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Influences of Ba/Ti Ratios on the Positive Temperature Coefficient of Resistivity Effect of Y‐Doped BaTiO 3 –(Bi 1/2 Na 1/2 )TiO 3 Ceramics
Author(s) -
Leng Senlin,
Li Guorong,
Zheng Liaoying,
Cheng Lihong,
Zeng Jiangtao
Publication year - 2011
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1551-2916.2011.04506.x
Subject(s) - electrical resistivity and conductivity , materials science , reducing atmosphere , sintering , tetragonal crystal system , analytical chemistry (journal) , temperature coefficient , doping , perovskite (structure) , ceramic , mineralogy , phase (matter) , atmospheric temperature range , composite material , metallurgy , chemistry , crystallography , physics , optoelectronics , chromatography , organic chemistry , meteorology , electrical engineering , engineering
Y‐doped (1− x mol%)BaTiO 3 – x mol%(Bi 1/2 Na 1/2 )TiO 3 (BBNT x ) lead‐free positive temperature coefficient of resistivity (PTCR) ceramics were prepared using a conventional solid sintering method. The Ba/Ti ratio was adjusted to obtain the optimized PTCR property. The results show that all 0.2 mol% Y‐doped BBNT15 samples with various Ba/Ti ratios have formed a single tetragonal perovskite phase by sintering in an N 2 atmosphere. The sample with 5 mol% (Bi 1/2 Na 1/2 )TiO 3 has only a minor PTCR effect (maximum resistivity [ρ max ]/minimum resistivity [ρ min ]) when sintered in N 2 . However, the PTCR effect is enhanced over 3.0 orders of magnitude when the (Bi 1/2 Na 1/2 )TiO 3 content is >8 mol%. The PTCR characteristics of the samples with Ti excess are superior to those with Ba excess. The optimum composition of 0.2 mol% Y‐doped BBNT15 with Ba/Ti=0.99, sintered at 1250°C for 3 h in an N 2 atmosphere, has a low room‐temperature resistivity (ρ 25 ) of ∼100 Ω·cm and a high PTCR effect of ∼4.8 orders of magnitude with T c around 190°C.