抄録
New synthesis route of the lanthanum germanate oxyapatite was successfully developed by a citrate combustion method from a homogeneous aqueous solution. The homogeneous solution can be prepared by dissolving lanthanum nitrate, germanium dioxide, dilute ammonia, and dilute nitric acid, and citric acid in water. From X-ray diffraction and thermogravimetric-thermal differential analyses, the lanthanum germanate oxyapatite was formed about 1003 K by a precursor prepared from the homogeneous solution. This oxyapatite-synthesis temperature is about 370 K lower than the temperature by conventional solid-state reaction and coprecipitation methods. Furthermore, control of the pH in the homogeneous aqueous solution was found to be important in order to prohibit the impurity formation.
