A5060967129- Magnetic and transport properties of perovskites and related materials
- Advanced Condensed Matter Physics
- Multiferroics and related materials
- Crystallization and Solubility Studies
- X-ray Diffraction in Crystallography
- Perovskite Materials and Applications
- Solid-state spectroscopy and crystallography
- Ferroelectric and Piezoelectric Materials
- Dielectric properties of ceramics
- Electrocatalysts for Energy Conversion
- Advancements in Solid Oxide Fuel Cells
- Thermal Expansion and Ionic Conductivity
- Nuclear materials and radiation effects
- Microwave Dielectric Ceramics Synthesis
- Advanced battery technologies research
- Crystallography and molecular interactions
- Gas Sensing Nanomaterials and Sensors
- Catalytic Processes in Materials Science
- Catalysis and Oxidation Reactions
- Electronic and Structural Properties of Oxides
- Advanced Thermoelectric Materials and Devices
- Zeolite Catalysis and Synthesis
- Advanced Photocatalysis Techniques
- Optical and Acousto-Optic Technologies
- Cloud Data Security Solutions
Instituto de Ciencia de Materiales de Madrid
2011-2024
Universidad Complutense de Madrid
2024
University of Edinburgh
2018-2023
International Council on Mining and Metals
2023
Consejo Superior de Investigaciones Científicas
2012-2021
The University of Sydney
2015-2020
The King's College
2018
Institut de Recerca en Energia de Catalunya
2015
Université de Bordeaux
1990
Proton exchange membrane water electrolysis is a promising technology to produce green hydrogen from renewables, as it can efficiently achieve high current densities. Lowering iridium amount in oxygen evolution reaction electrocatalysts critical for achieving cost-effective production of hydrogen. In this work, we develop catalysts Ir double perovskites. Sr
Element- and orbital-selective x-ray absorption magnetic circular dichroism measurements are carried out to probe the electronic structure magnetism of Ir $5d$ states in double perovskite ${\mathrm{Sr}}_{2}{M\text{IrO}}_{6}$ ($M=\mathrm{Mg}$, Ca, Sc, Ti, Ni, Fe, Zn, In) ${\mathrm{La}}_{2}{\mathrm{NiIrO}}_{6}$ compounds. All studied systems present a significant influence spin-orbit interactions ground state. In addition, we find that local moment shows different character depending on...
The large-scale deployment of polymer electrolyte water electrolysis (PEWE) is largely limited by the use O2 evolution reaction (OER) catalysts based on scarce and expensive iridium in PEWE anodes. ensuing need for better-performing, Ir-based OER requires an improved understanding relation between these materials' activity their physicochemical operando properties. To shed light this matter, here, we employed modulation excitation X-ray absorption spectroscopy to determine oxidation state...
Hybrid organic-inorganic perovskites, MAPbX3 (X= halogen), containing methylammonium (MA: CH3-NH3+) in the large voids conformed by PbX6 octahedral network, are active absorption materials new generation of solar cells. CH3NH3PbBr3 is a promising alternative with band-gap that gives rise to high open circuit voltage. A deep knowledge crystal structure and, particular, MA conformation inside perovskite cage across phase transitions undergone below room temperature, seems essential establish...
In view of iridium's scarceness and high cost, Ir-containing catalysts for water electrolyzers should have low loadings maximal utilization.
This work reports a family of Ru-based perovskites for acid OER. Dy 2 NiRuO 6 displays the highest activity and stability more than 400 OER cycles. Its high is related to short Ru–O bonds surface local ratio Ni : Ru close 1 1.
Double perovskites containing Ir(6+)/Ir(5+) with formula Sr2MIrO6 (M = Ni, Zn) have been synthesized under high oxygen pressure conditions. Their crystal structures studied by X-ray and neutron powder diffraction at room temperature (RT) 2 K. At RT, these oxides crystallize in the monoclinic space group P2(1)/n unit-cell parameters a ≈ √2a0, b c 2a0, β 90°. The thermal evolution of structure Ni-containing compound shows presence two phase transition 373-673 K interval following sequence →...
The crystal structures of the series ordered double perovskites Ba(2-x)Sr(x)YIrO6 (0 ≤ x 2) were refined using a combination high-resolution synchrotron X-ray and high-intensity neutron diffraction data. materials displayed sequence Fm3̅m(a(0)a(0)a(0)) (x = 0.6)--> I4/m(a(0)a(0)c(-)) 1.0)--> I2/m(a(-)a(-)c(0)) 1.4)--> P2(1)/n(a(-)a(-)c(+)) associated with increased tilting corner-sharing octahedra induced by increasing amount smaller Sr cation present. A similar transitions was heating...
Abstract Sr 2 CaIrO 6 and MgIrO double perovskites have been prepared as polycrystalline powders from citrate precursors treated under oxygen pressure conditions. These compounds studied by X‐ray neutron powder diffraction (NPD), magnetic measurements, absorption spectroscopy. The crystal symmetry of both oxides is monoclinic (space group P2 1 / n ), the unit‐cell parameters are related to ideal simple perovskite cell a ≈ √2 0 , b c β 90°, where edge cubic ABO 3 perovskite. This...
