Piezoelectric properties in (K0.5Bi0.5)TiO 3-(Na0.5Bi0.5)TiO3-BaTiO 3 lead-free ceramics

• Published in: IEEE transactions on ultrasonics, ferroelectrics, and frequency control Vol. 54; no. 5; pp. 910 - 917
• Main Authors: Zhang, Shujun, Shrout, Thomas R., Nagata, Hajime, Hiruma, Yuji, Takenaka, Tadashi
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.05.2007; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anisotropic magnetoresistance; Bismuth; Ceramics; Dielectrics; Environmentally friendly manufacturing techniques; Piezoelectric devices; Piezoelectric materials; Powders; Solid state circuits; Temperature
• ISSN: 0885-3010; 1525-8955
• DOI: 10.1109/TUFFC.2007.336

Lead-free piezoelectric ceramics with compositions around the morphotropic phase boundary (MPB) x(Na 0.5 Bi 0.5 )TiO 3-y (K 0.5 Bi 0.5 )TiO 3 -zBaTiO 3 [x + y + z = 1; y:z = 2:1] were synthesized using conventional, solid-state processing. Dielectric maximum temperatures of 280degC and 262degC were found for tetragonal 0.79(Na 0.5 Bi 0.5 )TiO 3 -0.14(K 0.5 Bi 0.5 )TiO 3 -0.07BaTiO d3 (BNBK79) and MPB composition 0.88(Na 0.5 Bi 0.5 )TiO 3 -0.08(K 0.5 Bi 0.5 )TiO 3 -0.04BaTiO d3 (BNBK88), with depolarization temperatures of 224degC and 162degC, respectively. Piezoelectric coefficients d 33 were found to be 135 pC/N and 170 pC/N for BNBK79 and BNBK88, and the piezoelectric d 31 was determined to be -37 pC/N and -51 pC/N, demonstrating strong anisotropy. Coercive field values were found to be 37 kV/cm and 29 kV/cm for BNBK79 and BNBK88, respectively. The remanent polarization of BNBK88 (~40 muC/cm 2 ) was larger than that of BNBK79 (~29 muC/cm 2 ). The piezoelectric, electromechanical, and high-field strain behaviors also were studied as a function of temperature and discussed