Correlation of sol–gel processing parameters with microstructure and properties of a ceramic product

Abstract

A very high purity MgAl 2O 4 spinel precursor can be prepared via a low temperature process called “Oxide One Pot Synthesis (OOPS)”. Sol–gel processing of such precursors offers the opportunity to prepare spinels with controlled microstructures, which is key to optimizing their properties for application as humidity sensors. Sol–gel processing of a double alkoxide precursor was carried out in buffer solutions in the pH range 8–12, to investigate the effect on the physical properties of the calcined ceramic products. The structure and morphology of the latter were characterized using FTIR, XRD, SEM and BET surface area measurements. Sol–gel processing results in a calcined product with a narrow pore size distribution, which contains a spinel phase of high crystallinity. At higher pH values, increasing amounts of an α-Al 2O 3 phase are formed. At all pH values, the calcined product exhibits high water adsorption, up to 0.312 g H 2O/g sample.