Studies of dielectric characteristics of BaBi₂Nb₂O₉ ferroelectrics prepared by chemical precursor decomposition method

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• 关键词：Barium bismuth niobate ; CPD ; Ferroelectrics ; Low frequency dielectric dispersion ; Relaxor properties
• 刊名：Solid State Sciences
• 出版年：2007
• 出版时间：January 2007
• 年：2007
• 卷：9
• 期：1
• 页码：57-64
• 全文大小：487 K

文摘

BaBiNb₂O₉ (BBN) powders in the nanometer range were prepared by chemical precursor decomposition method (CPD). TG–DTA showed that precursor sample got freed from organic contaminants at 575 °C. XRD showed that a single phase with the layered perovskite structure of BBN was formed after calcining at 600 °C. No intermediate phase was found during heat treatment at and above 600 °C. The crystallite size (D) and the effective strain (η) were found to be 26 nm and 0.000867, respectively, while the particle size obtained from TEM was 28 ± 2 nm. SEM revealed that the average grain size after sintering at 900 °C for 4 h was 1.67 μm. A relative density of 93 % was obtained using a two-step sintering process at moderate pressure. Dielectric and ferroelectric properties were investigated in the temperature range 50–500 °C and frequencies from 1 kHz to 5 MHz. Strong dispersion of the complex relative dielectric constant was observed including typical relaxor features such as shift of permittivity maximum with frequency and broadening of the peak maximum. The high dielectric constant of 545 measured at 100 kHz and other properties of BBN ceramics were compared to that of BBN prepared by other conventional methods and found to be superior.