聚合物前驱体法制备铌酸钾钠薄膜

Preparation of K_(0.5)Na_(0.5)NbO_3 thin film by the polymeric precursor method

以加入和不加入草酸铵两种方法制备氢氧化铌。以碳酸钾、碳酸钠和制得的氢氧化铌为原料,柠檬酸为螯合剂,乙二醇为酯化剂,通过聚合物前驱体法在SiO2/Si基板上制备了铌酸钾钠(KNN)薄膜。研究了草酸铵的添加和不同退火温度对KNN薄膜性质的影响。结果显示:在pH=7.5,金属阳离子与柠檬酸摩尔比为1:3,柠檬酸与乙二醇的摩尔比为2:1时,可以获得均匀稳定的KNN前驱体溶胶。草酸铵的加入优化了薄膜的性能;随着退火温度的增加,薄膜的致密度越来越高。退火温度在850℃时,薄膜结晶性相对较好;900℃退火处理后,薄膜晶粒有定向生长趋势。

In this study, niobium hydroxide was synthesized with and without the addition of ammonium oxalate. And then, potassium-sodium niobate （KNN） films were prepared on the SiO2/Si substrate using the polymeric precursor method, with sodium carbonate, potassium carbonate as well as the obtained niobium hydroxide as raw materials, citric acid （CA） as chelating agent and ethylene glycol （EG） as esterification agent. The effects of ammonium oxalate addition and annealing temperatures on the properties of prepared KNN films were studied. The results show that homogeneous and stable KNN precursor sol is obtained when the pH value is 7.5, the molar ratio of metal cations to CA is 1 . 3 and the molar ratio of Ca to EG is 1 ~ 2. Addition of ammonium oxalate improves the properties of KNN films. With increasing annealing temperature, the density of KNN films increases. Compared with other KNN film samples, the sample annealed at 850℃ exhibits a better crystal structure. For the films annealed at 900 ℃, their crystal grains grow in a preferred direction.