Preparation of reactive Sr-celsian powders by solid-state reaction and their sintering

In order to develop dense Sr-celsian (SrO·Al2O3·2SiO2) and hexacelsian ceramics, thermal reactions between kaolin and strontium carbonate were investigated. Sintering characteristics of powders and phase transformation from hexacelsian to celsian were clarified. Reactive amorphous powder could be prepared by calcination of the mixtures at 800 °C. Dense hexacelsian and celsian ceramics with a relative density of about 97% were successfully obtained by heat-treatment between 950 and 1200 °C. Relative dielectric constant and dielectric loss of hexacelsian ceramics was measured to be 5.3 and 0.5 × 10−4 (1 MHz), respectively, showing possibility for electrical applications.