Author: Ulises R. Rodríguez-mendoza

Smart composite films of nanometric thickness based on copper-iodine coordination polymers. Toward sensors.

2018

One-pot reactions between CuI and methyl or methyl 2-amino-isonicotinate give rise to the formation of two coordination polymers (CPs) based on double zig-zag Cu2I2 chains. The presence of a NH2 group in the isonicotinate ligand produces different supramolecular interactions affecting the Cu-Cu distances and symmetry of the Cu2I2 chains. These structural variations significantly modulate their physical properties. Thus, both CPs are semiconductors and also show reversible thermo/mechanoluminescence. X-ray diffraction studies carried out under different temperature and pressure conditions in combination with theoretical calculations have been used to rationalize the multi-stimuli-responsive …

Materials scienceFabricationPolymersThin filmsComposite numberSupramolecular chemistryNanocomposite films02 engineering and technologyOptoelectronic devices010402 general chemistry01 natural sciencesNanomaterialschemistry.chemical_classificationFilm thicknessChainsNanostructured materialsQuímicaGeneral ChemistryPolymerBinary alloys021001 nanoscience & nanotechnology0104 chemical sciencesChemistrychemistryChemical engineeringNanofiberNanometreFilm preparationSupramolecular chemistry0210 nano-technologyCoordination reactionsNanofibresCopperMechanoluminescenceIodineChemical science

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Formation of nanostructures in Eu3+ doped glass-ceramics: an XAS study.

2012

We describe the results of x-ray absorption experiments carried out to deduce structural and chemical information in Eu(3+) doped, transparent, oxyfluoride glass and nanostructured glass-ceramic samples. The spectra were measured at the Pb and Eu-L(III) edges. The Eu environment in the glass samples is observed to be similar to that of EuF(3). Complementary x-ray diffraction experiments show that thermal annealing creates β-PbF(2) type nanocrystals. X-ray absorption indicates that Eu ions act as seeds in the nanocrystal formation. There is evidence of interstitial fluorine atoms around Eu ions as well as Eu dimers. X-ray absorption at the Pb-L(III) edge shows that after the thermal treatmen…

X-ray absorption spectroscopyCeramicsMaterials scienceNanostructureDopingMolecular ConformationMineralogyThermal treatmentCondensed Matter PhysicsSpectral linePhase TransitionNanostructuresX-Ray Absorption SpectroscopyNanocrystalEuropiumvisual_artMaterials Testingvisual_art.visual_art_mediumPhysical chemistryGeneral Materials ScienceCeramicGlassAbsorption (chemistry)Particle SizeCrystallizationJournal of physics. Condensed matter : an Institute of Physics journal

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Experimental and theoretical study on the optical properties of LaVO4 crystals under pressure

2018

We report optical absorption and luminescence measurements in pure and trivalent neodymium (Nd3+) doped LaVO4 crystals up to 25 GPa. Nd3+ luminescence has been employed as a tool to follow the structural changes in the crystal. We also present band-structure and crystal-field calculations that provide the theoretical framework to accurately explain the observed experimental results. In particular, both optical absorption and luminescence measurements evidence that a phase transition takes place close to 12 GPa. They also provide information on the pressure dependence of the band-gap as well as the emission lines under compression. We found drastic changes in the optical properties of LaVO4 …

Phase transitionMaterials scienceCoordination numberPhysics::OpticsGeneral Physics and Astronomychemistry.chemical_element02 engineering and technologyZIRCON-TYPE LAVO4010402 general chemistry01 natural sciencesNeodymiumMolecular physicsCrystalsymbols.namesakeEU3+ IONSEmission spectrumPhysical and Theoretical ChemistryAbsorption (electromagnetic radiation)AB-INITIO021001 nanoscience & nanotechnologyRARE-EARTH IONS0104 chemical scienceschemistrysymbolsZIRCON-TYPE LAVO4 RARE-EARTH IONS AB-INITIO EU3+ IONS0210 nano-technologyLuminescenceRaman spectroscopy

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Lanthanide-doped Y3Ga5O12 garnets for nanoheating and nanothermometry in the first biological window

2018

Abstract Absorption and luminescence spectra in the first biological window of Nd3+ single-doped and Er3+-Yb3+ co-doped Y3Ga5O12 nano-garnets have been studied to evaluate their potential use as simultaneous optical nanoheaters and nanothermometers in biomedicine. Nd3+-doped nano-garnets uses the 808 nm laser radiation, resonant with the largest absorption peak of the 4I9/2 → 4F5/2 transition, for both heating the nanoparticle and populating the 4F3/2 emitting level. Changes in the relative intensities of different emission peaks between Stark levels of the 4F3/2 (R1,2)→4I9/2 (Z1-5) transition can be directly related to the temperature of the nano-garnet. On the other hand, the Yb3+/Er3+com…

LanthanideMaterials scienceOrganic ChemistryDopingNanoparticle02 engineering and technologyRadiation010402 general chemistry021001 nanoscience & nanotechnologyLaser01 natural sciencesAtomic and Molecular Physics and OpticsPhoton upconversion0104 chemical sciencesElectronic Optical and Magnetic MaterialsIonlaw.inventionInorganic ChemistrylawElectrical and Electronic EngineeringPhysical and Theoretical ChemistryAtomic physics0210 nano-technologyAbsorption (electromagnetic radiation)SpectroscopyOptical Materials

