退火温度对IrO_2+ZrO_2涂层结构和电容性能的影响

采用热分解法在Ti基上被覆了IrO_2+ZrO_2氧化物涂层。通过XRD、SEM、EDX、XPS和循环伏安法等分析了退火温度对IrO_2-ZrO_2二元氧化物涂层的物相、表面形貌和电容性能的影响,引用非线性方程q~*(v)=A_1exp~(-v/t_1)+A_2exp~(-v/t_2)+y_0计算了涂层的内外活性点。结果表明:IrO_2-ZrO_2涂层的临界晶化温度为340~360℃,340℃退火的涂层物相为非晶结构,360℃退火,含有晶态和非晶态2种结构组织,其离子价态为Ir~(3+)、Ir~(4+)以及过饱和IrO_(2+x)(x0)。电容性能随着温度的升高呈先增大后减小变化,360℃退火的电极有最大的电容值,与其"非晶态/晶态"两相共存组织结构有关。涂层中质子迁移能力比电子导电能力对电容的影响要大,扫描速度对质子迁移的影响大于对电子导电的影响。

Influence of Annealing Temperature on the Structures and Capacitive Performance of IrO2+ZrO2 Binary Oxide Coatings

IrO2+ZrO2 binary oxide coatings deposited on Ti substrate were prepared by thermal decomposition. The influence of the annealing temperature on the structure, surface morphology, surface composition, and capacitive performance was tested by XRD, SEM, EDX, XPS, CV, etc. The nonlinear equation q*(v)=A1exp(-v/t1)+A2exp(-v/t2)+y0 was used to calculate the active sites located inside and outside of the coatings. The results show that the critical crystallization temperature of IrO2-ZrO2 is between 340~360 °C. The phase of the coating annealed at 340 °C still remains amorphous. While annealing at 360 °C, the coatings contain both crystalline and amorphous structures. They have typical crack-like morphology and Ir3+, Ir4+, as well as higher valence Ir atoms. The specific capacitance increases with the increasing of temperature up to 360 °C, and then decreases with further increasing temperature. The electrodes annealed at 360 °C have the highest specific capacitance probably due to the optimal structures of "amorphous/crystalline mixture" which favor both electron and proton conductivity. The proton transfer has a greater influence on the capacitance than electronic conductivity. The effect of the CV scanning speed on proton migration is greater than that on electronic conductivity