Advanced Techniques for Preparation of Strontium Aluminate Phases

Abstract

The solid state synthesis described in Chapter 4.3 is the traditional way for the synthesis of strontium aluminate phase. Small amounts of fluxing agents (Fig.1), such as B 2 O 3 (H 3 BO 3) or LiF can be used [749,810]. Figure 1. Flow chart of the preparation of REE doped SrAl 2 O 4 phosphor powders [749]. There are also advanced techniques of the synthesis of strontium aluminate phases including the sol-gel process, the precipitation from solution, the pyrolysis and combustion techniques, the microwave synthesis, the mechano-chemical route, etc. It must be pointed, that the techniques mentioned in this chapter are the sophisticated synthesis routes which are tailored mainly for the processing of nano-scale powders, doped with rare earth elements (REE ions such as Ce 4+ , Eu 2+ , Dy 3+ …), in order to prepare the precursors for strontium aluminate based phosphors for long-persistent luminescence materials, electronic and structural applications (Chapter 10.1). Therefore, the suitability of the techniques mentioned above for the synthesis of strontium aluminate clinker is limited by their complexity, time-consuming preparation process, labor productivity and by the cost of applied chemicals. The Sol-gel process is a method based on the turn of the " free dispersion system " with particles of colloidal size (sol) into " bound dispersion system " (gel) with the particles cross-linked into the three-dimensional network. In principle there are two ways of the formation of gel: