Vaporization and deposition of cesium dimolybdate, Cs₂Mo₂O₇

Vaporization and deposition of cesium dimolybdate (Cs₂Mo₂O₇) in argon were studied by thermogravimetry and transpiration methods. From Raman spectra and electron probe microanalysis of deposits and inductively coupled plasma mass spectroscopy of the aqueous trap of the exhaust, it was judged that the Cs₂Mo₂O₇ vaporizes as Cs₂Mo₂O₇ (g). The effect of water addition on Raman spectral of Cs₂Mo₂O₇ was also investigated. Comparing the high-temperature mass losses of Cs₂Mo₂O₇ by thermogravimetry with that of Cs₂MoO₄, the equilibrium vapor pressure of Cs₂Mo₂O₇ was estimated. The vapor pressure of Cs₂Mo₂O₇ (l) in its liquid state was calculated to be: log₁₀P (Cs₂Mo₂O₇)(l) = (8.95 ± 0.07) - (1.03 ± 0.01) × 10⁴ /T (T = 1273-1573 K). The enthalpy of vaporization of Cs₂Mo₂O₇ (l) was estimated to be 197 ± 31 kJ·mol^-1. (author)