Chromium incorporation into TiO 2 up to 3 GPa at 1300 °C and 900 °C has been studied by XRD as well as TEM. A CaCl 2 type TiO 2 polymorph has been observed in the quenched samples from high pressure. Two different mechanisms of solubility occur in the recovered samples. Chromium replaces titanium on…
Silicon incorporation in TiO 2 phases at increasing pressures until 20 GPa at 1300 °C has been studied by XRD and TEM. Rutile is the stable Si-doped TiO 2 phase until at least 7 GPa, transforming into α-PbO 2 structured TiO2 between 7 and 10 GPa. The further transformation to the TiO 2 polymorph with…
The synthesis and structure resolution of RbLaF4 are described. RbLaF4 is synthesized by solid-state reaction between RbF and LaF3 at 425 degrees C under a nonoxidizing atmosphere. Its crystal structure has been resolved by combining neutron and synchrotron powder diffraction data refinements (Pnma, a = 6.46281(2) angstrom, b = 3.86498(1) angstrom, c = 16.176:29(4) angstrom,…
En este proyecto se estudiarán las modificaciones que tienen lugar tanto en la absor-ción como en la emisión ópticas de nanomateriales de diverso tipo (nanopartículas dopadas con tierras raras, nanopartículas semiconductoras, nanopartículas metálicas, films de coloran-tes orgánicos de grosor nanométrico) por el hecho de encontrarse éstos formando parte de una estructura fotónica en la que…
El proyecto AL-NANOFUNC ha sido diseñado para poner en marcha en el Instituto de Ciencia de los Materiales de Sevilla (ICMS, CSIC-Univ.Sevilla, España) un laboratorio avanzado para el Nano-análisis de nuevos materiales funcionales. Las técnicas de Nanoscopía avanzada, basadas en equipos de microscopía electrónica de última generación, se dedicarán a la investigación de vanguardia en…
The angular properties of light emitted from rare-earth based nanophosphors embedded in optical resonators built in one-dimensional photonic crystal coatings are herein investigated. Strong directional dependence of the photoluminescence spectra is found. Abrupt angular variations of the enhancement caused by the photonic structure and the extraction power are observed, in good agreement with calculated polar…
Monodisperse YF3:Tm3+/Yb3+ nanocrystals have been synthesized to explore the visible up-converting properties under near infrared (975 nm) excitation. It has been found that the nanoparticles exhibit intense red up-converted emissions, in addition to the characteristic UV and blue Tm3+-bands. It is demonstrated that, by carefully selecting Tm3+ and Yb3+ contents, the relative intensity of the…
A simple and single-step method for the production of Ln-doped YVO 4 nanocrystals and their simultaneous encapsulation in a silica network based on the pyrolysis of liquid aerosols at 800 °C is reported. The procedure is illustrated for Yb,Er:YVO4-silica nanocomposites consisting of spherical particles, which present up-converted green luminescence after IR excitation whose efficiency increased…
