Electrochemical, hydrothermal, and electrochemical-hydrothermal synthesis of barium titanate thin films on titanium substrates
Electrochemical, hydrothermal, and electrochemical-hydrothermal synthesis of barium titanate thin films on titanium substrates
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DOI：
10.1557/jmr.1992.0423
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发表时间：
1992-02
影响因子：
2.7
通讯作者：
R. Bacsa;P. Ravindranathan;J. Dougherty
中科院分区：
文献类型：
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作者：
R. Bacsa;P. Ravindranathan;J. Dougherty
在80°C−200°C温度范围内，钛金属与BaO_2饱和溶液发生电化学反应、水热反应和电化学-水热反应，在钛金属衬底上制备了结晶良好的立方BaTiO_3多晶薄膜。在pH=13，电流密度为10~50 mA/cm~2的条件下，钛衬底在BA(OH)_2溶液中进行阳极氧化，在没有偏压的情况下，也可以通过BA(OH)_2与钛衬底的水热反应制备薄膜。这两种技术的结合将反应时间缩短到30-45分钟。结果表明，该膜具有良好的附着力，在45min的反应时间内可形成厚度达2μm的膜。电容测量得出的介电常数为300。比较了三种不同工艺制备的薄膜的结晶度和微观结构。薄膜厚度随反应温度和反应时间的增加而增加。在一定温度下，随着反应时间的延长，结晶度降低。反应中间体很可能是氢氧化钛(Aq.)在这三种情况下都有生成，这导致了结晶BaTiO_3的形成。
Well-crystallized polycrystalline films of cubic BaTiO_3 have been synthesized on Ti metal substrates by electrochemical, hydrothermal, and electrochemical-hydrothermal reaction of a Ti metal with a saturated solution of Ba(OH)_2 in the temperature range 80 °C−200 °C. The films can be produced in the electrochemical process by the anodization of a Ti substrate in Ba(OH)_2 solution at pH = 13 and current densities of the order of 10–50 mA/cm^2. The films can also be synthesized by the hydrothermal reaction of Ba(OH)_2 and a Ti substrate without electrical bias. A combination of these two techniques reduces the reaction time to 30–45 min. The films were found to have good adherence on the substrate and films of thickness up to 2 μm could be formed within a reaction time of 45 min. Capacitance measurements have yielded a dielectric constant of 300. The films prepared by the three different techniques have been compared for crystallinity and microstructure. The thickness of the films increased with temperature and time of reaction. The crystallinity decreased with extended time of reaction for a given temperature. It is likely that a reactive intermediate such as Ti(OH)_4 (aq.) is formed in all the three cases which leads to the formation of crystalline BaTiO_3.