Effect of Annealing Temperatures on Formation of Na0.5Bi0.5TiO3 and (Na0.5Bi0.5)0.96Ba0.04TiO3 Ceramics Prepared via Sol Gel Method

Abstract

The effect of annealing temperatures on the formation of pure perovskite Na0.5Bi0.5TiO3 (NBT) based ceramics prepared by sol gel method has been investigated. The NBT sol was prepared using NaCH3COO, C6H9BiO6 and Ti(C4H9)4 with 2-methoxyethanol and glacial acetic acid were used as solvents. The BaTiO3 sol was synthesized using C4H6BaO4 and Ti(C4H9)4 with acetic acid and ethanolamine were used as solvents. The (Na0.5Bi0.5)0.96Ba0.04TiO3 (NBBT) sol was prepared by mixing appropriate amount of NBT and BaTiO3 sols. Then NBT and NBBT sols were dried at 200oC for 24 h, ground and subsequently annealed at temperatures ranging from 440oC – 640oC for 5 min. Formation of NBT and NBBT ceramics was examined using XRD technique. X-ray diffractograms reveal that the NBT ceramic with rhombohedral structure starts to form at 540oC and complete crystallization is achieved at 620oC. Addition of 4vol% of BaTiO3 sols drastically reduces the crystallization temperature of NBBT ceramic to 460oC and a pure single phase ceramic is achieved at 520oC. Despite retaining the same rhombohedral structure, the NBBT exhibits lattice parameters expansion indicating a successful Ba substitution which is also confirms by the absence of BaTiO3 peaks in the diffractograms. Both ceramics exhibit great thermal stability with additional increment in annealing temperatures.