Author: S. Nagabhusan Achary

ChemInform Abstract: New Polymorph of InVO4: A High-Pressure Structure with Six-Coordinated Vanadium.

2014

High-pressure XRD and Raman spectroscopy on orthorhombic InVO4 (space group Cmcm, Z = 4) reveal the existence of a new wolframite-type polymorph of InVO4 near 7 GPa.

Crystallographysymbols.namesakechemistryGroup (periodic table)symbolsStructure (category theory)Vanadiumchemistry.chemical_elementOrthorhombic crystal systemGeneral MedicineSpace (mathematics)Raman spectroscopyChemInform

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Phase Transitions of BiVO4 under High Pressure and High Temperature

2022

We have studied the occurrence of phase transitions in two polymorphs of BiVO4 under high-pressure and high-temperature conditions by means of X-ray diffraction measurements. The fergusonite polymorph undergoes a phase transition at 1.5(1) GPa and room temperature into a tetragonal scheelite-type structure. The same transition takes place at 523(1) K and ambient pressure. A second phase transition takes place at room temperature under compression at 16(1) GPa. The transition is from the tetragonal scheelite structure to a monoclinic structure (space group P21/c). All observed phase transitions are reversible. The zircon polymorph counterpart also transforms under compression into the scheel…

General Energychemical structurecompressibilitydiffractionPhysical and Theoretical ChemistryUNESCO::CIENCIAS TECNOLÓGICASSurfaces Coatings and FilmsElectronic Optical and Magnetic Materialsphase transitionsthermal expansion

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ChemInform Abstract: Pressure-Induced Transformations in PrVO4and SmVO4and Isolation of High-Pressure Metastable Phases.

2013

High-pressure phases of PrVO4 and SmVO4 are synthesized from the zircon-structured compounds at 12 GPa and room temperature (24 h).

LanthanideChemistryMetastabilityHigh pressureInorganic chemistryAnalytical chemistryGeneral MedicineChemInform

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Pressure Impact on the Stability and Distortion of the Crystal Structure of CeScO3

2017

[EN] The effects of high pressure on the crystal structure of orthorhombic (Pnma) perovskite-type cerium scandate were studied in situ under high pressure by means of synchrotron X-ray powder diffraction, using a diamond-anvil cell. We found that the perovskite-type crystal structure remains stable up to 40 GPa, the highest pressure reached in the experiments. The evolution of unit-cell parameters with pressure indicated an anisotropic compression. The room-temperature pressure¿volume equation of state (EOS) obtained from the experiments indicated the EOS parameters V0 = 262.5(3) Å3 , B0 = 165(7) GPa, and B0¿ = 6.3(5). From the evolution of microscopic structural parameters like bond distan…

Equation of stateXRDFOS: Physical scienceschemistry.chemical_elementThermodynamics02 engineering and technologyCrystal structurePerovskite01 natural sciencesInorganic ChemistryPhysics - Chemical Physics0103 physical sciencesScandiumPhysical and Theoretical Chemistry010306 general physicsAnisotropyPerovskite (structure)Chemical Physics (physics.chem-ph)Condensed Matter - Materials ScienceCrystal structureMaterials Science (cond-mat.mtrl-sci)021001 nanoscience & nanotechnologyCerium scandateCondensed Matter - Other Condensed MatterHigh pressureCeriumchemistryFISICA APLICADAOrthorhombic crystal system0210 nano-technologyPowder diffractionOther Condensed Matter (cond-mat.other)Inorganic Chemistry

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New polymorph of InVO4: A high-pressure structure with six-coordinated vanadium

2013

A new wolframite-type polymorph of InVO4 is identified under compression near 7 GPa by in situ high-pressure (HP) X-ray diffraction (XRD) and Raman spectroscopic investigations on the stable orthorhombic InVO4. The structural transition is accompanied by a large volume collapse (Delta V/V = -14%) and a drastic increase in bulk modulus (from 69 to 168 GPa). Both techniques also show the existence of a third phase coexisting with the low- and high-pressure phases in a limited pressure range close to the transition pressure. XRD studies revealed a highly anisotropic compression in orthorhombic InVO4. In addition, the compressibility becomes nonlinear in the HP polymorph. The volume collapse in…

DiffractionVanadiumchemistry.chemical_elementOrtho-vanadatesInorganic Chemistrysymbols.namesakeThird phaseVisible-light irradiationFormsPhysical and Theoretical ChemistrySpectroscopySpectroscopyBulk modulusCRYSTALChemistryCRVO4TIVO4CrystallographyPhaseFISICA APLICADATransitionCompressibilitysymbolsOrthorhombic crystal systemRaman spectroscopyDiffraction

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High-Pressure High-Temperature Stability and Thermal Equation of State of Zircon-Type Erbium Vanadate.

