COMPARATIVE ANALYSIS FOR SATURATED VAPOUR PRESSURE OF RARE EARTH FLUORIDES AND BROMIDES
This paper deals with saturated vapor pressure determination for several rare earth halides. Vapor pressure definition is a time-consuming and complicated task because of fluorides and bromides high infusibility. Therefore, saturated vapor pressures are mainly investigated in a rather narrow temperatures range (about 100-150K). The methods of relative calculations (MRC) used in the work involved enable to calculate vapor pressure in wide temperature intervals. For research the following rare earth fluorides and bromides were chosen: LaF3, YF3, ScF3, LaBr3, CeBr3, PrBr3, NdBr3, YBr3, HoBr3, LuBr3, TbBr3, GdBr3. The reliable and well-studied substance, namely CaF2, was selected as a tetrad one for analyses of rare earth fluorides and bromides vapour-pressure. According with the task we examined published data on vapor pressure substances chosen. Using the least square method (LSM) the saturated vapour pressure dependences both on temperature and on tetrad saturated vapor pressure were obtained and their diagrammes were made. Conclusions: by means of MRC we extended temperature intervals for rare earth halides up to 400 K without additional experimental work. So, application of MRC is very usefull for extention of temperature range of experimental data.