层状晶体结构铌酸盐KNb3O8粉体的凝胶–燃烧法合成与表征

Synthesis of KNb3O8 Powders with Layered Structure by a Gel-Combustion Method

摘要: 本文以水合氧化铌(Nb2O5•nH2O)为铌源，硝酸钾(KNO3)为钾源，采用柠檬酸凝胶–燃烧法合成了层状结构铌酸盐KNb3O8粉体。采用同步热分析仪(TG/DSC)分析了前驱体粉末的热分解过程。借助X射线衍射(XRD)和扫描电镜(SEM)对合成样品的物相组成及微观形貌进行了表征。结果表明，在600℃时KNb3O8开始结晶，粉体呈规则的条状。随着煅烧温度的升高，KNb3O8粉体的结晶度提高，形貌由条状逐渐过渡为类片状。

Abstract: The niobate (KNb3O8) powders with layered structure were successfully synthesized via the citric acid gel-combustion process using KNO3 and Nb2O5•H2O as the raw materials. Thermal behavior of the precursor was determined by TG-DSC techniques. The phase composition and morphology of the synthesized samples were characterized by using the X-ray diffraction and scanning transmission electron microscope. It was found that KNb3O8 phase was crystallized directly from the amorphous precursor at about 600˚C. The SEM images of the samples showed that the particles were bar-like under calcination temperature of 600˚C. However, the morphology of the particles transformed into flakes gradually as the calcination temperature increasing.