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141 results on '"Gonzalez-Platas, Javier"'

1. Revisiting the pressure-induced phase transitions of Methylammonium Lead Bromide Perovskite

Author

Liang, Akun, Gonzalez-Platas, Javier, Turnbull, Robin, Popescu, Catalin, Fernandez-Guillen, Ismael, Abargues, Rafael, Boix, Pablo P., Shi, Lan-Ting, and Errandonea, Daniel

Subjects
Condensed Matter - Materials Science
Abstract

The high-pressure crystal structure evolution of CH3NH3PbBr3 (MAPbBr3) perovskite has been investigated by single-crystal X-ray diffraction and synchrotron-based powder X-ray diffraction. Single-crystal X-ray diffraction reveals that the crystal structure of MAPbBr3 undergoes two phase transitions following the space-group sequence: Pm-3m-to-Im3-to-Pmn21. The transitions take place at around 0.8 and 1.8 GPa, respectively. This result is contradicting the previously reported phase transition sequence: Pm-3m-to-Im3-to-Pnma. In this work the crystal structures of each of the three phases are determined from single-crystal X-ray diffraction analysis which is later supported by Rietveld refinement of powder X-ray diffraction patterns. The pressure dependence of the crystal lattice parameters and unit-cell volumes are determined from the two aforementioned techniques, as well as the bulk moduli for each phase. The bandgap behaviour of MAPbBr3 has been studied up to around 4 GPa, by the means of single-crystal optical-absorption experiments. The evolution of the bandgap has been well explained using the pressure dependence of the Pb-Br bond distance and Pb-Br-Pb angles as determined from single-crystal X-ray diffraction experiments., Comment: 20 pages, 5 pages

Published
2024
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3. Extension of Hall-symbols of crystallographic space groups to magnetic space groups

Author

González-Platas, Javier, Katcho, Nebil A., and Rodríguez-Carvajal, Juan

Subjects
Condensed Matter - Materials Science
Abstract

The Hall-symbols for describing unambiguously the generators of space groups have been extended to describe whatever setting of the 1651 types of magnetic space groups (Shubnikov groups). A computer program called MHALL has been developed for parsing the Hall symbols, generate the full list of symmetry operators and identify the transformation to the standard setting.

Published
2020

8. Polymorphism and Phase Stability of Hydrated Magnesium Carbonate Nesquehonite MgCO3·3H2O: Negative Axial Compressibility and Thermal Expansion in a Cementitious Material

Author

Santamaría-Pérez, David, primary, Chuliá-Jordán, Raquel, additional, Gonzalez-Platas, Javier, additional, Otero-de-la-Roza, Alberto, additional, Ruiz-Fuertes, Javier, additional, Pellicer-Porres, Julio, additional, Oliva, Robert, additional, and Popescu, Catalin, additional

Published
2024
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10. 2D Cu(I)-I Coordination Polymer with Smart Optoelectronic Properties and Photocatalytic Activity as a Versatile Multifunctional Material

Author

Murillo, María, primary, Wannemacher, Reinhold, additional, Cabanillas-González, Juan, additional, Rodríguez-Mendoza, Ulises R., additional, Gonzalez-Platas, Javier, additional, Liang, Akun, additional, Turnbull, Robin, additional, Errandonea, Daniel, additional, Lifante-Pedrola, Ginés, additional, García-Hernán, Andrea, additional, Martínez, Jose I., additional, and Amo-Ochoa, Pilar, additional

Published
2023
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12. 2D Cu(I)-I Coordination Polymer with Smart Optoelectronic Properties and Photocatalytic Activity as a Versatile Multifunctional Material

