Effect of calcination temperature on crystallite size and tetragonality of thebarium titanate nano powders synthesized by chemical co-precipitation

With the rapid developing of electronic industries, high purity nanopowders of barium titanate(BaTiO۳) with suitable size distribution and morphology are required greatly for manufacturingelectronic devices. Thus, it is meaningful work to investigate new routes at low temperature toprepare ultra-fine particles of BaTiO۳. In this way, Chemical co precipitation has been applied tosynthesize high purity barium titanate powders. A barium titanate was prepared from TiCl۴, BaCl۲.۲H۲O and NaOH, then calcined for ۴ hours at ۶۰۰, ۷۰۰ and ۸۰۰˚C. Phase transformation andcrystallite size of the as synthesized powder and calcined powders were investigated as a functionof the calcination temperature by X-ray diffraction (XRD) methods. In addition particlemorphology and size were studied by field emission scanning electron microscopy (FESEM). Withincreasing calcination temperature pure BaTiO۳ obtained and transformed from the cubic to theferroelectric tetragonal phase. The tetragonality (c/a) increases with increasing calcinationtemperature and increasing crystallite size, respectively. Higher temperature clearly favouredparticle growth and formation of large and hard agglomerates. The crystallite size of the tetragonalphase increased from ۴۶-۷۵ nm at ۷۰۰˚C to ۵۰-۳۵۰ nm at ۸۰۰˚C according to FESEM images.This means increasing temperature has been lead to less homogeneous particle distribution

Keywords:

Barium titanate , co-precipitation , calcination , nano powder , tetragonality