The orientational growth of grains in doped BaTiO3PTCR materials by microwave sintering

Doped BaTiO3 (BTO) PTCR materials were sintered by microwave (MW) of 2.45 GHz at 1250 degreesC for 15 min. For comparison, identical samples (30 mm x 45 mm) were also sintered by conventional (CO) SiMo furnace at 1350 degreesC for 2 h. The experimental results show that the MW-sintered samples have a much greater axial linear shrinkage rate of 48% vs. the rate for the CO-sintered sample of 26%. This result has not yet been reported in other researcher works. Marked differences were also observed in the microstructure of the two samples by SEM, the grains in the CO-sintered sample showing on ecliptic spherical shape, whereas in MW-sintered samples the grains show an orientational strip-like microstructure. The XRD analysis indicates that the perovskite structure of MW-sintered BTO is tetragonal, whereas the CO-sintered sample is cubic. (C) 2002 Elsevier Science B.V. All rights reserved.