Preparation and Diclectric Properties of Ferroelectric BaTiO_3 Thin Films by Sol-Gel Method

BaTiO_3薄膜在多层电容器、铁电存储器、热释电探测器和电光器件等方面有着广泛的应用。BaTiO_3薄膜的制备方法有溅射法、真空蒸发法、金属有机物分解法和溶胶-凝胶法等。近年来，人们采用活化反应蒸发法、脉冲激光分解法和溶胶-凝胶法制备了具有P-E电滞回线的BaTiO_3薄膜。而溶胶-凝胶法制备的BaTiO_3薄膜的介电常数-温度特性曲线在120 ℃附近没有居里峰。为了制备晶粒较大的BaTiO_3薄膜，采用了850 ℃的高温处理，方便了Pt板的使用。Pt基BaTiO_3薄膜的结晶度、表面形貌及电学性能 ...更多信息 Pt衬底上的BaTiO_3薄膜具有微粗的晶粒结构，晶粒尺寸约为50 nm。单层薄膜的微结构为不均匀的织构，晶粒尺寸约为450 nm。随着涂覆/加热过程的循环增加，小至约100 nm的细晶粒似乎从大的孤立晶粒的表面生长，并且最终，通过多次涂覆/加热过程制备的薄膜被强烈织构化，具有细晶粒。在Pt衬底上制备的BaTiO_3薄膜的P-E磁滞回线显示出良好的饱和磁滞回线。在室温下，薄膜的Pr为3.8，Ec为20 kV/cm。在Pt衬底上的薄膜在室温下表现出约830的ε r和0.04的tan δ。BaTiO_3薄膜在120 ℃附近没有居里峰，而在70 ℃附近出现宽居里峰，居里温度的差异可能是由于BaTiO_3的尺寸和微结构的影响。少

BaTiO_3 thin films have been intensively investigated for application to multilayr capacitors, ferroelectric memories, pyroelectric detectors and electrooptic devices. A number of techniques such as sputtering, vacuum evaporation, metalorganic decomposition and sol-gel methods have been used to prepare BaTiO_3 thin films. Recently, BaTiO_3 thin films that exhibit P-E hysteresis loops have been prepared by activated reactive evaporation, , pulsed laser decomposition and sol-gel methods. However, in the dielectric constant -temperaturecharacteristic curves of BaTiO_3 thim films prepared by sol-gel method, a curie peak was not observed at a temperature around 120ﾟC.In this work, BaTiO_3 thin films were prepared by sol-gel method. In order to prepare BaTiO_3 thin films with relatively large grains, the processing temperature as high as 850ﾟC was utilized, facilitating the use of Pt plate. Their crystallinity, surface morphology and electrical properties of BaTiO_3 thin films prepared on Pt … More substrate at 850ﾟC were examined.The BaTiO_3 thin films on Pt substrate exhibited a slightly coares grain microstructure with grain sizes of about 50nm. And, the microstructure of single-layr films showed inhomogeneous texture with large isolated grains of about 450nm. Increasing with the cycles of coating/heating process, fine grains as small as about 100nm seemed to grow from the surfaces of large isolated grains and, finally, thin films prepared by multiple coating/heating processes were strongly textured with fine grains. That is, the grain sizes of the top layr of the multilayr thin films were always much finer than those of the first coating.P-E hysteresis loops of BaTiO_3 thin films prepared on Pt indicated well-saturated hysteresis loops. And, these thin films prepared exhibited Pr of 3.8 and Ec of 20kV/cm at room temperature. The thin films on Pt substrate exhibited epsilonr of about 830 and tan delta of 0.04 at room temperature. And, inthese films, the curie peak was not seen at about 120ﾟC.However, broad curie peaks were observed at around 70ﾟC.The difference of the curie temperatures may be due to the effect of BaTiO_3 sizes and the microstructure. Less