A5009379833- Crystal Structures and Properties
- High-pressure geophysics and materials
- Chalcogenide Semiconductor Thin Films
- 2D Materials and Applications
- Topological Materials and Phenomena
- Astro and Planetary Science
- Solid-state spectroscopy and crystallography
- Astrophysics and Star Formation Studies
- Advanced Thermoelectric Materials and Devices
- Planetary Science and Exploration
- Atmospheric aerosols and clouds
- Boron and Carbon Nanomaterials Research
- Iron-based superconductors research
- Atmospheric chemistry and aerosols
- Inorganic Chemistry and Materials
- Atmospheric Ozone and Climate
- Gas Sensing Nanomaterials and Sensors
- Rare-earth and actinide compounds
- Phase-change materials and chalcogenides
- Quantum Dots Synthesis And Properties
- Stellar, planetary, and galactic studies
- Aeolian processes and effects
- Transition Metal Oxide Nanomaterials
- ZnO doping and properties
- Thermal properties of materials
Universitat Politècnica de València
2015-2024
Universidad de La Laguna
2014
University College London
2014
Academy of Sciences of Moldova
2014
Instituto Tecnológico del Calzado y Conexas
2008
Escola Politècnica Superior d'Alcoi
2008
Universitat de Miguel Hernández d'Elx
2002
The structural and vibrational properties of bismuth selenide (Bi${}_{2}$Se${}_{3}$) have been studied by means x-ray diffraction Raman scattering measurements up to 20 30 GPa, respectively. complemented with ab initio total-energy lattice dynamics calculations. Our experimental results evidence a phase transition from the low-pressure rhombohedral ($R$-3$m$) (\ensuremath{\alpha}-Bi${}_{2}$Se${}_{3}$) sixfold coordination for Bi monoclinic $C$2/$m$ structure...
We report an experimental and theoretical lattice dynamics study of antimony telluride (Sb${}_{2}$Te${}_{3}$) up to 26 GPa together with a its structural stability under pressure. Raman-active modes the low-pressure rhombohedral (R-3m) phase were observed 7.7 GPa. Changes frequencies linewidths around 3.5 where electronic topological transition was previously found. Raman-mode changes evidence transitions at 7.7, 14.5, 25 The pressure coefficients new phases above 14.5 agree those calculated...
We report an experimental and theoretical lattice dynamics study of bismuth telluride (Bi${}_{2}$Te${}_{3}$) up to 23 GPa together with the optical absorption reflection 10 GPa. The indirect bandgap low-pressure rhombohedral (R-3$m$) phase (\ensuremath{\alpha}-Bi${}_{2}$Te${}_{3}$) was observed decrease pressure at a rate \ensuremath{-}6 meV/GPa. In regard dynamics, Raman-active modes \ensuremath{\alpha}-Bi${}_{2}$Te${}_{3}$ were 7.4 dependence their frequency width provides evidence...
Raman scattering measurements and lattice-dynamics calculations were performed on magnesium tungstate (MgWO${}_{4}$) under high pressure up to 41 GPa. Experiments carried out a selection of media. The influence nonhydrostaticity the structural properties MgWO${}_{4}$ isomorphic compounds is examined. Under quasihydrostatic conditions, phase transition was found at 26 GPa in MgWO${}_{4}$. high-pressure tentatively assigned triclinic structure similar that CuWO${}_{4}$. We also report discuss...
Abstract Bi 2 Se 3 , Te and Sb are narrow bandgap semiconductors with tetradymite crystal structure (R‐3m) which have been extensively studied along their alloys due to promising operation as thermoelectric materials in the temperature range between 300 500 K. Studies on these layered increased tremendously last years since they recently predicted demonstrated behave 3D topological insulators. In particular, a number of high‐pressure studies done recent materials. this work we summarize main...
We report an experimental and theoretical study of antimony oxide (Sb${}_{2}$O${}_{3}$) in its cubic phase (senarmontite) under high pressure. X-ray diffraction Raman scattering measurements up to 18 25 GPa, respectively, have been complemented with ab initio total-energy lattice-dynamics calculations. do not provide evidence a space-group symmetry change senarmontite GPa. However, changes the pressure coefficients mode frequencies at 3.5 10 respectively. The behavior modes increasing GPa is...
We report a joint experimental and theoretical study of the structural vibrational properties synthetic sphaerobismoite (β-Bi2O3) at high pressures in which room-temperature angle-dispersive X-ray diffraction (XRD) Raman scattering measurements have been complemented with ab initio total-energy lattice dynamics calculations. Striking changes spectra were observed around 2 GPa, whereas evidence no change tetragonal symmetry compound up to 20 GPa; however, significant exists compressibility...
α(R)-In2Se3 has been experimentally and theoretically studied under compression at room temperature by means of X-ray diffraction Raman scattering measurements as well ab initio total-energy lattice-dynamics calculations. Our study confirmed the α (R3m) → β′ (C2/m) β (R3̅m) sequence pressure-induced phase transitions allowed us to understand mechanism monoclinic C2/m rhombohedral R3̅m transition. The enhances its symmetry gradually until a complete transformation structure is attained above...
We report a joint experimental and theoretical study of the structural, vibrational, elastic, optical, electronic properties layered high-mobility semiconductor Bi2O2Se at high pressure. A good agreement between experiments ab initio calculations is observed for equation state, pressure coefficients Raman-active modes bandgap material. In particular, detailed description vibrational provided. Unlike other Sillén-type compounds which undergo tetragonal to collapsed pressure-induced phase...
