Hydrothermal Syntheses, Structural Characterizations, and Photoluminescence Properties of Three Fluorinated Indium Phosphates With Bipyridyl Ligands: In3F2(2, 2-Bipy)2(HPO4)2(H1.5PO4)2, In2F2(H2O)(2, 2-Bipy)(HPO4)2, and In2F2(H2O)(2, 2-Bipy-5-Amine)(HPO4)2