Wide range dielectric spectroscopy on perovskite dielectrics

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• 作者：Takashi Teranishi ; Takuya Hoshina ; Takaaki Tsurumi
• 关键词：Dielectric dispersion ; Relaxor ; Ferroelectrics ; Size effect ; Ferroelectric domain ; Barium titanate
• 刊名：Materials Science and Engineering: B
• 出版年：2009
• 出版时间：15 April 2009
• 年：2009
• 卷：161
• 期：1-3
• 页码：55-60
• 全文大小：914 K

文摘

Wide band dielectric spectra from the kilohertz to terahertz range were discussed for SrTiO₃ (ST) and BaTiO₃-based ceramics. The dielectric permittivity of BaTiO₃ (BT) is determined by the ionic polarization of the Slater mode as well as the dipole polarization of domain-wall vibrations in micro-sized domains. (Ba_x,Sr_1 − x)TiO₃ (BST) shows relatively high dielectric permittivity with a low dielectric loss up to GHz region, while Ba(Zr_xTi_1 − x)O₃ (BZT) shows a high permittivity with dielectric relaxation at MHz range. The dielectric dispersion in the BZT was due to the dipole fluctuation in polar nano-regions (PNR) in relaxors. The change of dielectric spectrum from BT to BZT was interpreted by the change from normal ferroelectrics to relaxors via ferroelectrics with diffuse phase transition (DPT-ferro.). Wide band dielectric spectra were also measured for BT ceramics with different grain and domain sizes to elucidate the size effect observed in BT ceramics. The low-frequency permittivity increased with decreasing grain size when the grain size was above 1 μm. It was found that the dipole polarization due to the domain-wall motion was enhanced with increasing domain density. We demonstrated wide band dielectric spectroscopy is a powerful tool to investigate the polarization mechanism of dielectric and ferroelectric materials.