Structure and properties of Ba(Zr0.2Ti0.8)O3 ceramics prepared by spark plasma sintering
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Ba(Zr0.2Ti0.8)O3 (BZT) ceramics are prepared from spray-dried powder by spark plasma sintering (SPS) and by normal sintering. By the application of SPS, ceramics with >96% relative densities could be obtained by sintering at 1,100 °C for 5 min in air atmosphere. The pellet as sintered by SPS at 1,100 °C was black and conductive. Although SPS was carried out in air atmosphere, the samples were deoxidized by heating the carbon die. By post-annealing at 1,000 °C for 12 h in air, the pellet was oxidized and became white and insulating. Grain growth was suppressed in the ceramics prepared by SPS, and the average grain size was 0.52 μm. The starting powder contained 1.90% carbon, mainly as binder, and the SPS-prepared ceramics and ordinary prepared ceramics contained 0.15 and 0.024% carbon, respectively. The BZT ceramics obtained by SPS and the subsequent annealing at 1,000 °C for 12 h exhibited a mild temperature dependence of their dielectric constant. The field-induced displacement of the BZT ceramics was less hysteretic and smaller than that of the ceramics sintered by the conventional method.
KeywordsBaTiO3 Spark Plasma Sinter Barium Titanate Conventional Sinter Electromechanical Property
I would like to thank Mr. Masakazu Kawahara of SPS Syntex Inc., for the spark plasma sintering of the BZT powders.