Hydrothermally assisted complex polymerization method for barium strontium titanate powder synthesis
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ORIGINAL PAPER
Hydrothermally assisted complex polymerization method for barium strontium titanate powder synthesis ´ irkovic´ • Katarina Vojisavljevic´ • Maja Sˇc´epanovic´ Jovana C Aleksander Recˇnik • Goran Brankovic´ • Zorica Brankovic´ • Tatjana Srec´kovic´
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Received: 30 June 2012 / Accepted: 31 October 2012 / Published online: 18 November 2012 Ó Springer Science+Business Media New York 2012
Abstract Barium strontium titanate was obtained by hydrothermal treatment of barium strontium titanate citric precursor solution, previously prepared by complex polymerization method. The thermally induced phase evolution was followed at various temperatures up to 800 °C using thermogravimetric and differential thermal analysis, X-ray diffraction analysis, and Raman spectroscopy. Microstructural characterization of barium strontium titanate powders was performed by scanning and transmission electron microscopy. The proposed synthesis route has been proven as a better and faster method for barium strontium titanate powder preparation as compared to the conventional complex polymerization route. The method was found efficient for production of low agglomerated, fine, nanosized barium strontium titanate powder with well defined stoichiometry, and sub-micron particle size. The results of structural and microstructural characterization showed the complete crystallization of carbonate-free barium strontium titanate powder at 700 °C with an average size of crystallites below 50 nm.
J. C´irkovic´ (&) K. Vojisavljevic´ G. Brankovic´ Z. Brankovic´ T. Srec´kovic´ Institute for Multidisciplinary Research, University of Belgrade, Kneza Visˇeslava 1, 11030 Belgrade, Serbia e-mail: [email protected] M. Sˇc´epanovic´ Center for Solid State Physics and New Materials, Institute of Physics, University of Belgrade, Prigrevica 118, 11080 Belgrade, Serbia A. Recˇnik Department for Nanostructured Materials, Jozˇef Stefan Insitute, Jamova cesta 39, 1000 Ljubljana, Slovenia
Keywords Barium strontium titanate Sol–gel processes Hydrothermal synthesis X-ray diffraction Raman spectroscopy Transmission electron microscopy
1 Introduction Barium strontium titanate, BaxSr1-xTiO3 (BST) has been used in the preparation of dynamic random access memories (DRAM), piezoelectric and pyroelectric sensors, microwave phase shifters, infrared detectors and tunable devices, due to their excellent ferroelectric, dielectric, piezoelectric, and pyroelectric properties [1–5]. Curie temperature could be easily adjusted by changing the Ba to Sr ratio, and varies between 120 °C for pure BaTiO3 and -163 °C for pure SrTiO3. At room temperature BaxSr1-xTiO3 is ferroelectric when the Ba content x is in the range of 0.7–1, and has a maximum dielectric constant around x = 0.8 [6, 7]. The mentioned characteristics of BST powders strongly depend on their synthesis. To achieve the desired properties and practical application, BST powder needs to be free of intermediate phases, with a defined stoichiometry and homogenous microstructure. The commonly used techniqu
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