(中南大学 化学化工学院， 长沙 410083)
摘 要: 研究了超声波作用下钼酸铵溶液的结晶过程，揭示了超声波对四钼酸铵晶型的影响规律。研究表明，在无超声波作用下生成β型四钼酸铵的反应需1～2d，在超声波作用下只需十几分钟即可完成，并且发生晶型改变，生成了微粉型四钼酸铵。在实验基础上提出了钼酸铵溶液结晶的可能途径，并在RHF/3-21G和STO-3G水平上，对超声波作用下钼酸铵溶液结晶过程中所涉及到的H2Mo7O4-24， H8Mo8O4-30，(MoO2)(MoO3)x-1］2+(x=1，2，3)，(NH4)4Mo8O26等进行量子化学从头计算，得到各研究体系的总能量和集居数。计算结果表明，当pH值为2.3～2.5时，超声波产生的特殊的“超声效应”可能使钼酸铵溶液中的H2Mo7O4-24变成［(MoO2)(MoO3)x-1］2+(x=1，2，3)，从而生成微粉型四钼酸铵。
关键字: 超声波；钼酸铵溶液；结晶；量子化学从头计算
molybdate solution under ultrasonic
（College of Chemistry and Chemical Engineering,
Central South University, Changsha 410083, China）
Abstract:The crystallization process of ammonium molybdate solution under ultrasonic was studied. The crystalline under ultrasonic were detected. It is indicated that ultrasonic has a great effect on the process of preparation β-type ammonium tetramolybdate. The crystallization time is shortened from 1～2d to 10～20min under ultrasonic and the crystalline converts into microcrystal-type under ultrasonic. The total energy and condensation of atoms of H2Mo7O4-24, H8Mo8O4-30, ［MoO2)(MoO3)x-1 ］2+(x=1，2，3) and (NH4)4Mo8O26 were computed at the HF/3-21G, STO-3G level. The calculation results show that the transformation from H2Mo7O4-24 to ［(MoO2)(MoO3)x-1］2+(x=1，2，3) at pH 2.3～2.5 is the reason of crystallization of microcrystal-type under ultrasonic.
Key words: ultrasonic; ammonium molybdate solution; crystallization; abinitio