2018

Inorganic chemistry 57(21), 14005 - 14012 (2018). doi:10.1021/acs.inorgchem.8b01808

DiffractionDYNAMICSEquation of statePhase boundaryThermodynamics02 engineering and technologyzircon010402 general chemistry01 natural sciencesThermal expansionInorganic Chemistrychemistry.chemical_compoundX-RAY-DIFFRACTIONPhase (matter)Physical and Theoretical ChemistryChemistryX-RAY-DIFFRACTION; DYNAMICS021001 nanoscience & nanotechnology5400104 chemical scienceshigh pressureScheeliteX-ray crystallographyddc:5400210 nano-technologyZirconInorganic chemistry

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Experimental and Theoretical Investigations on Structural and Vibrational Properties of Melilite-Type Sr2ZnGe2O7 at High Pressure and Delineation of …

2015

We report a combined experimental and theoretical study of melilite-type germanate, Sr2ZnGe2O7, under compression. In situ high-pressure X-ray diffraction and Raman scattering measurements up to 22 GPa were complemented with first-principles theoretical calculations of structural and lattice dynamics properties. Our experiments show that the tetragonal structure of Sr2ZnGe2O7 at ambient conditions transforms reversibly to a monoclinic phase above 12.2 Gpa with similar to 1% volume drop at the phase transition pressure. Density functional calculations indicate the transition pressure at, similar to 13 GPa, which agrees well with the experimental value. The structure of the high-pressure mono…

Phase transitionThermodynamicsengineering.materialMagnetic-PropertiesInorganic ChemistryCondensed Matter::Materials ScienceTetragonal crystal systemX-Ray DiffractionNatural meliliteGermanatePhysical and Theoretical ChemistryCrystal-StructureThermal-ExpansionAkermaniteLow-TemperatureChemistryRaman-SpectraMeliliteSolid-SolutionFISICA APLICADACompressibilityengineeringCondensed Matter::Strongly Correlated ElectronsCascaded CHI((3))Ambient pressureSolid solutionMonoclinic crystal systemInorganic chemistry

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ChemInform Abstract: Experimental and Theoretical Investigations on Structural and Vibrational Properties of Melilite-Type Sr2ZnGe2O7at High Pressure…

2015

The title compound is characterized by high-pressure powder XRD and Raman scattering measurements up to 22 GPa, and by DFT calculations.

symbols.namesakeCrystallographyChemistryHigh pressurePhase (matter)symbolsengineeringMeliliteGeneral MedicinePowder xrdengineering.materialRaman scatteringMonoclinic crystal systemChemInform

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Pressure-Induced Transformations in PrVO4 and SmVO4 and Isolation of High-Pressure Metastable Phases

2013

Zircon-type PrVO4 and SmVO4 have been studied by high-pressure Raman spectroscopy up to 17 GPa. The occurrence of phase transitions has been detected when compression exceeds 6 GPa. The transformations are not reversible. Raman spectra of the high-pressure phases show similarities with those expected for a monazite-type phase in PrVO4 and a scheelite-type phase in SmVO4.The high-pressure phases have been also synthesized using a large-volume press and recovered at ambient conditions. X-ray diffraction measurements of the metastable products recovered after decompression confirms the monazite (PrVO4) and scheelite (SmVO4) structures of the high-pressure phases. Based upon optical properties …

DiffractionPhase transitionChemistryAnalytical chemistryInorganic Chemistrysymbols.namesakechemistry.chemical_compoundPhase (matter)ScheeliteMonaziteMetastabilitysymbolsPhysical and Theoretical ChemistryRaman spectroscopyHydrogen productionInorganic Chemistry

