ELECTROCHEMICAL FORMATION AND CHARACTERIZATION OF MIXED VALENCE AND ABNORMAL VALENCE OXIDE FILMS

1.确定了La（III）-Cr（VI）体系电沉积前驱膜中异常价态Cr化合物LaCrO_4的形成条件。确定了LaCrO_4的热稳定区随温度、加热时间和氧分压的变化关系。LaCrO_4在500 ℃以下稳定，不受氧分压的影响，在室温真空下不分解.在150 ℃以上，LaCrO_4薄膜的电导率随温度的升高呈指数增长，表现出与半导体相似的性质。其电导率高于相同工艺制备的钙钛矿型LaCrO_3薄膜，但A位的价态控制对电导率没有影响.以硫酸铵和硫酸镁（MgSO_4）为电解液，采用阴极沉积法制备了混合价羟基氧化钼薄膜。MgSO_4是形成均匀、附着力强的薄膜所必需的组分.混合价羟基氧化钼薄膜是非晶态的，并且在200 ℃下加热12小时不会结晶。在4-10 μ m的IR区域中，在100 ℃下膜的分光光度发射率为约30-50%，并且对于大于10 μ m的更长波长，其增加到90%以上。膜在干燥或不干燥的情况下显示出导电性。这些特性表明，该薄膜是潜在的有用材料，用于许多目的，如远红外辐射器，传感器，红外探测器等。研究发现，在硝酸盐溶液中，阴极极化可形成Ce（III）-Ce（IV）等混合价稀土元素的凝胶状羟基氧化物膜。

1. Formation conditions of abnormal valence Cr compound LaCrO_4 from the precursor films electrodeposited from La (III) -Cr (VI) solutions were established. Thermally stable regions of LaCrO_4 were determined as functions of temperature, heating time and oxygen partial pressure. LaCrO_4 is stable below 500ﾟC independent of oxygen partial pressure and does not decompose in a vacuo at room temperature.2. Electric conductivity of LaCrO_4 film increased exponentially with temperature above 150ﾟC,indicating a similar property to semiconductors. The conductivity was higher than that of perovskite type LaCrO_3 film formed by the same process, but the valency control of A site showed no effect on the conductivity.3. Mixed valence molybdenum oxyhydroxide films were formed by cathodic deposition from solutions of ammonium molybdate and magnesium sulfate (MgSO_4). MgSO_4 was found to be a necessary component in the solution to from uniform and adhesive films.4. The mixed valence molybdenum oxyhydroxide films were amorphous and didn't crystallize by heating at 200ﾟC for 12 hours. Spectrophotometric emissivity of the films at 100ﾟC was about 30-50% in the IR region of 4-10 mum and it increased to more than 90% for longer wave length than 10 mum. The films showed electric conductivity with or without drying. These characteristics suggest that the films are potentially useful material for many purposes such as a far IR radiator, sensors, IR detectors, and so on.5. It was found that gel-like oxyhydroxide films of mixed valence rare-earch elements, such as Ce (III) -Ce (IV), can be formed by cathodic polarization in nitrate solutions of rare-earth elements.