Author

Murillo, María, Wannemacher, Reinhold, Cabanillas-González, Juan, Rodríguez-Mendoza, Ulises R., Gonzalez-Platas, Javier, Liang, Akun, Turnbull, Robin, Errandonea, Daniel, Lifante-Pedrola, Ginés, García-Hernán, Andrea, Martínez, José I., Amo-Ochoa, Pilar, Murillo, María, Wannemacher, Reinhold, Cabanillas-González, Juan, Rodríguez-Mendoza, Ulises R., Gonzalez-Platas, Javier, Liang, Akun, Turnbull, Robin, Errandonea, Daniel, Lifante-Pedrola, Ginés, García-Hernán, Andrea, Martínez, José I., and Amo-Ochoa, Pilar

Abstract

This work presents two isostructural Cu(I)-I 2-fluoropyrazine (Fpyz) luminescent and semiconducting 2D coordination polymers (CPs). Hydrothermal synthesis allows the growth of P-1 space group single crystals, whereas solvent-free synthesis produces polycrystals. Via recrystallization in acetonitrile, P21 space group single crystals are obtained. Both show a reversible luminescent response to temperature and pressure. Structure determination by single-crystal X-ray diffraction at 200 and 100 K allows us to understand their response as a function of temperature. Applying hydrostatic/uniaxial pressure or grinding also generates significant variations in their emission. The high structural flexibility of the Cu(I)-I chain is significantly linked to the corresponding alterations in structure. Remarkably, pressure can increase the conductivity by up to 3 orders of magnitude. Variations in resistivity are consistent with changes in the band gap energy. The experimental results are in agreement with the DFT calculations. These properties may allow the use of these CPs as optical pressure or temperature sensors. In addition, their behavior as a heterogeneous photocatalyst of persistent organic dyes has also been investigated.

Published
2023

13. Joint experimental and theoretical study of PbGa2S4 under compression.

Author

Garcia-Sanchez, Tania, Gallego-Parra, Samuel, Liang, Akun, Rodrigo-Ramon, José Luis, Muñoz, Alfonso, Rodriguez-Hernandez, Plácida, Gonzalez-Platas, Javier, Sans, Juán Ángel, Cuenca-Gotor, Vanesa Paula, Osman, Hussien H., Popescu, Catalin, Ursaki, Veaceslav, Tiginyanu, Ion M., Errandonea, Daniel, and Manjón, Francisco Javier

Abstract

The effect of pressure on the structural, vibrational, and optical properties of lead thiogallate, PbGa2S4, crystallizing under room conditions in the orthorhombic EuGa2S4-type structure (space group Fddd), is investigated. The results from X-ray diffraction, Raman scattering, and optical-absorption measurements at a high pressure beyond 20 GPa are reported and compared not only to ab initio calculations, but also to the related compounds α′-Ga2S3, CdGa2S4, and HgGa2S4. Evidence of a partially reversible pressure-induced decomposition of PbGa2S4 into a mixture of Pb6Ga10S21 and Ga2S3 above 15 GPa is reported. Thus, our measurements and calculations show a route for the high-pressure synthesis of Pb6Ga10S21, which is isostructural to the stable Pb6In10S21 compound at room pressure. [ABSTRACT FROM AUTHOR]

Published
2023
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15. Joint experimental and theoretical study of PbGa2S4 under compression

Author

Garcia-Sanchez, Tania, primary, Gallego-Parra, Samuel, additional, Liang, Akun, additional, Rodrigo-Ramon, José Luis, additional, Muñoz, Alfonso, additional, Rodriguez-Hernandez, Plácida, additional, Gonzalez-Platas, Javier, additional, Sans, Juán Ángel, additional, Cuenca-Gotor, Vanesa Paula, additional, Osman, Hussien H., additional, Popescu, Catalin, additional, Ursaki, Veaceslav, additional, Tiginyanu, Ion M., additional, Errandonea, Daniel, additional, and Manjón, Francisco Javier, additional

Published
2023
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30. Equation of state and structural characterization of Cu4I4{PPh2(CH2CH = CH2)}4 under pressure