High pressure X-ray diffraction, Raman scattering, and electrical measurements, together with theoretical calculations, which include the analysis of topological electron density electronic localization function, evidence presence an isostructural phase transition around 2 GPa, a Fermi resonance 3.5 pressure-induced decomposition SnSb2Te4 into high-pressure phases its parent binary compounds (α-Sb2Te3 SnTe) above 7 GPa. The internal polyhedral compressibility, behavior Raman-active modes,...
We report an extensive study of the optical and structural properties NiWO4 combining experiments density functional theory calculations. have obtained accurate information on pressure effect crystal structure determining equation state compressibility tensor. also determined dependence band gap finding that it decreases under compression because contribution Ni 3d states to top valence band. sub-band-gap spectrum showing five bands observed at 0.95, 1.48, 1.70, 2.40, 2.70 eV correspond...
High-pressure optical absorption and Raman scattering measurements have been performed in defect chalcopyrite (DC) CdGa2Se4 up to 22 GPa during two pressure cycles investigate the pressure-induced order-disorder phase transitions taking place this ordered-vacancy compound. Our reveal that on decreasing from GPa, sample does not revert initial but likely a disordered zinc blende (DZ) structure direct bandgap Raman-active modes of which measured second upstroke. complemented with electronic...
This work reports an experimental and theoretical lattice dynamics study of nanocrystalline Y3Ga5O12 (YGG) garnet at high pressures. Raman scattering measurements in Tm3+-doped YGG performed up to 29 GPa have been compared ab initio calculations for bulk carried out 89 GPa. Good agreement between the vibrational modes crystal measured nanocrystals is found. The contribution GaO4 tetrahedra GaO6 octahedra different phonon discussed on basis calculated total partial density states. Symmetries,...
We report a study of the structural, vibrational, and electronic properties layered monoclinic arsenic telluride (α-As2Te3) at high pressures. Powder X-ray diffraction Raman scattering measurements up to 17 GPa have been complemented with ab initio total-energy, lattice dynamics, band structure calculations. Our measurements, which include previously unreported for crystalline α-As2Te3, show that this compound undergoes reversible phase transition above 14 room temperature. The α-As2Te3 its...
In this work, we focus on the study of structural and elastic properties mercury digallium selenide (HgGa2Se4) which belongs to family AB2X4 ordered-vacancy compounds with tetragonal defect chalcopyrite structure. We have carried out high-pressure x-ray diffraction measurements up 13.2 GPa. Our been complemented compared total-energy ab initio calculations. The equation state axial compressibilities for low-pressure phase HgGa2Se4 experimentally theoretically determined other related...
High-pressure powder X-ray diffraction and Raman scattering measurements in cubic bixbyite-type indium oxide (c-In2O3) have been performed at room temperature. On increasing pressure c-In2O3 undergoes a transition to the Rh2O3–II structure but on decreasing Rh2O3–II-type In2O3 previously unknown phase with Pbca space group which is isostructural Rh2O3–III. further decrease of pressure, we observed metastable corundum-type near conditions. Recompression temperature leads Rh2O3–III phase, thus...
Compresed BiTeBr has been studied from a joint experimental and theoretical perspective. Room-temperature x-ray diffraction, Raman scattering, transport measurements at high pressures have performed in this layered semiconductor interpreted with the help of ab initio calculations. A reversible first-order phase transition observed above 6--7 GPa, but changes structural, vibrational, electrical properties also noted near 2 GPa. Structural vibrational are likely due to hardening interlayer...
We report a joint experimental and theoretical study of the structural, vibrational, electronic properties layered monoclinic arsenic sulfide (alpha-As2S3), aka mineral orpiment, under compression. X-ray diffraction Raman scattering measurements performed in orpiment samples at high pressure combined with ab initio calculations have allowed us to determine equation state tentative assignment symmetry many Raman-active modes orpiment. From our results, we conclude that no first-order phase...
In this work, we report on high-pressure Raman scattering measurements in mercury digallium sulfide (HgGa2S4) with defect chalcopyrite structure that have been complemented lattice dynamics ab initio calculations. Our evidence semiconductor exhibits a pressure-induced phase transition from the completely ordered to partially disordered stannite above 18 GPa which is prior rocksalt 23 GPa. Furthermore, zincblende observed below 5 after decreasing pressure 25 The undergoes reversible sequence...
High-pressure Raman scattering measurements have been performed in wulfenite (PbMoO4) for both bulk and nanocrystalline powders up to 22 GPa. Our evidence the phase transition from tetragonal scheelite structure monoclinic M-fergusonite above 10.8 13.4 GPa, respectively. The pressure dependences of active modes structures were compared discussed based on our theoretical results obtained lattice dynamics ab initio calculations.
The structural properties of Thallium (III) oxide (Tl2O3) have been studied both experimentally and theoretically under compression at room temperature. X-ray powder diffraction measurements up to 37.7 GPa complemented with ab initio total-energy calculations. equation state Tl2O3 has determined compared related compounds. It found that remains in its initial cubic bixbyite-type structure 22.0 GPa. At this pressure, the onset amorphization is observed, being sample fully amorphous 25.2...