凝胶燃烧法制备KNbO_3纳米粉体

Synthesis of Nanocrystalline KNbO_3 Powder by Gel-Combustion Method

以自制的水合氧化铌(Nb2O.5nH2O)为铌源,硝酸钾(KNO3)为钾源,采用柠檬酸凝胶-燃烧法制备出铌酸钾(KNbO3,KN)粉体。通过TG/DSC研究了前躯体粉末的热分解过程;借助XRD和TEM对样品的晶体结构、微观形貌和粒径进行了表征。结果表明,过多的柠檬酸和羧酸盐在330℃附近分解成碳酸盐,在600℃时KN相开始形成,没有中间相产生。煅烧温度大于600℃即可获得分散良好、粒度均匀、形状规则的纳米KN粉体。随着煅烧温度的升高,KN粉体的结晶度提高,颗粒增大。

Potassium niobate（KNbO3） powder was successfully synthesized via the citric acid gel-combustion process by using KNO3 and Nb2O5·H2O as the raw materials.Nb2O5·H2O was obtained at first.Thermal behavior of the precursor was determined by TG-DSC technique.The structure,morphology and size of samples were characterized by the X-ray diffraction and the transmission electron microscope.It was found that excess citric acid and carboxylate mixture decomposed at about 330℃ to form carbonate.KN phase was supposed to nucleate directly from the amorphous precursor at about 600℃ without the formation of any intermediate phase.The powders calcined at temperature higher than 600℃ were uniform,well dispersed and regular nanoparticles.The grain sizes and crystallinity ascend with the calcination temperature increasing.