| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1331122 | Journal of Solid State Chemistry | 2007 | 6 Pages |
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.
Graphical abstractThe formation of ZrW2O7(OH)2·2H2O shows a strong dependence on reaction conditions. Both acid concentration and acid counterion play a significant role in the crystallization. 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.Figure optionsDownload full-size imageDownload as PowerPoint slide
