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.

A new compact symmetric shear diamond anvil cell for in situ high-pressure-torsion studies.

In situ studies under severe plastic deformation at high pressures, employing shear diamond anvil cells, have recently gained much interest in the high-pressure community owing to their potential applications in material processing methods, mechanochemistry, and geophysics. These studies, combined with multi-scale computational simulations, provide important insights into the transient hierarchical microstructural evolution, structural phase transitions, and orientation relationship between parent and daughter phases and help establish the kinetics of strain-induced phase transitions under severe plastic deformation. The existing SDACs are mostly used in axial x-ray diffraction geometry due to geometrical constraints providing less reliable information about stress states and texture.

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.

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.

High pressure Raman investigation on trans-urocanic acid.

Trans-urocanic acid (t-UCA) is an important epidermal UV protector predominantly found in human skin. Exposure of UV radiation triggers photoisomerization of t-UCA into its other conformer, cis-urocanic acid (cis-UCA), which has been shown to be a mediator of UV-induced immune-suppression leading to skin cancer. In this report, we present the investigation of molecular changes of t-UCA under high pressures by in-situ high pressure Raman spectroscopy.

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.

Spectroscopic studies of temperature induced phase transitions in metal-organic complex trans-PtCl(PEt).

Tuning of molecular and electronic properties of Pt(II)-organic complexes have a profound effect on their applications in the fields of technology, pharmaceuticals and crystal engineering. Here, we present combined infrared and Raman spectroscopic investigations on trans-PtCl(PEt) systematically carried out at various temperatures from 300 to 4.2 K in a wide spectral range.

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.

Protein crystallography beamline (PX-BL21) at Indus-2 synchrotron.

The protein crystallography beamline (PX-BL21), installed at the 1.5 T bending-magnet port at the Indian synchrotron (Indus-2), is now available to users. The beamline can be used for X-ray diffraction measurements on a single crystal of macromolecules such as proteins, nucleic acids and their complexes.

Structural phase transitions in trigonal Selenium induce the formation of a disordered phase.

Arguments based on the Mermin-Wagner theorem suggest that the quasi-1D trigonal phase of Se should be unstable against long wavelength perturbations. Consisting of parallel Se-Se chains, this essentially fragile solid undergoes a partial transition to a monoclinic structure (consisting of 8-membered rings) at low temperatures (≈50 K), and to a distorted trigonal phase at moderate pressures (≈3GPa). Experimental investigations on sub-millimeter-sized single crystals provide clear evidence that these transitions occur via a novel and counter-intuitive route.

High pressure iso-structural phase transition in BiMn2O5.

The high pressure behavior of multiferroic BiMn2O5 has been investigated using powder x-ray diffraction and Raman scattering techniques as well as density functional theory based first principles calculations. Our investigations show a reversible iso-structural phase transition in BiMn2O5 above 10 GPa. The compressibility along the c axis, i.

Pressure induced structural phase transition in triglycine sulfate and triglycine selenate.

To elucidate the cause of destruction of ferroelectricity with pressure in triglycine sulfate and triglycine selenate, we have investigated these compounds with the help of Raman measurements as well as first principles total energy and structural optimization calculations. Our results show that, beyond the critical pressures, the loss of ferroelectricity in these compounds is due to the conformational change in one of the three glycine ions of these crystals. Our studies suggest that pressure induced phase transition might be of displacive nature unlike the temperature induced ferroelectric phase transition in these crystals which is known to be of order-disorder type.

Pressure-induced structural phase transformations in silicon nanowires.

High-pressure structural behavior of silicon nanowires is investigated up to approximately 22 GPa using angle dispersive X-ray diffraction measurements. Silicon nanowires transform from the cubic to the beta-tin phase at 7.5-10.