Ion Batteries.

Tin (Sn)-based anodes for sodium (Na)-ion batteries possess higher Na-storage capacity and better safety aspects compared to hard carbon -based anodes but suffer from poor cyclic stability due to volume expansion/contraction and concomitant loss in mechanical integrity during sodiation/desodiation. To address this, the usage of nanoscaled electrode-active particles and nanoscaled-carbon-based buffers has been explored, but with compromises with the tap density, accrued irreversible surface reactions, overall capacity (for "inactive" carbon), and adoption of non-scalable/complex preparation routes. Against this backdrop, anode-active "layered" bismuth (Bi) has been incorporated with Sn via a facile-cum-scalable mechanical-milling approach, leading to individual electrode-active particles being composed of well-dispersed Sn and Bi phases.

Development of a high-rate-capable O3-structured 'layered' Na transition metal oxide by tuning the cation-oxygen bond covalency.

By developing a high-rate-capable O3-structured Na(LiNiSiTiCuMg)O-based cathode material for Na-ion batteries, wherein partial substitution of more electronegative Si for Ti in the transition metal layer has weakened-cum-lengthened the Na-O bond, enlarged the 'inter-slab' spacing and, thus, enhanced the Na-transport kinetics, a design criterion has been laid-out in the above context.

Understanding the Effects of Tetrahedral Site Occupancy by the Zn Dopant in Li-NMCs toward High-Voltage Compositional-Structural-Mechanical Stability via Operando and 3D Atom Probe Tomography Studies.

Ni-containing "layered"/cation-ordered LiTOs (T = transition metal) suffer from Ni-migration to the Li-layer at the unit cell level, concomitant transformation to a spinel/rock salt structure, hindrance toward Li-transport, and, thus, fading in Li-storage capacity during electrochemical cycling (i.e., repeated delithiation/lithiation), especially upon deep delithiation (i.

Pressure driven structural phase transition in EuTaO: experimental and first principles investigations.

In this article we report the synthesis, characterization and high pressure (HP) investigation on technologically important, rare earth orthotantalate, EuTaO. Single phase polycrystalline sample of EuTaOhas been synthesized by solid state reaction method adopting monoclinic M'-type fergusonite phase with space group2/. Structural and vibrational properties of as synthesized compound are investigated using synchrotron based x-ray powder diffraction, and Raman spectroscopic techniques respectively.

Growth of sillenite BiFeO single crystals: structural, thermal, optical, photocatalytic features and first principle calculations.

Ideal sillenite type BiFeO (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic BiFeO structure with single crystal parameters. Occurrence of rare Fe state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS).

Influence of pressure on the transport, magnetic, and structural properties of superconducting CrNbSe single crystal.

We investigate the superconducting critical current density ( ), transition temperature ( ), and flux pinning properties under hydrostatic pressure () for CrNbSe single crystal. The application of enhances in both electrical resistivity (∼0.38 K GPa: 0 ≤ ≤ 2.

Augmentation of the step-by-step Energy-Scanning EXAFS beamline BL-09 to continuous-scan EXAFS mode at INDUS-2 SRS.

An innovative scheme to carry out continuous-scan X-ray absorption spectroscopy (XAS) measurements similar to quick-EXAFS mode at the Energy-Scanning EXAFS beamline BL-09 at INDUS-2 synchrotron source (Indore, India), which is generally operated in step-by-step scanning mode, is presented. The continuous XAS mode has been implemented by adopting a continuous-scan scheme of the double-crystal monochromator and on-the-fly measurement of incident and transmitted intensities. This enabled a high signal-to-noise ratio to be maintained and the acquisition time was reduced to a few seconds from tens of minutes or hours.

Anomalous high pressure behaviour in nanosized rare earth sesquioxides.

We report Raman spectroscopic studies of the nanosized rare earth sesquioxides, namely yttrium sesquioxide (Y(2)O(3)), gadolinium sesquioxide (Gd(2)O(3)) and samarium sesquioxide (Sm(2)O(3)), under high pressure. The samples were characterized using x-ray diffraction, Raman spectroscopy and atomic force microscopy at atmospheric pressures. Y(2)O(3) and Gd(2)O(3) were found to be cubic at ambient, while Sm(2)O(3) was found to be predominantly cubic with a small fraction of monoclinic phase.