Eu 3+ entrapped in alumina matrix obtained by hydrolytic and non-hydrolytic sol–gel routes

Abstract

The optimized conditions for the preparation of luminescent materials consisting of Eu 3+ entrapped in an alumina matrix are described. Eu 3+ ions in an alumina matrix have been prepared by sol–gel process using both non-hydrolytic (through the condensation of aluminum chloride with diisopropyl ether) and hydrolytic (by the reaction of aluminum chloride with aqueous NH 3) methodologies. Luminescence spectra, X-ray diffraction, surface areas, thermogravimetric properties and differential thermal properties have been measured. Through the non-hydrolytic sol–gel route we prepared amorphous, non-hydrated material with greater luminescence efficiencies and longer decay times, than for Eu 3+ in alumina prepared by other processes, even when heat treated at temperatures ⩽750 °C. The conventional hydrolytic sol–gel process produces materials where the Eu 3+ ions are imbedded in a crystalline alumina matrix containing water which increases quenching which reduces the luminescence efficiency of Eu 3+.