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Effects of A-Site (NaCe) Substitution with Na-Deficiency on Structures and Properties of CaBi 4 Ti 4 O 15 -Based High-Curie-Temperature Ceramics

2001; Institute of Physics; Volume: 40; Issue: 11R Linguagem: Inglês

10.1143/jjap.40.6501

1347-4065

Haixue Yan, Chengen Li, Jiaguang Zhou, Weimin Zhu, Lianxin He, Yuxin Song, Youhua Yu,

Microwave Dielectric Ceramics Synthesis

Three kinds of bismuth-layer-structured ferroelectric (BLSF) ceramics, CaBi 4 Ti 4 O 15 (CBT), Ca 0.8 (CeNa) 0.1 Bi 4 Ti 4 O 15 (CNBT), and Na-deficient Ca 0.8 (Ce 0.1 Na 0.05 \Box 0.05 )Bi 4 Ti 4 O 15 [CN\BoxBT] (where \Box represents vacancies) were prepared by a conventional ceramic technique. X-ray powder diffraction showed that their crystal structures are a single phase of BLSF with m =4. Sintering characteristics of the three ceramics were also discussed. Scanning electron microscope (SEM) micrographs of CN\BoxBT showed that the grain is platelike. The A-site (NaCe) substitution can improve the piezoelectric constant d 33 and high-temperature resistivity with decreasing Curie temperature. The modification by A-site (NaCe) substitution with Na-deficiency is more pronounced than CNBT, which not only leads to a very high piezoelectric constant d 33 and high-temperature resistivity but also increases the Curie temperature. The reason for the high T c ( T c =866°C) of CN\BoxBT is considered to be internal stress. As a result, Na-deficient CN\BoxBT ceramic is found to be an excellent high-temperature piezoelectric material.