改进的低温固相法制备钙钛矿型KTaO3

采用改进的固相法, 以K2CO3和氢氧化钽为原料, 通过添加KF, 在相对低温下制备了单一钙钛矿结构的KTaO3. KF的加入抑制了烧绿石相的生成, 通过水洗可脱除KF. 使用X射线衍射仪(XRD), 扫描电子显微镜(SEM)和紫外-可见(UV-Vis)漫散射光谱仪对不同温度下制备的产物进行了表征. 结果表明, 各个温度下制备的产物均是由粒径在10~30 nm范围内的粒子聚集成的大颗粒; 500, 600和800℃制备的产物带隙分别为3.68, 3.63和3.54 eV. 进一步考察其它碱金属卤化物对产物结构的影响发现, LiF, NaF和KF的作用相同; 当添加碱金属氯化物时, 主要产物分别是钽酸锂、 钽酸钠和烧绿石结构的钽酸钾.

Perovskite-type KTaO3 Prepared by a Modified Solid-state Method at Low Temperature

Perovskite-type KTaO3 powder was synthesized by a modified solid-state method at relatively low temperature using K2CO3 and ammonium tantalum hydroxide as starting materials with the addition of KF which was then washed off with water. X-Ray diffraction(XRD), scanning electron microscopy(SEM) and UV-Vis spectrometry were used to characterize the products calcined at different temperatures. The results showed that KF could inhibit the formation of pyrochlore phase and the products obtained at different temperature were agglomerations which were made up of many small grains with 10-30 nm in diameter, the band gap of samples calcined at 500, 600 and 800℃ were 3.68, 3.63 and 3.54 eV, respectively. The influences of other alkali halides were also investigated. The results indicated that lithium fluoride and sodium fluoride played the same role as potassium fluoride did. When using alkali chloride as additive, the major products were lithium tantalate, sodium tantaltate and pyrochlore potassium tantatate, respectively.