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Pressure-induced amorphization of YVO4:Eu3+ nanoboxes

2016

A structural transformation from the zircon-type structure to an amorphous phase has been found in YVO4:Eu3+ nanoboxes at high pressures above 12.7 GPa by means of x-ray diffraction measurements. However, the pair distribution function of the high-pressure phase shows that the local structure of the amorphous phase is similar to the scheelite-type YVO4. These results are confirmed both by Raman spectroscopy and Eu3+ photoluminescence which detect the phase transition to a scheelite-type structure at 10.1 and 9.1 GPa, respectively. The irreversibility of the phase transition is observed with the three techniques after a maximum pressure in the upstroke of around 20 GPa. The existence of two …

DiffractionPhase transitionMaterials sciencePhotoluminescenceAnalytical chemistryBioengineeringNanotechnology02 engineering and technologyNanocrystal010402 general chemistry01 natural sciencessymbols.namesakePhase (matter)General Materials ScienceElectrical and Electronic EngineeringMechanical EngineeringPair distribution functionGeneral Chemistry021001 nanoscience & nanotechnologyAmorphous phaseAmorphization0104 chemical sciencesHigh pressureNanocrystalMechanics of MaterialsFISICA APLICADAsymbols0210 nano-technologyRaman spectroscopy

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Evolution of the structural and optical properties from cobalt cordierite glass to glass-ceramic based on spinel crystalline phase materials

2007

Co 2+ -containing cordierite stoichiometric glasses have been prepared by melting colloidal gel precursors. After controlled thermal processing in the range of temperatures between 900 and 1300 C different polycrystalline, almost single phase materials displaying l-, a-, and b-cordierite crystalline forms were synthesized. In addition, spinel glass-ceramic materials were also prepared from the base glasses. All these materials were characterized by X-ray powder diffraction and infrared spectroscopy. Room temperature (RT) absorption and emission spectra of Co 2+ – cordierites and – spinel-glass material have allowed determining the local environment of the Co 2+ in the crystalline structure …

Materials scienceGlass-ceramicAbsorption spectroscopyCoordination numberSpinelInfrared spectroscopyMineralogyCordieriteengineering.materialCondensed Matter PhysicsElectronic Optical and Magnetic Materialslaw.inventionCrystallographylawvisual_artMaterials ChemistryCeramics and Compositesengineeringvisual_art.visual_art_mediumCeramicPowder diffractionJournal of Non-Crystalline Solids

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Broadband, site selective and time resolved photoluminescence spectroscopic studies of finely size-modulated Y2O3:Eu3+ phosphors synthesized by a com…

2014

Undoped and Eu3+-doped cubic yttria (Y2O3) nanophosphors of good crystallinity, with selective particle sizes ranging between 6 and 37 nm and showing narrow size distributions, have been synthesized by a complex-based precursor solution method. The systematic size tuning has been evidenced by transmission electron microscopy, X-ray diffraction, and Raman scattering measurements. Furthermore, size-modulated properties of Eu3+ ions have been correlated with the local structure of Eu3+ ion in different sized Y2O3:Eu3+ nanophosphors by means of steady-state and time-resolved site-selective laser spectroscopies. Time-resolved site-selective excitation measurements performed in the 7F0 ¿ 5D0 peak…

NanophosphorSize-modulated synthesisEu3+PhotoluminescenceMaterials scienceAnalytical chemistryStructureGeneral Physics and AstronomyPhosphorIonCrystalsymbols.namesakeCrystallinityNanocrystalFISICA APLICADAsymbolsGeneral Materials ScienceRaman spectroscopyRamanPhotoluminescenceRaman scatteringCurrent Applied Physics

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Effect of pressure on the luminescence properties of Nd3+ doped SrWO4 laser crystal

2008

Abstract The luminescence spectra of the 4 F 3/2 → 4 I 9/2 transition of Nd 3+ ions in a SrWO 4 crystal have been analyzed as a function of pressure at room temperature. Experiments have been performed in a diamond-anvil cell up to 13 GPa. At around 10 GPa some changes in the emission spectra have been observed which are attributed to a structural phase transition of the SrWO 4 matrix. These results are in good agreement with a previous paper, in which in a pure SrWO 4 matrix a scheelite to fergusonite phase transition is found around 10.5 GPa. Moreover, with increasing pressure, the decay curves from the 4 F 3/2 are nonexponential and faster indicating that the energy transfer processes …

Phase transitionChemistryMechanical EngineeringDopingMetals and AlloysAnalytical chemistryMineralogyFergusoniteIonCrystalchemistry.chemical_compoundMechanics of MaterialsScheeliteMaterials ChemistryEmission spectrumLuminescenceJournal of Alloys and Compounds

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CCDC 1826854: Experimental Crystal Structure Determination

2018

Related Article: Javier Conesa-Egea, Noemí Nogal, José Ignacio Martínez, Vanesa Fernández-Moreira, Ulises R. Rodríguez-Mendoza, Javier González-Platas, Carlos J. Gómez-García, Salomé Delgado, Félix Zamora, Pilar Amo-Ochoa|2018|Chemical Science|9|8000|doi:10.1039/C8SC03085E