Zirconium tungstate hydroxide hydrate revisited: Crystallization dependence on halide and hydronium ions |
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| Authors: | Julie A. Colin DeMarco V. Camper Stacy D. Gates Monty D. Simon Karen L. Witker Cora Lind |
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| Affiliation: | aDepartment of Chemistry, MS 602, The University of Toledo, Toledo, OH 43606, USA |
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| Abstract: | ![]()
The formation of zirconium tungstate hydroxide hydrate, a precursor to the negative thermal expansion material cubic zirconium tungstate, shows a strong dependence on hydrothermal reaction conditions. It was found that not only the acid concentration, but also the acid counterion plays a significant role in the crystallization of ZrW2O7(OH)2·2H2O. High temperatures, high acid concentrations, and the presence of chloride or bromide ions promote the formation of well-crystallized ZrW2O7(OH)2·2H2O. For low acid concentrations, a new zirconium tungstate hydrate polymorph is observed, which transforms to tetragonal ZrW2O7(OH)2·2H2O at longer reaction times. A study of crystallization kinetics in hydrochloric acid is presented. |
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| Keywords: | Zirconium tungstate hydroxide hydrate Crystallization Hydrothermal Kinetics New polymorph |
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