We report the occurrence of a magnetodielectric effect and its correlation with structure magnetism in $A$-site ordered chromate spinel oxides $\mathrm{Li}M\mathrm{C}{\mathrm{r}}_{4}{\mathrm{O}}_{8}$ ($M=\mathrm{Ga}$, In). In addition to magnetic dielectric measurements, temperature dependent synchrotron neutron diffraction experiments have been carried out for Ga compound. The results are compared contrasted that corresponding conventional $B$-site oxide,...
The structural and magnetic properties of the two Ir(V) perovskites Ba2ScIrO6 Sr2ScIrO6 were established. structures refined using a combined neutron synchrotron data set. At room temperature former has cubic structure in space group Fm3̅m with = 8.1450(3) Å, latter is monoclinic P21/n 5.6606(3) b 5.6366(3) c 7.9720(4) β 89.977(5)°. Magnetization measurements show both oxides have moments close to zero as consequence strong spin-orbit coupling that results Jeff ≈ 0 ground state. distortion...
Ruthenium-containing double perovskites A2ScRuO6 have been synthesized as polycrystalline powders and structurally characterized using a combination of synchrotron X-ray neutron powder diffraction methods. When A = Ba, hexagonal 6L perovskite structure is obtained if the synthesis conducted at ambient pressure rock-salt ordered cubic sample quenched from high pressures. The Sr oxide Sr2ScRuO6 with corner sharing topology. Heat capacity bulk magnetic susceptibility measurements show that...
Abstract The preparation, crystal structure and magnetic properties of Sr 2 BIrO 6 (B = In, Sc, Fe, Co or Ti) oxides are reported. For B In materials, X‐ray neutron powder diffraction (NPD) studies confirm the presence 1:1 B‐ordered perovskite‐like structures crystallizing in monoclinic I 2/ m P 1 / n space groups, with unit‐cell parameters a ≈ √2 0 , b c β 90°. TiIrO is described as disordered perovskite orthorhombic symmetry Pbnm group. Fe Co, low‐temperature NPD data measurements indicate...
Iridates having pentavalent Ir${}^{5+}$ ions have emerged in the last years as an exciting playground to tune atomic magnetic ground state from nonmagnetic $J=$0 $J\ensuremath{\ne}$0 by either distortions of IrO${}_{6}$ octahedra or increased orbital overlap. Here, authors analyze origin response observed Sr${}_{2}$YIrO${}_{6}$ and reveal that this case neither volume contraction nor structural are sufficient cause any change ions.
From the cubic phase at RT, three superstructures are identified down to 120 K result from octahedral SnBr<sub>6</sub> tilting and stereochemical effect of Sn<sup>2+</sup> lone pair. The Seebeck coefficient is ∼2000 μV K<sup>−1</sup> RT.
Double perovskites containing Ir4+ were synthesised by a citrate technique, followed an annealing treatment in air at 1100 °C. The crystal structure of the three compounds, with formula R2NiIrO6 (R= La, Pr and Nd), determined using combined refinement against neutron powder diffraction (NPD) synchrotron x-ray (SXRPD) data sets. At room temperature, all samples indexed space group P21/n monoclinic symmetry remains 300 to 1273 K temperature range. Magnetization measurements suggest competitive...
The crystal and magnetic structures of double perovskites the type Ba2-xSrxYOsO6 were studied by synchrotron X-ray neutron powder diffraction methods, bulk susceptibility measurements, absorption spectroscopy. refined using combined data sets based on an ordered array corner-sharing YO6 OsO6 octahedra, with Ba/Sr cations being completely disordered. structure evolves from cubic to monoclinic Fm3̅m (x ≈ 0.6) → I4/m 1.0) I2/m 1.6) P21/n as Sr content is increased, due introduction cooperative...
A simple crossover from two-dimensional to three-dimensional correlated disorder of O and N atoms on a cubic lattice has been discovered within the Ba1-xSrxTaO2N series perovskite oxynitrides. The is driven by expansion as x decreases, provides rapid increase in entropy due change subextensive extensive configurational regimes.
We report on zone center terahertz excitations of non-Jahn Teller ${\mathrm{LaFeO}}_{3}, {\mathrm{PrFeO}}_{3}, {\mathrm{ErFeO}}_{3}$, and ${\mathrm{LuFeO}}_{3}$ distorted perovskites under external magnetic fields up 7 T. Our measurements low-temperature/low-energy absorptions ${\mathrm{LaFeO}}_{3}$ show quasiantiferromagnetic (q-AFM) quasiferromagnetic (q-FM) magnons at...
The A-site ordered perovskite oxide CdCu3Mn4O12 has been synthesized for the first time in polycrystalline form under high pressure (7 GPa) and temperature (1000 °C) conditions, required to stabilize small Cd Cu cations at A positions of perovskite. crystal structure studied by X-ray powder diffraction room temperature. This crystallizes cubic space group Im3̅ (no. 204) with unit-cell parameter a = 7.2179(5) Å 300 K. MnO6 network is extremely tilted, giving rise square planar coordination...
The temperature dependences of the structures three polytypes BaRuO<sub>3</sub> have been investigated between room and 1000 °C using high resolution synchrotron X-ray diffraction.