Synthesis of ZrMo2O8 polymorphs by a melt quenching method and mechanochemical activation

This study presents two new approaches: the melt quenching method (up–down) and mechanochemical activation (down–up) for the preparation of single ZrMo2O8 polymorphs. A stoichiometric mixture of ZrO2 and MoO3 in a 1:2 molar ratio was subjected to melt quenching with different cooling rates and intense mechanical treatment in air using a planetary ball mill (Fritsch No. 7). The phases obtained and their transformations were monitored by X-ray diffraction (XRD), infrared (IR) spectroscopy and X-ray photoelectron spectroscopy (XPS). Trigonal (α) ZrMo2O8 is the first phase obtained by the melt quenching method. The same phase was prepared by mechanochemically assisted solid state synthesis. The additional heat-treatment led to phase transition to monoclinic (β) ZrMo2O8. It was established that these methods allowed a shorter synthesis time of ZrMo2O8 polymorphs as compared to the traditional solid state synthesis.