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Pressure-Induced Hexagonal to Monoclinic Phase Transition of Partially Hydrated CePO4

2019

We present a study of the pressure dependence of the structure of partially hydrated hexagonal CePO 4 up to 21 GPa using synchrotron powder X-ray diffraction. At a pressure of 10 GPa, a second-order structural phase transition is observed, associated with a novel polymorph. The previously unknown high-pressure phase has a monoclinic structure with a similar atomic arrangement as the low-pressure phase, but with reduced symmetry, belonging to space group C2. Group-subgroup relations hold for the space symmetry groups of both structures. There is no detectable volume discontinuity at the phase transition. Here we provide structural information on the new phase and determine the axial compress…

DiffractionPhase transitionHigh-pressure010405 organic chemistryHexagonal crystal systemChemistryCiencias FísicasPressure dependence010402 general chemistry01 natural sciencesSynchrotronPhosphates0104 chemical scienceslaw.inventionInorganic ChemistryCrystallographylawPhysical and Theoretical ChemistryCIENCIAS NATURALES Y EXACTASFísica de los Materiales CondensadosMonoclinic crystal systemInorganic Chemistry

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Stability of FeVO4 under Pressure: An X-ray Diffraction and First-Principles Study

2018

The high-pressure behavior of the crystalline structure FeVO4 has been studied by means of X-ray diffraction using a diamond-anvil cell and first-principles calculations. The experiments were carried out up to a pressure of 12.3 GPa, until now the highest pressure reached to study an FeVO4 compound. High-pressure X-ray diffraction measurements show that the triclinic P1 (FeVO4-I) phase remains stable up to ≈3 GPa; then a first-order phase transition to a new monoclinic polymorph of FeVO4 (FeVO4-II′) with space group C2/m is observed, having an α-MnMoO4-type structure. A second first-order phase transition is observed around 5 GPa toward the monoclinic (P2/c) wolframite-type FeVO4-IV structu…

DiffractionPhase transitionChemistry02 engineering and technologyCrystal structureTriclinic crystal system010402 general chemistry021001 nanoscience & nanotechnology01 natural sciencesStability (probability)0104 chemical sciencesInorganic ChemistryCrystallographyPhase (matter)X-ray crystallographyPhysical and Theoretical Chemistry0210 nano-technologyMonoclinic crystal systemInorganic Chemistry

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High-pressure crystal structure, lattice vibrations, and band structure of BiSbO4

2016

The high-pressure crystal structure, lattice-vibrations HP crystal structure, lattice vibrations, and band , and electronic band structure of BiSbO4 were studied by ab initio simulations. We also performed Raman spectroscopy, infrared spectroscopy, and diffuse-reflectance measurements, as well as synchrotron powder X-ray diffraction. High-pressure X-ray diffraction measurements show that the crystal structure of BiSbO4 remains stable up to at least 70 GPa, unlike other known MTO4-type ternary oxides. These experiments also give information on the pressure dependence of the unit-cell parameters. Calculations properly describe the crystal structure of BiSbO4 and the changes induced by pressur…

DiffractionAb initioInfrared spectroscopy02 engineering and technologyCrystal structure010402 general chemistry01 natural sciencesMolecular physicsInorganic Chemistrysymbols.namesakeDegradationPhysical and Theoretical ChemistryElectronic band structureChemistryCompressionRefinement021001 nanoscience & nanotechnology0104 chemical sciencesCrystallographyPowder diffractionMolecular vibrationFISICA APLICADATransitionsymbols0210 nano-technologyRaman spectroscopyPowder diffraction

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CSD 1852498: Experimental Crystal Structure Determination

2018

Related Article: Javier Ruiz-Fuertes, Domingo Martínez-García, Tomás Marqueño, Daniel Errandonea, Simon G. MacLeod, Thomas Bernert, Eiken Haussühl, David Santamaría-Pérez, Jordi Ibáñez, Anitha Mallavarapu, S. Nagabhusan Achary, Catalin Popescu, and Marco Bettinelli|2018|Inorg.Chem.|57|14005|doi:10.1021/acs.inorgchem.8b01808