EFFECT OF BTS CONTENT ON MICROSTRUCTURE AND DIELECTRIC PROPERTIES OF 0-3 BTS CERAMIC/ACSA CEMENT COMPOSITES

The effect of BaTi0.91Sn0.09O3 (BTS) ceramic content (between 30 to 70 % volume) on microstructure and dielectric properties of BTS/Alite calcium sulfoaluminate cement composites was studied. The BTS ceramic was fabricated by the conventional solid-state reaction method. The powders and ceramics were calcined and sintered at the temperatures of 1,200°C for 2 h and 1,400°C for 4 h, respectively. The 0-3 dielectric composite consisted of BTS as the dielectric phase and ACSA as the matrix phase and were produced by the pressing and curing technique. The SEM micrographs illustrated a typical interfacial transition zone (ITZ) between the BTS ceramics and the ACSA cement matrix and there was a slight increase of pores when BTS content increased. Effective binding was observed at 30, 40, and 50 volume % BTS while increased cracking of BTS ceramics was observed at the ITZ boundary as the BTS ceramic content increased to 60 and 70 %. The dielectric constant (εr) at 1 kHz increased with increased BTS ceramic content, up to 50 volume %, and then decreased due to the presence of pores and cracks in the BTS ceramic phase. The dielectric loss (tan δr) at 1 kHz decreased as the ceramic content increased, while the dielectric constant (εr) followed the predictions of the cubic model. It appeared that the ceramics were randomly distributed in the composite. The values of εr and tan δr decreased with increased frequencies, measured in the range of 1-1,000 kHz.