Author

Amagoia Aguirrechu-Comerón, Rodríguez-Hernández, Plácida, Rodríguez-Mendoza, Ulises R., Vallcorba, Oriol, Muñoz, Alfonso, Perruchas, Sandrine, and Gonzalez-Platas, Javier

Abstract

Combined high pressure single crystal X-ray diffraction experiments and ab initio simulations based on the density functional theory have been performed on a copper(I) iodide cluster formulated [Cu4I4{PPh2(CH2CH = CH2)}4] under high pressure up to 5 GPa. An exhaustive study of compressibility has been done by means of determination of isothermal equations of state and structural changes with pressure at 298 K taking advantage of the single crystal is more precise than powder X-ray diffraction for this type of experiments. It allows us to report the evidence of the existence of an isostructural phase transition of second order at 2.3 GPa not detected so far.

Published
2019
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36. Chemical Engineering of Photoactivity in Heterometallic Titanium-Organic Frameworks by Metal Doping

Author

Universitat Politècnica de València. Departamento de Química - Departament de Química, Junta de Andalucía, European Regional Development Fund, Ministerio de Economía y Competitividad, Castells-Gil, Javier, Padial, Natalia M., Almora-Barrios, Neyvis, Albero-Sancho, Josep, Ruiz-Salvador, A. Rabdel, Gonzalez-Platas, Javier, García Gómez, Hermenegildo, Marti-Gastaldo, Carlos, Universitat Politècnica de València. Departamento de Química - Departament de Química, Junta de Andalucía, European Regional Development Fund, Ministerio de Economía y Competitividad, Castells-Gil, Javier, Padial, Natalia M., Almora-Barrios, Neyvis, Albero-Sancho, Josep, Ruiz-Salvador, A. Rabdel, Gonzalez-Platas, Javier, García Gómez, Hermenegildo, and Marti-Gastaldo, Carlos

Abstract

[EN] We report a new family of titanium-organic frameworks that enlarges the limited number of crystalline, porous materials available for this metal. They are chemically robust and can be prepared as single crystals at multi-gram scale from multiple precursors. Their heterometallic structure enables engineering of their photoactivity by metal doping rather than by linker functionalization. Compared to other methodologies based on the post-synthetic metallation of MOFs, our approach is well-fitted for controlling the positioning of dopants at an atomic level to gain more precise control over the band-gap and electronic properties of the porous solid. Changes in the band-gap are also rationalized with computational modelling and experimentally confirmed by photocatalytic H-2 production.

Published
2018

39. Synthesis, reactivity, and kinetics of substitution in [W.sub.3]Pd[Se.sub.4] cuboidal clusters: a reexamination of the kinetics of substitution of the related [W.sub.3][S.sub.4] cluster with thiocyanate

Author

Algarra, Andres G., Sokolov, Maxim N., Gonzalez-Platas, Javier, Fernandez-Trujillo, Maria Jesus, Basallote, Manuel G., and Hernandez-Molina, Rita

Subjects
Palladium catalysts -- Chemical properties, Palladium catalysts -- Structure, Selenium compounds -- Chemical properties, Selenium compounds -- Structure, Thiocyanates -- Chemical properties, Thiocyanates -- Structure, X-rays -- Diffraction, X-rays -- Usage, Chemistry
Published
2009

40. Equation of state and structural characterization of Cu4I4{PPh2(CH2CH = CH2)}4 under pressure.

Author

Aguirrechu-Comerón, Amagoia, Rodríguez-Hernández, Plácida, Rodríguez-Mendoza, Ulises R., Vallcorba, Oriol, Muñoz, Alfonso, Perruchas, Sandrine, and Gonzalez-Platas, Javier

Subjects
COPPER ions, EQUATIONS of state, HIGH pressure (Technology), SINGLE crystals, X-ray diffraction, DENSITY functional theory
Abstract

