Standard enthalpies of formation of some lanthanide gallides by high temperature direct synthesis calorimetry

The standard enthalpies of formation of some lanthanide metal gallides have been measured by high temperature direct synthesis calorimetry at 1373 +/- 2 K. The following results (in kJ/mole of atoms) are reported; CeGa2(-71.1 +/-2.6); PrGa2(-69.3 +/-2.7); NdGa2(-72.1 +/-1.8); SmGa,(-73.7 +/-2.3); GdG a2(-72.8 +/-2.8); TbGa2(-72.3 +/-2.4); DyGa3(-52.5 +/-2.0); HoGa3(-56.8 +/- 2.1); ErGa3(-51.6 +/-1.8); TmGa3(-53.9 +/-2.5); LuGa3(-52.2 +/-2.3). The re sults are compared with some earlier Values derived from EMF measurements. They are also compared with the predicted values of Miedema et al. [Calphad 7 (1983) 51]. We will also compare our measured enthalpies of formation wi th the predictions by Gschneidner [J. Less Common Metals 17 (1969) 1; Metal s Mater. Processes 1 (1990) 241] for lanthanide alloys. (C) 2001 Elsevier S cience B.V. All rights reserved.