Effect of synthesis temperature on crystal structure and phonon modes of Ba[Zn1/3(Nb0.4Ta0.6)2/3]O3 ceramics

Abstract

Ba[Zn_1/3(Nb_0.4Ta_0.6)_2/3]O₃ (BZNT) solid solution ceramics were synthesized by conventional solid-state reaction method at 1450 °C, 1500 °C, and 1550 °C for 3 h. X-ray diffraction and Raman spectroscopy were employed to evaluate the effect of the synthesis temperature on the crystal structures and phonon modes of the investigated ceramics. XRD analysis indicates the formation of BZNT solid solutions and the distortion of the unit cell. From Raman data, it is verified that the BZNT ceramics have a higher symmetry of pseudocubic structure in comparison with the hexagonal BZT symmetry, which is caused by the unit cell distorted along the <111> plane as a result of the tilting of oxygen octahedra. Lorentzian lines were used to fit and, therefore, to determine the number of phonon modes for BZNT samples. The phase structures of the BZNT ceramics sintered at different temperatures were confirmed.