Spark Plasma Sintering of Tungsten Bronze Sr2−xCaxNaNb5O15 (x= 0.1) Piezoelectric Ceramics: II, Electrical Properties

• Published in: Journal of the American Ceramic Society 2002-11, Vol.85 (11), p.2731-2737
• Main Authors: Xie, Rong-Jun, Akimune, Yoshio, Wang, Rui-Ping, Hirosaki, Naoto
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Dielectric, piezoelectric, ferroelectric and antiferroelectric materials; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Niobates, titanates, tantalates, pzt ceramics, etc; Physics; piezoelectric materials/properties; spark plasma sintering; tungsten/tungsten compounds
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.2002.tb00521.x

Sr2−xCaxNaNb5O15 (SCNN, x= 0.1) piezoelectric ceramics with tetragonal tungsten bonze structure were successfully produced by spark plasma sintering. Part I of this study presented the sintering of these highly dense ceramics. The current work investigates their electrical (dielectric, ferroelectric, and piezoelectric) properties and relates them to the sintering parameters (temperature, heating rate, and soaking time) and crystallographic orientation. The results show that the electrical properties of SCNN are enhanced with increasing heating rate and soaking time. Dielectric study reveals a less pronounced diffuse phase transition of SCNN. Anisotropic electrical properties were observed as a result of the preferred crystallographic orientation in the sintered ceramics. The samples sintered at 1200°C for 30 min exhibited the highest electrical properties, and showed the following piezoelectric properties when poled across the direction perpendicular to the pressing direction: electromechanical planar and thickness coupling coefficients of kp= 9.5% and kt= 39.6%, and piezoelectric constant of d33= 121 pC/N (∼45% of the single‐crystal value).