Effects of sintering and paste-baking conditions on PTCR characteristic of (Ba,Sr)TiO{sub}3 vaccum-sintered compact added with TiO{sub}2(Ti) powder

摘要

The effects of sintering temperature (T{sub}s; l573-l748K) and time (t{sub}s; 0.6-14.4ks) and paste-baking-temperature or heating temperature (T{sub}h or T{sub}b; 673-l273K; t{sub}b is 0.3ks) on PTCR characteristic were investigated for (Ba,Sr)TiO{sub}3 vacuum-sintered compact added with 3.9mass% TiO{sub}2(Ti) powder of 12.5mass% TiO{sub}2. The results obtained were as follows; (1)PTCR characteristic developed at all T{sub}s(t{sub}s=3.6ks, T{sub}b=853K). The electrical resistivity at room temperature (ρ{sub}(rt)) showed a minimum value of 1.8 x 10{sup}2Ω cm and theρ{sub}(max)/ρ(rt) showed a maximum value of about 10{sup}6 at 1723K. (2)For all t{sub}s(T{sub}s=l623K, T{sub}b=853K), PTCR characteristic developed. Theρ{sub}(rt)showed a minimum value of 2.6× 10{sup}3Ω.cm at 7.2ks. (3) At T{sub}b above 823K (T{sub}s=l623K, t{sub}s=3.6ks), PTCR characteristic developed. The Pr showed a minimum value of 1.0×10{sup}3Ω.cm. (4)Theρ-T curve of (Ba,Sr)TiO3+TiO2(Ti) vacuum-sintered compact was affected more largely by T{sub}s, t{sub}s and Tb than that of (Ba,Sr)TiO{sub}3 air-sintered compact. This was considered to be mainly due to the porous and fine grained microstructure in the former compact.