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 β-spodumene (Li2O·Al2O3·4SiO2, LAS4) 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 LAS4 precursor powders added with TiO2 has shown a major phase of β-spodumene and a minor phase of rutile. The fraction and size of pores decrease rapidly with sintering temperature increasing from 950 to 1350 °C. The pores were mainly interconnected at the sintering temperatures ⩽1050 °C; and become completely isolated at the sintering temperature of 1250 °C. The rutile precipitated in sintering of β-spodumene glass-ceramics prepared from LAS4 precursor powders with TiO2, appears in two different forms: the one with the size of about l.0 μm mainly segregates and agglomerates at the grain boundaries of β-spodumene; and the other consists of a few precipitates dispersed within the β-spodumene grains.