Morphology and microstructure in the sintering of β-spodumene precursor powders with TiO2 additive

The effect of TiO2 additions on the morphology and mechanism of sintering beta-spodumene (Li2O.Al2O3.4SiO(2), LAS(4)) glass-ceramics using organometallic precursor powders was investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron diffraction (ED). The crystalline phase formation in the calcination of LAS(4) precursor powders added with TiO2 has shown a major phase of beta-spodumene and a minor phase of rutile. The fraction and size of pores decrease rapidly with sintering temperature increasing from 950 to 1350 degreesC. The pores were mainly interconnected at the sintering temperatures less than or equal to 1050 degreesC; and become completely isolated at the sintering temperature of 1250 degreesC. The rutile precipitated in sintering of beta-spodumene glass-ceramics prepared from LAS(4) precursor powders with TiO2, appears in two different forms: the one with the size of about 1.0 mum mainly segregates and agglomerates at the grain boundaries of beta-spodumene; and the other consists of a few precipitates dispersed within the beta-spodumene grains. (C) 2002 Elsevier Science Ltd. All rights reserved.