A5049357016- High-pressure geophysics and materials
- Crystal Structures and Properties
- X-ray Diffraction in Crystallography
- Crystallization and Solubility Studies
- Luminescence Properties of Advanced Materials
- Advanced Condensed Matter Physics
- Solid-state spectroscopy and crystallography
- Nuclear materials and radiation effects
- Electronic and Structural Properties of Oxides
- Rare-earth and actinide compounds
- Chalcogenide Semiconductor Thin Films
- Inorganic Fluorides and Related Compounds
- Geological and Geochemical Analysis
- 2D Materials and Applications
- Inorganic Chemistry and Materials
- Catalysis and Oxidation Reactions
- Advanced Chemical Physics Studies
- Crystallography and molecular interactions
- Boron and Carbon Nanomaterials Research
- Gas Sensing Nanomaterials and Sensors
- ZnO doping and properties
- Magnetic and transport properties of perovskites and related materials
- Thermal Expansion and Ionic Conductivity
- Glass properties and applications
- Perovskite Materials and Applications
Universitat de València
2016-2025
Instituto de Ciencia de Materiales de Sevilla
2024-2025
Tenaris (Argentina)
2024
University of Abou Bekr Belkaïd
2023
Los Alamos National Laboratory
2021
University of Salford
2021
Bhabha Atomic Research Centre
2011-2020
Fundación General
2008-2020
Homi Bhabha National Institute
2020
UNSW Sydney
2018
We have carried out optical-absorption and reflectance measurements at room temperature in single crystals of AWO4 tungstates (A=Ba, Ca, Cd, Cu, Pb, Sr, Zn). From the experimental results their band-gap energy has been determined to be 5.26 eV (BaWO4), 5.08 (SrWO4), 4.94 (CaWO4), 4.15 (CdWO4), 3.9–4.4 (ZnWO4), 3.8–4.2 (PbWO4), 2.3 (CuWO4). The are discussed terms electronic structure studied tungstates. It found that those compounds where only s electron states A2+ cation hybridize with O 2p...
We report diffuse reflectivity measurements in InNbO4, ScNbO4, YNbO4, and eight rare-earth niobates. A comparison with established values of the bandgap InNbO4 ScNbO4 shows that Tauc plot analysis gives erroneous estimates energy. Conversely, accurate results are obtained considering excitonic contributions using Elliot-Toyozawa model. The bandgaps 3.25 eV for CeNbO4, 4.35 LaNbO4, 4.5 4.73-4.93 SmNbO4, EuNbO4, GdNbO4, DyNbO4, HoNbO4, YbNbO4. fact energy is affected little by substitution...
The challenges imposed by climate change require the continued improvement and identification of materials for development green technologies. Point defect engineering is a promising technology producing hydrogen taking advantage catalytic evolution reactions. In this work, we investigate role anionic cationic vacancy point defects, as well nature active sites, in activation ${\mathrm{Cu}}_{2}{\mathrm{WS}}_{4}$ single layers. stability pristine defective structures has been thoroughly...
Platinum is one of the most important technological materials, and studied transition metals. Yet, its phase diagram remains virtually unknown. The solid Pt at ambient conditions face-centered cubic (fcc). However, in a previous paper [L. Burakovsky et al., J. Phys. Conf. Ser. 500, 162001 (2014)], we predicted to undergo transformation from fcc another phase, namely, randomly disordered hexagonal close-packed (hcp) or simply random hcp (rhcp), which spans pressure interval ∼35–300 GPa exists...
We report high-pressure measurements for the melting curve of Ti, V, Cr, Mo, Ta, W, Fe, Co, and Ni. Measurements were made in a laser-heated diamond-anvil-cell to nearly 100 GPa 4000 K. The bcc metals have surprisingly small slopes which approach zero at high pressure. curves Ni, Fe are parallel. Several ab-initio calculations incompatible with present results.
The melting curve of Mg, Mn, Cu, Ag, Au, Zn, Cd, Al, In, and Pb has been measured up to 12 GPa using a Bridgman-type cell. Melting at high-pressure was identified detecting discontinuities in the electrical resistance studied metals. results are compared with previous experimental theoretical studies when possible. A comparison Lindemann’s law predictions is also done. In particular we found that among metals steepest (dTM/dP=78 K/GPa). contrast, Mn flattest (dTM/dP=29 reported suggest...
Angle-dispersive x-ray diffraction (ADXRD) and absorption near edge structure (XANES) measurements have been performed in the AWO4 tungstates CaWO4 SrWO4 under high pressure up to approximately 20 GPa. Similar phase transitions transition pressures observed for both using two techniques studied range. Both materials are found undergo a pressure-induced scheelite-to-fergusonite sufficiently hydrostatic conditions. Our results compared those previously literature supported by ab initio total...
The electronic environment of the Fe nuclei in two silicate perovskite samples, Fe0.05Mg0.95SiO3 (Pv05) and Fe0.1Mg0.9SiO3 (Pv10), have been measured to 120 GPa 75 GPa, respectively, at room temperature using diamond anvil cells synchrotron Mössbauer spectroscopy (SMS). Such investigations extremely small dilute 57Fe-bearing samples become possible through development SMS. Our results are explained framework "three-doublet" model, which assumes Fe2+-like sites one Fe3+-like site that well...
