Solid state synthesis of LiFePO4 studied by in situ high energy X-ray diffraction

The phase evolution and crystal structure transition of materials during solid-state synthesis of LiFePO4 were investigated by in situ high energy X-ray diffraction. It was found that the solid state reaction forming LiFePO4 started at a very low temperature, and LiFePO4 was clearly observed when the reaction temperature was above 173 °C. In situX-ray diffraction data also revealed that several impurities appeared when the reaction temperature was above 400 °C. These impurities were successfully indexed with ex situX-ray diffraction as Li3PO4, Fe2P, and Fe3P.