中文摘要：

研究并比较了两种不同（Ba0.5，Sr0.5）TiO3（BSTO）薄膜介电．温度特性．采用脉冲激光沉积技术在Pt／Ti／SiO2／Si（100）衬底上制备BSTO薄膜，发现制备条件的不同，可以得到介电性质完全不同的BSTO薄膜．在550℃和氮气氛下制备的BSTO薄膜在常温下具有很高的介电常数，在10kHz下．超过2500，并在200K温度以上介电常数基本不变．它的一些电学性质不同于在正常条件（650℃和氧气氛下）制得的BSTO薄膜，而类似于目前广泛报道的巨介电常数材料如CaCu3Ti4O12两种薄膜介电性质测试结果表明：氧气氛下制备的BSTO薄膜呈现铁电．顺电相变，符合居里．外斯定律；低温氮气氛下制备的BSTO薄膜，介电弛豫时间和温度的关系符合德拜模型．是热激发弛豫．文中给出了产生这种介电特性的初步解释。

英文摘要：

A high dielectric constant of 2500 near room temperature was observed in （ Bao0.5 Sr0.5 ） TiO3 （BSTO） film prepared by pulsed-laser deposition （PLD） on Pt/Ti/SiO2/Si （100） substrate at 550℃ in N2 atmosphere. The dielectric constant is weakly temperature dependent above 200 K. The dielectric behavior of this film is different from the BSTO film deposited in the O2 atmosphere, but very similar to that reported for the so-called ＂colossal＂ dielectric constant materials, such as CaCu3Ti4O12. The film prepared in O2 atmosphere at 650℃ shows normal ferroelectric phase transition, which are fitted with Curie-Weiss law. However, for the film prepared in N2 atmosphere at 550℃, the temperature dependence of dielectric relaxation can be characterized by a thermally excited relaxation process. Such anomalous dielectric response of the BST films is ascribed to the formation of the Schottky barrier between the metallic electrode and the film surface.