The electronic structure of four ternary-metal oxides containing isolated vanadate ions is studied. Zircon-type YVO4, YbVO4, LuVO4, and NdVO4 are investigated by high-pressure optical-absorption measurements up to 20 GPa. First-principles calculations based on density-functional theory were also performed analyze the band as a function pressure. near Fermi level originates largely from molecular orbitals ion, but cation substitution influence these states. studied ortovanadates, with...
High-pressure x-ray diffraction studies on vaterite-type borates were reported the above paper and their room-temperature P-V equation of state (EOS) determined. YBO3/Eu3+ GdBO3 found to have bulk moduli around 320 GPa, 90% larger than modulus obtained for EuBO3. Consequently, it was stated that are as incompressible cubic BN. Such a different compressional behavior isomorphic contradicts known systematic related borates. Here, we show conclusions article could be hindered by experimental...
Room temperature angle-dispersive x-ray diffraction measurements on zircon-type YPO4 and ErPO4, monazite-type GdPO4, EuPO4, NdPO4, LaPO4 were performed in a diamond-anvil cell up to 27 GPa using neon as pressure-transmitting medium. In the zircon-structured oxides we found evidence of reversible pressure-induced structural phase transformation from zircon structure. The onset transition is near 17-20 GPa. non-reversible around 26 GPa, being barite-type structure proposed for high-pressure...
Melting curves of Cu, Ni, Pd, and Pt were measured in a laser-heated diamond-anvil cell up to 43, 52, 28, 28 GPa, respectively. The obtained results are compared with previous studies. In particular, the measurements made Cu agreement literature. experiments consistent $Z$ method calculations indicating that earlier probably underestimate melting temperature at high pressure. show qualitative similar behavior. case confirm it has low slope K/GPa. Ni is only transition metal groups 10 11...
The electronic band-structure and band-gap dependence on the $d$ character of ${A}^{2+}$ cation in $A$WO${}_{4}$ wolframite-type oxides is investigated for different compounds ($A$ $=$ Mg, Zn, Cd, Mn) by means optical-absorption spectroscopy first-principles density-functional calculations. High pressure used to tune their properties up 10 GPa changing bonding distances establishing structural correlations. effect unfilled levels found produce changes nature band gap as well its without...
Current interest in barocaloric effects has been stimulated by the discovery that these pressure-driven thermal changes can be giant near ferroic phase transitions materials display magnetic or electrical order. Here we demonstrate inverse solid electrolyte AgI, its superionic transition at ~420 K. Over a wide range of temperatures, hydrostatic pressure 2.5 kbar yield large and reversible effects, resulting values refrigerant capacity. Moreover, peak isothermal entropy change (60 J K-1 kg-1...
The phase diagram of magnesium has been investigated to 211 GPa at 300 K, and 105 4500 by using a combination x-ray diffraction resistive laser heating. ambient pressure hcp structure is found start transforming the bcc $\ensuremath{\sim}45$ GPa, with large region phase-coexistence that becomes smaller higher temperatures. stable highest pressures reached. hcp-bcc boundary studied on both compression decompression, its slope be negative steeper than calculations have previously predicted....
The crystal structures, lattice vibrations, and electronic band structures of PbCrO4, PbSeO4, SrCrO4, SrSeO4 were studied by ab initio calculations, Raman spectroscopy, X-ray diffraction, optical-absorption measurements. Calculations properly describe the four compounds, which are isomorphic to monazite structure confirmed diffraction. Information is also obtained on Raman- IR-active phonons, with all vibrational modes assigned. In addition, densities states compounds determined. All...
The 5d transition metals have attracted specific interest for high-pressure studies due to their extraordinary stability and intriguing electronic properties. In particular, iridium metal has been proposed exhibit a recently discovered pressure-induced transition, the so-called core-level crossing at lowest pressure among all metals. Here, we report an experimental structural characterization of by x-ray probes sensitive both long- short-range order in matter. Synchrotron-based powder...
Abstract In this work, the melting line of platinum has been characterized both experimentally, using synchrotron X-ray diffraction in laser-heated diamond-anvil cells, and theoretically, ab initio simulations. investigated pressure temperature range (pressure between 10 GPa 110 300 K 4800 K), only face-centered cubic phase observed. The points obtained with two techniques are good agreement. Furthermore, results agree considerably extend previously large-volume devices one cells experiment,...
Abstract Compared to other body-centered cubic (bcc) transition metals, Nb has been the subject of fewer compression studies and there are still aspects its phase diagram which unclear. Here, we report a combined theoretical experimental study under high pressure temperature. We present results static laser-heated diamond anvil cell experiments up 120 GPa using synchrotron-based fast x-ray diffraction with ab initio quantum molecular dynamics simulations. The melting curve is determined...
Variegation is a rare type of mosaicism not fully studied in plants, especially fruits. We examined red and white sections grape (Vitis vinifera cv. 'Béquignol') variegated berries found that accumulation products from branches the phenylpropanoid isoprenoid pathways showed an opposite tendency. Light-responsive flavonol monoterpene levels increased anthocyanin-depleted areas correlation with increasing MYB24 expression. Cistrome analysis suggested binds to promoters 22 terpene synthase...
Finding green energy resources that contribute to the battle against global warming and pollution of our planet is an urgent challenge. Thermoelectric electricity production a clean efficient method producing energy; consequently, scientists are currently researching creating thermoelectric materials increase efficiency expand potential effect for production. This work focuses on comprehensive study properties two-dimensional ScYCBr2. We report here computational analysis this Janus-like...