Vaporization rare earth sesquioxide

According to Ames et al. (1967) the vaporization of rare earth sesquioxides can be represented by the equation... 

Vaporization characteristics of rare earth metals and rare earth sesquioxides. 

It has been generally assumed that the rare-earth sesquioxides vaporize con-gruently with almost stoichiometric composition though a few studies (White et al. 1962, Ackermann and Rauh 1971, 1975) have shown small deviations (R2O2 99 to R2O2 995) from ideal stoichiometry. But this approximation had insignificant contribution to the reliability of the thermodynamic data of monoxides. 

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