Effect of A-site off-stoichiometry on the microstructural, structural, and electromechanical properties of lead-free tetragonal 0.80Na0.5Bi0.5TiO3–0.20BaTiO3 (NBT–20BT) piezoceramic

• Published in: Journal of materials science. Materials in electronics Vol. 32; no. 9; pp. 12578 - 12593
• Main Authors: Mishra, Anupam, Abebe, Getaw, Jafo, Gudeta, Das Adhikary, Gobinda, De, Arnab
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.05.2021; Springer Nature B.V
• Subjects: Bismuth titanate; Characterization and Evaluation of Materials; Chemistry and Materials Science; Composition; Distortion; Electric fields; Ferroelectricity; Grain size; Heterogeneity; Lead free; Materials Science; Microscopy; Optical and Electronic Materials; Piezoelectric ceramics; Polyvinyl alcohol; Solid solutions; Stoichiometry; Tetragonal lattice; Ultrasonic transducers
• ISSN: 0957-4522; 1573-482X
• DOI: 10.1007/s10854-021-05895-6

A-site off-stoichiometry has been an efficient method to enhance the electromechanical properties of lead-free Na 0.5 Bi 0.5 TiO 3 (NBT)-based piezoceramics. In this work, we have reported the effect of Na/Bi off-stoichiometry on the microstructural, structural, and electromechanical properties of the tetragonal 0.80Na 0.5 Bi 0.5 TiO 3 –0.20BaTiO 3 (NBT–20BT) ceramic. The maximum piezoresponse ~ 115 pC/N is obtained for 4 mol% Na-deficient (20BT–Na46) and 2 mol% Bi-excess (20BT–Bi52) compositions. It is a 25% increment over the piezoresponse of the stoichiometric composition (20BT–Na50 ~ 90 pC/N). The enhancement in piezoresponse has been attributed to an optimized presence of polar-structural heterogeneity/disorder in the poled ceramic matrix and an optimized distortion of the long-range tetragonal ferroelectric phase. It is established that A-site off-stoichiometry is influencing the polar-structural heterogeneity/disorder and tetragonal lattice distortion via the grain size.