Combined high pressure single crystal X-ray diffraction experiments and ab initio simulations based on the density functional theory have been performed on a copper(I) iodide cluster formulated [Cu4I4{PPh2(CH2CH = CH2)}4] under high pressure up to 5 GPa. An exhaustive study of compressibility has been done by means of determination of isothermal equations of state and structural changes with pressure at 298 K taking advantage of the single crystal is more precise than powder X-ray diffraction for this type of experiments. It allows us to report the evidence of the existence of an isostructural phase transition of second order at 2.3 GPa not detected so far. [ABSTRACT FROM AUTHOR]

Published
2019
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41. Dense Hydrated Magnesium Carbonate MgCO3·3H2O Phases

Author

Botan-Neto, Benedito Donizeti, Santamaria-Perez, David, Bayarjargal, Lkhamsuren, Bykova, Elena, Gonzalez-Platas, Javier, and Otero-de-la-Roza, Alberto

Abstract

The study of the structural stability of carbonates under different pressure and temperature conditions is important for modeling the carbon budget in the Earth’s interior and the stability of carbonation products of carbon capture and storage (CCS) solutions. In this work, we confirm the existence of the two dense polymorphs of the hydrated magnesium carbonate MgCO3·3H2O nesquehonite mineral previously reported, and we characterize their structures using synchrotron single-crystal X-ray diffraction at 3.1 and 11.6 GPa. Phase transitions entail the distortion and atomic rearrangement of the Mg-centered polyhedra and the tilting of the [CO3] carbonate units. In particular, the Mg coordination number increases from 6 in nesquehonite to 7 in the second high-pressure phase, while maintaining a topology based on complex MgCO3(H2O)2chains. We also studied their vibrational behavior upon compression using Raman spectroscopy and complemented the experimental results with density-functional theory (DFT) calculations. The role played by hydrogen bonds in the compressibility and the polymorphism of this hydrated carbonate is also discussed.

Published
2024
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42. Experimental and ab Initio Study of Catena(bis(μ2-iodo)-6-methylquinoline-copper(I)) under Pressure: Synthesis, Crystal Structure, Electronic, and Luminescence Properties

Author

Aguirrechu-Comerón, Amagoia, primary, Hernández-Molina, Rita, additional, Rodríguez-Hernández, Plácida, additional, Muñoz, Alfonso, additional, Rodríguez-Mendoza, Ulises R., additional, Lavín, Vı́ctor, additional, Angel, Ross J., additional, and Gonzalez-Platas, Javier, additional

Published
2016
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50. Synthesis, structure and NMR studies of trinuclear Mo3S4 clusters coordinated with dithiophosphate and chiral carboxylate ligands.

Author

Gushchin, Artem L., Hernandez-Molina, Rita, Anyushin, Alexander V., Gallyamov, Marsel R., Gonzalez-Platas, Javier, Moroz, Nikolay K., and Sokolov, Maxim N.

Subjects
CHIRALITY, STEREOCHEMISTRY, CHIRALITY element, LIGAND exchange reactions, LIGANDS (Chemistry)
Abstract

New chiral cluster complexes containing (S)-mandelate and (S)-phenyllactate ligands, [Mo3S4(dtp)3(μ-(S)-mandelate)(py)] (1) and [Mo3S4(dtp)3(μ-(S)-phenyllactate)(py)], were prepared from [Mo3S4(dtp)3(μ-dtp)(H2O)] (dtp = (EtO)2PS2) by ligand substitution. The crystal structures of 1 and 2 were determined by X-ray diffraction. Detailed variable-temperature 31P{1H} and 1H NMR studies of solutions of 1 and 2 in non-coordinating solvents (CDCl3, CD2Cl2) demonstrated three dynamic processes at the Mo–Py coordination site: diastereomer interconversion [(PS) to (MS)] which is inhibited at low temperatures; pyridine rotation around the Mo–py bond (180°-flip), and pyridine exchange in the presence of added pyridine. Activation parameters for all exchange processes have been estimated. [ABSTRACT FROM AUTHOR]

Published
2016
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