Synthesis of star shaped Ba 1− xSr xTiO 3 (BST) powders

Abstract

Uniform star shaped strontium substituted barium titanyl oxalate Ba 1− x Sr x TiO(C 2O 4) 2 (BSTO)/strontium substituted barium titanate, Ba 1− x Sr x TiO 3 (BST) powders were prepared via a simple chemical co-precipitation route with x = 0.15, 0.20, and 0.25. The process involved an addition of 0.1 M solution of titanium tetrabutoxide (BTM) in isopropanol (IPA) to 0.1 M oxalic acid in IPA containing 0.2 M of H 2O to produce titanyl oxalate precipitate which was further reacted with 0.1 M solution of ammonium oxalate to obtain 0.1 M clear homogeneous solution of ammonium titanyl oxalate (ATO) with pH 4.25 containing titanium in the form of soluble anionic oxalate species [TiO(C 2O 4) 2 2−]. Stoichiometric quantities of barium hydroxide and strontium nitrate were dissolved in distilled water and its pH was adjusted nearly equal to that of ATO (∼4.15) by drop wise addition of dilute HNO 3 solution 1:10 (v/v). The addition of this mixed cation precursor solution to ATO solution resulted in precipitation of strontium substituted barium titanyl oxalate (BSTO) having star shaped morphology. The calcination of BSTO precursors at 730 °C for 4 h in air produced cubic BST powders ( a 0 ∼4.001, 3.996 and 3.991 Å for x = 0.15, 0.20, 0.25, respectively) having star shaped morphology. SEM, XRD and FTIR techniques were used to characterize the BSTO/BST powders.