Crystal Form Controlled in Crystallization Processes of FePO4·2H2O
The controllable synthesis of different crystal forms of iron phosphate dihydrate was carried out,and the influence of the concentration of iron,oxidation time,oxidation temperature,aging and seed crystal on the crystal forms of FePO4·2H2O were comprehensively investigated.Results indicate that aging time have no effect on the crystal transformation,and pure crystal form of monoclinic FePO4·2H2O is obtained.Besides,the high purity of orthorhombic FePO4·2H2O could be obtained during the process such as lower concentration of iron,higher oxidation time,temperature or addition of seed crystal.The single crystal analysis indicates that the intramolecular hydrogen bond has effect on the thermodynamic stability of FePO4·2H2O,and the order of thermal stability is orthorhombic>monoclinic.
iron phosphate dihydratecrystal transformationmonoclinicorthorhombicthermodynamic stability