Effect of Polymer Cations on Photoluminescence Properties of Blue Emitting Alkaline-Earth Metals and Silicon Based Phosphors

摘要

Efficient blue emitting phosphors were prepared by depositing mixed hydroxides of Ca,Sr,Ba,Mg,Eu over spherical SiO2 particles from tetra-ethyl-orthosilicate(TEOS)pre-coated with polycations(polyethyleneimine:PEI)followed by calcination at 1200°C in a reducing atmosphere.The prepared phosphor showed intense blue emission,which can be ascribed to 4f7-4f6 5d interconfiguration transitions of Eu2+ ions.In contrast,the luminescence intensity of the phosphor was much decreased when prepared without polycations.It was suggested that negatively charged hydroxides are deposited on positively charged SiO2 surfaces pre-coated with polycations through electrostatic self-assembly interaction.The common formula of the prepared phosphors is AMgSi2O6:Eu2+(A=Ca,Sr,Ba or fraction of Ca and Sr),where alkaline-earth/Si=1,the each entire sample was prepared by treating with polycations and without polycations.