Crystal structure and electromechanical coupling properties of Na0.5Bi2.5Ta2O9 dense ceramics

The crystal structure of sodium bismuth tantalate, Na_0.5Bi_2.5Ta₂O₉, was analyzed by the powder X-ray-diffraction Rietveld method. The distribution of Na atoms was found to be ordered in the A site of the pseudo-perovskite (ATa₂O₇)^2- blocks. The piezoelectric properties were effectively examined using dense bulk ceramics containing manganese oxide as the dopant. The electromechanical coupling coefficients (k_ij) and the electrical quality factors (Q_m) are k_p=10%, k₃₁=8.3%, k_t=19.7%, and Q_m=3000. Received: 1 July 2002 / Accepted: 3 July 2002 / Published online: 10 September 2002 RID="*" ID="*"Corresponding author. Fax: +81-743-726069, E-mail: hiro-t@ms.aist-nara.ac.jp