Effect of Nd modification on electrical properties of mixed-layer Aurivillius phase Bi_4Ti_3O_(12)-SrBi_4Ti_4O_(15)

摘要

The effect of Nd modification on ferro-, piezo-, and dielectric properties of intergrowth Bi_4Ti_3O_(12)-SrBi_4Ti_4O_(15) ceramics was investigated. X-ray diffraction and Raman scattering were used to identify the crystal phase and to distinguish the doping sites. With increasing Nd content up to 0.50, both remanent polarization (2P_r) and piezoelectric coefficient (d_(33)) were found to increase and reach the maximum value of 33.2 μC/cm~2 and 14 pC/N, respectively, which gained an enlargement over 1.7 times in 2P_r and a desirable 75% increment in d_(33) value. However, further Nd modification starts to deteriorate the ferro- and piezoelectric behavior. Impedance spectroscopy shows the activation energy of conductivity increased with increasing Nd content, which can be regarded as direct proof of the restraint of oxygen vacancies. The thermal variations of dielectric permittivity and loss tan δ with Nd content show the characteristic of diffuse phase transformation while the convincible defect-related relaxation phenomenon was not found. Interestingly, in contrast to La modification, Nd modification does not induce the relaxor behavior even at very high doping content.