摘要
采用sol-gel法制备了钛酸锶钡(Ba_(1-x)Sr_xTiO_3)。用XRD、DSC、Raman等表征技术研究了Ba_(1-x)Sr_xTiO_3的晶体结构和相变行为。结果表明,随着锶含量的增加,晶胞体积逐渐减小,c/a趋近于1,相变温度降低,相变热减少,相变弥散性增强,且存在热滞现象。Raman光谱发生有趣变化,当x=0.30时,室温下发生结构相变,Ba_(1-x)Sr_xTiO_3以立方相为主要存在相,相变具有有序-无序特征。
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 a heat stagnation in phase transition. The Raman study suggests that the A(1)(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.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2003年第11期1005-1009,共5页
Acta Physico-Chimica Sinica
基金
国家自然科学基金(29971008)~~
