Zirconium tungstate hydroxide hydrate revisited: Crystallization dependence on halide and hydronium ions

• Published in: Journal of solid state chemistry Vol. 180; no. 12; pp. 3504 - 3509
• Main Authors: Colin, Julie A., Camper, DeMarco V., Gates, Stacy D., Simon, Monty D., Witker, Karen L., Lind, Cora
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.12.2007; Elsevier
• Subjects: BROMIDES; CHLORIDES; Condensed matter: structure, mechanical and thermal properties; Cross-disciplinary physics: materials science; rheology; CRYSTALLIZATION; Exact sciences and technology; Growth from solutions; HYDRATES; HYDROCHLORIC ACID; Hydrothermal; HYDROXIDES; Inorganic compounds; INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; KINETICS; Materials science; Methods of crystal growth; physics of crystal growth; New polymorph; OXONIUM IONS; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; THERMAL EXPANSION; Zirconium tungstate hydroxide hydrate; ZIRCONIUM TUNGSTATES; Kinetics; Zirconium tungstate hydroxide hydrate; Hydrothermal; New polymorph; Crystallization; Crystal growth; Cubic lattices; Hydroxides; Tungstates; Precursor; Thermal expansion; Hydrothermal synthesis; Halides; Chlorides; Counterions; Hydrates; Polymorphism; Crystal structure
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1016/j.jssc.2007.10.012

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 ZrW 2O 7(OH) 2·2H 2O. High temperatures, high acid concentrations, and the presence of chloride or bromide ions promote the formation of well-crystallized ZrW 2O 7(OH) 2·2H 2O. For low acid concentrations, a new zirconium tungstate hydrate polymorph is observed, which transforms to tetragonal ZrW 2O 7(OH) 2·2H 2O at longer reaction times. A study of crystallization kinetics in hydrochloric acid is presented. The formation of ZrW 2O 7(OH) 2·2H 2O 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 ZrW 2O 7(OH) 2·2H 2O. For low acid concentrations, a new zirconium tungstate hydrate polymorph is observed.