Juan Carlos Rendon-Angeles
Centro de Investigacion y de Estudios Avanzados del IPN CINVESTAV-Saltillo, Mexico
Title: Insights of the hydrothermal synthesis of scheelite-structured powders in the SrMoO4-SrWO4 system: Structure and luminescence characterization
Biography
Biography: Juan Carlos Rendon-Angeles
Abstract
The present experimental work relates to a study of the hydrothermal powder processing of a functional luminescence compound. Strontium molybdate, strontium tungstate and their solid solutions were successfully prepared under hydrothermal conditions. The soft chemical method studied comprises the usage of SrSO4 (celestite) ore as the precursor of Sr. Particle crystallisation occurred rapidly because of a single step reaction, which was promoted using a highly concentrated alkaline media (5 M NaOH solution) at a temperature below 200ºC for 2 h under vigorous stirring at 130 rpm. In all the cases investigated, the particle crystallisation took place without the formation of secondary phases, while the ionic species representing impurities in the precursor mineral remained dissolved in the alkaline fluid. Differences in the morphology of the particles were observed when the W content varied from 25 mol% and 75 mol%. Additionally, the mechanism associated with the reaction and precipitation process investigated is discussed in detail, together with a crystalline structural characterization. Photoluminescence analyses indicate that blue and green emission responses and its intensity can be attenuated when incorporating W contents between 10 mol% and 60 mol%. Structural analysis conducted by Rietveld refinement and FT-Raman methods indicated that a localized distortion of the MO4 tetrahedral site of the scheelite structure is produced by the disordering of the Mo and W ions resulting in the blue and green emission attenuation. Hence, these present results indicate the intermediate SrMo1-XWXO4 particles have a potential to operate as a phosphorous-like light emitting material.