Simple oxalate precursor route for the preparation of barium-strontium titanate : Ba1-xSrxTiO3 powders

• Published in: Materials characterization Vol. 54; no. 1; pp. 63 - 74
• Main Authors: KHOLLAM, Y. B, DESHPANDE, S. B, POTDAR, H. S, BHORASKAR, S. V, SAINKAR, S. R, DATE, S. K
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Science 2005
• Subjects: Cross-disciplinary physics: materials science; rheology; Exact sciences and technology; Materials science; Phase diagrams and microstructures developed by solidification and solid-solid phase transformations; Physics; Solidification; Barium-strontium titanate; Barium-strontium titanyl oxalate; Oxalates; Permittivity; XRF
• ISSN: 1044-5803; 1873-4189
• DOI: 10.1016/j.matchar.2004.11.002

A simple one--step cation--exchange reaction between the stoichiometric solutions of ammonium titanyl oxalate (ATO) and barium hydroxide+strontium nitrate at room temperature (RT) is investigated successfully for the quantitative precipitation of barium--strontium titanyl oxalate (BSTO): Ba1--xSrxTiO(C2O4)2*4H2O (x=0*25) precursor powders with nearly theoretical yield ( > =99%). The pyrolysis of BSTO at 730 deg C/4 h in air produced barium--strontium titanate (Ba1--xSrxTiO3; BST) powders. The characterization studies on BSTO and BST powders by using various physico--chemical techniques: micro-- and chemical analysis, differential thermal analysis (DTA)/thermo--gravimetric analysis (TGA), XRD, FTIR, X--ray fluorescence (XRF) and scanning electron microscopy (SEM) revealed that the powders formed are cubic, highly pure, stoichiometric and sub--micron--sized with nearly uniform size and shape distribution. The ceramic compacts obtained by sintering the BST pellets at 1300 deg C/4 h showed density ~95%, dielectric constant *?(Tc)~9500, tan delta~0*15% and TC~32 deg C.