二水磷酸铁结晶过程的晶型可控研究

Crystal Form Controlled in Crystallization Processes of FePO_(4)·2H_(2)O

开展了不同晶型FePO_(4)·2H_(2)O的可控合成研究工作,重点研究了铁浓度、氧化时间、氧化温度、陈化时间和晶种等对FePO_(4)·2H_(2)O晶型的影响规律。结果表明:陈化时间对晶型转化不产生影响,均得到单一的单斜晶系FePO_(4)·2H_(2)O;随着铁浓度的降低,氧化时间/氧化温度的提高,或者晶种的引入,最终均得到纯相正交晶系FePO_(4)·2H_(2)O;单晶分析结果表明,分子内氢键影响着FePO_(4)·2H_(2)O产品的热力学稳定性,且构型稳定性为正交晶系>单斜晶系。

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 FePO_(4)·2H_(2)O were comprehensively investigated.Results indicate that aging time have no effect on the crystal transformation,and pure crystal form of monoclinic FePO_(4)·2H_(2)O is obtained.Besides,the high purity of orthorhombic FePO_(4)·2H_(2)O 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 FePO_(4)·2H_(2)O,and the order of thermal stability is orthorhombic>monoclinic.