Dehydration of MoO3 · 2H2O: A Neutron Thermodiffractometry Study

✍ Scribed by N. Boudjada; J. Rodrı́guez-Carvajal; M. Anne; M. Figlarz

• Publisher: Elsevier Science
• Year: 1993
• Tongue: English
• Weight: 433 KB
• Volume: 105
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1993.1209

✦ Synopsis

A neutron powder thermodiffractometric study of the dehydration reactions (\mathrm{MoO}{3} \cdot 2 \mathrm{H}{2} \mathrm{O} \rightarrow) (\mathrm{MoO}{3} \cdot \mathrm{H}{2} \mathrm{O} \rightarrow \mathrm{MoO}{3}) has been carried out in order to investigate the topotactic mechanism previously reported. The topotactic character of the reactions is confirmed and an approximate model for the crystal structure of (\mathrm{MoO}{3} \cdot \mathrm{H}{2} \mathrm{O}) is proposed. Quantitative data about the relative amount of the existing phases, as a function of temperature, have been deduced from multiphase profile analysis. The anomalous behavior of the cell parameters of (\mathrm{MoO}{3} \cdot \mathrm{H}{2} \mathrm{O}), at about (100^{\circ} \mathrm{C}), indicates the existence of a new phase transition. The evolution of the crystallite size of (\mathrm{MoO}{3}) has also been obtained from the broadening of Bragg reflections at high temperature. The preferred direction of growth is along ([021]^{*}). 1993 Academic Press. Inc.