Zhang Shujun, Shrout Thomas R, Nagata Hajime, Hiruma Yuji, Takenaka Tadashi
Materials Research Institute, The Pennsylvania State University, University Park, PA 16802, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2007 May;54(5):910-7. doi: 10.1109/tuffc.2007.336.
Lead-free piezoelectric ceramics with compositions around the morphotropic phase boundary (MPB) x(Na0.5Bi0.5)TiO3-y(K0.5Bi0.5)TiO3-zBaTiO3 [x + y + z = 1; y:z = 2:1] were synthesized using conventional, solid-state processing. Dielectric maximum temperatures of 280 degrees C and 262 degrees C were found for tetragonal 0.79(Na0.5Bi0.5)TiO3-0.14(K0.5Bi0.5)TiO3-0.07BaTiO3 (BNBK79) and MPB composition 0.88(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3-0.04BaTiO3 (BNBK88), with depolarization temperatures of 224 degrees C and 162 degrees C, respectively. Piezoelectric coefficients d33 were found to be 135 pC/N and 170 pC/N for BNBK79 and BNBK88, and the piezoelectric d31 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 (approximately 40 microC/cm2) was larger than that of BNBK79 (approximately 29 microC/cm2). The piezoelectric, electromechanical, and high-field strain behaviors also were studied as a function of temperature and discussed.
采用传统的固态工艺合成了组分为x(Na0.5Bi0.5)TiO3-y(K0.5Bi0.5)TiO3-zBaTiO3 [x + y + z = 1; y:z = 2:1]且成分接近准同型相界(MPB)的无铅压电陶瓷。对于四方相的0.79(Na0.5Bi0.5)TiO3-0.14(K0.5Bi0.5)TiO3-0.07BaTiO3 (BNBK79)和MPB成分的0.88(Na0.5Bi0.5)TiO3-0.08(K0.5Bi0.5)TiO3-0.04BaTiO3 (BNBK88)，发现其介电最大值温度分别为280℃和262℃，去极化温度分别为224℃和162℃。发现BNBK79和BNBK88的压电系数d33分别为135 pC/N和170 pC/N，且压电d31分别为-37 pC/N和-51 pC/N，显示出很强的各向异性。发现BNBK79和BNBK88的矫顽场值分别为37 kV/cm和29 kV/cm。BNBK88的剩余极化(约40 μC/cm2)大于BNBK79的剩余极化(约29 μC/cm2)。还研究了压电、机电和高场应变行为随温度的变化并进行了讨论。
