Preparation of Ferroelectric Films by the Sol-Gel Method

从金属醛氧化物出发的溶胶-凝胶法制备各种氧化膜是一种很有前途的方法。本研究建立了在PbTiO_3-PbZrO_3体系中形成铁电薄膜的溶胶-凝胶工艺。在此过程中遇到的一个问题是，这些钛和锆的烷氧化物很容易氢化。研究了烷基氧化物的稳定性，并用稳定的烷基氧化物制备了PbTiO_3-PbZrO_3薄膜。通过本研究得到了以下结果：(1)在干燥气氛下，以极易水解的Zr-或b -烷氧化物为原料，制备了含ZrO_2或b_2o_3的多组分薄膜。(2) Al， Ti或Zr的金属醇氧化物已被发现与螯合剂如β -二酮稳定。从相应金属的稳定的烷氧化物中获得了非常均匀的Al_2O_3， TiO_2或ZrO_2膜。(3)以Ti(O-nBu)_4和Zr(O-nBu)_4为原料，经乙酰丙酮稳定制备了PbTiO_3-PbZrO_3体系的铁电薄膜。所得薄膜在400℃以下为无定形，在500℃热处理后结晶，随着热处理温度的升高，薄膜的结晶度增大，同时伴随着介电常数的增大。随着PbZrO_3含量的增加，PbTiO_3-PbZr/_3体系中膜的介电常数减小。

The sol-gel method which starts from metal-aldoxides is a promising process to prepare various oxide films. The present study has been carried out to establish the sol-gel process to form ferroelectric films in the system PbTiO_3-PbZrO_3. One of the problems encountered in the process is that these alkoxides of Ti and Zr is easily hydrohyzable. The stabilization of the alkoxides has been examined and then the PbTiO_3-PbZrO_3 films has been prepared from the stabilized alkoxides. The following results have been obtained through the present study: (1) ZrO_2 or B_2O_3-containing multicomponent films have been prepared from very hydrolyzable Zr- or B-alkoxides by carrying out the coating in a dry atmosphere. (2) Metal alkoxides of Al, Ti, or Zr have been found to be stabilized with chelating agents such as betha-diketones. Very homogeneous Al_2O_3, TiO_2, or ZrO_2 films have been obtained from the stabilized alkoxides of corresponding metals. (3) Ferroelectric films in the system PbTiO_3-PbZrO_3 have been prepared from Ti(O-nBu)_4 and Zr(O-nBu)_4 stabilized with acetyleacetone. The films obtained are amorphous below 400 c and crystallized by the heat-treatment at 500 c. The crystallinity of the films is increased with increasing heat-treatment temperature, accompanying the increase in dielectric constant. The dielectric constant of the films in the system PbTiO_3-PbZr/_3 decreases as the content of PbZrO_3 is increased.