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Microstructure-Properties Relationship in Barium Titanate Ceramics

In this research, the effects of two kinds of additives in Barium Titanate ceramics were studied, in order to related the microstructure to electrical properties of the system. In the first series, the effects of Cerium (as a dopant) and in the second series the effects of Cerium along with lead on the electrical properties (with emphasis on the PTCR behavior) were evaluated. The amount of Ce was changed from 0.1% to 0.5% mole and the amount of Pb was 30% which was considered to be substituted to Ba sites. The first series were sintered from 1100 °C to 1350 °C and the second ones from 1100 °C to 1300 °C. After polishing and coating, the electrical properties were measured and analyzed. The results showed that Ce doping lowers the resistance of the systems (in both cases, without and with Pb) up to 0.3 % mole and increased after that. The addition of Pb had increased the Tc of the system. The optimal sintering temperatures were about 1350 °C and 1200 °C in the first and second series respectively. In the first series, the Tc was about 125 °C and in the second series 180-200 °C. X-ray diffractometry showed that in the first series, the dominant phase was pure Barium Titanate and in the second series Barium Lead Titanate.