纳米晶钛酸铅表面态对介电性能的影响

将醋酸铅、钛酸四丁酯和硬脂酸在熔融状态下混合均匀后置于冷水浴中，使其凝固成凝胶，经不同温度焙烧，制成纳米晶PbTiO3.用X射线衍射光谱、红外光谱对产物进行表征.采用X射线光电子能谱和表面光电压谱对纳米晶PbTiO3表面状态分析,发现材料表面的不完整性主要是由氧空位造成.暴露在粒子表面的主要是金属离子.随着晶粒尺寸的减小，材料表面氧空位缺陷浓度增加，表面光伏效应增强，谱带变宽.纳米晶PbTiO3材料的表面状态对其极化性质有着重要的影响，使其静态介电常数远大于常规材料的静态介电常数.

Effects of Surface State of Nanocrystal PbTiO3 on Their Dielectric Properties

Nanocrystalline PbTiO3 powder was obtained by melting appropriate amount of stearic acid at 70 ℃, into which tetrabutyl titanate and lead acetate were added while stirring. Then the solution was cooled in cool water to form a gel and the gel was calcined at different temperatures. The products were characterized by X-ray powder diffraction and infrared spectra analysis. The surface state was analyzed by means of X-ray photoelectron spectroscopy and surface photovoltage spectroscopy (SPS). The results show that the surface structure of nanocrystalline PbTiO3 is not integrate mainly due to the existence of oxygen cavities and most of the exposing atoms on the grain surface are metal ions. With the reducing of grain size, the oxygen cavity defect increases, the photovoltage effect on the surface enhances and the width of SPS becomes wider. The surface states of nanocrystalline materials have important influence on their dielectric properties and make the static state dielectric constant much bigger than that of bulk material.