X-ray study of crystal structure and pressure dependence of the Néel temperature of the GdRh2Si2 and TbRh2Si2 compounds
Abstract Powder X-ray diffraction measurements on intermetallic compounds RERh 2 Si 2 ( RE = Gd , Tb ) have been made in the temperature range of 78 to 300K. Below T N both samples show significant volume expansion with the coefficient δV V being as large as 5.54·10 -4 and 6.2·10 -4 for RE = Gd , Tb , respectively. The Neel temperature decreases with increasing applied pressure in GdRh 2 Si 2 , but it remains constant for TbRh 2 Si 2 .
Equations have been developed for describing the isotherms of extraction of rare-earth metal(III) [REM(III)] nitrates from aqueous concentrated solutions by 100% diisoamyl methylphosphonate, taking into account the variation of activity coefficients of components in the organic phase when its composition is varied within broad limits. The thermodynamic parameters of the extraction equilibria have been calculated using as the standard states hypothetical one-molal aqueous REM(III) nitrate solutions and pure components of the organic phase at a mole fraction of 1.0.