Acta Phys. -Chim. Sin. ›› 2003, Vol. 19 ›› Issue (11): 1005-1009.doi: 10.3866/PKU.WHXB20031104

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Preparation and Structure Phase Transition of Ba1-xSrxTiO3 by Sol-gel Technique

Guo Hui-Fen;Zhang Zhong-Suo;Liu Bing;Zhang Xing-Tang;Li Yun-Cai;Huang Ya-Bin;Du Zu-Liang   

  1. Key Laboratory of Special Functional Materials,Henan University,Kaifeng  475001
  • Received:2003-03-26 Revised:2003-06-19 Published:2003-11-15
  • Contact: Du Zu-Liang E-mail:zld@henu.edu.cn

Abstract: A series of Ba1-xSrxTiO3 were prepared by sol-gel method. The crystal structure and phase transition of Ba1-xSrxTiO3 were studied by XRD、DSC and Raman spectra. The results suggest that the Sr dopant can decrease the cell volume effectively. With the increasing of the Sr dopant content, a axis and c axis become shorter and shorter and the value of c axis decreases more quickly than that of a axis. The axial ratio c/a approaches 1 gradually according to the increase of the Sr dopant content. At x=0.3 and room temperature, the cell aberrance occurs and Ba1-xSrxTiO3 exits mainly in cubic paraelectric phase. With the increase of Sr dopant, the potential well becomes shallow which results that the phase transition temperature becomes low and heat of phase transition becomes small and the phase transition becomes diffusive. There exists heat stagnation in phase transition. The Raman study suggests that the A1(TO2) optical phonon peak at 515 cm-1 splits into two peaks gradually while their intensity vary reversely. The other lower frequency phonon modes shift to the lower frequency while the higher frequency phonon modes shift to the higher frequency while each optical phonon peak becomes lower and broader. At room temperature, the transition of Ba1-xSrxTiO3 occurs from a ferroelectric tetragonal to a paraelectric cubic phase at x=0.30,which the Raman spectra support the order-disorder ferroelectric phase transformation.

Key words: Barium stront ium titanate, Sol-gel, Lattice constant, Structural phase transition