Standard enthalpies of formation of some 3d transition metal gallides by high temperature direct synthesis calorimetry

The standard enthalpies of formation of some 3d transition metal gallides h ave been measured by high temperature direct synthesis calorimetry at 1373/-2 K. The following results in kJ/mol of atoms are reported: Sc5Ga3 (-59.4 +/-2.0); Ti2Ga (-39.0+/-1.4); V2Ga5 (-16.6+/-1.7); Cr3Ga (-11.8+/-1.8); FeG a3 (-24.8+/-2.1); CoGa3 (-29.4+/-2.2) and NiGa (-44.9+/-1.9). The results a re compared with some earlier values obtained by solution calorimetry or de rived from EMF measurements. They are also compared with predicted values f rom the semi-empirical model of de Beer et al. and with available enthalpie s of formation for 3d transition metal aluminides and germanides. (C) 1999 Elsevier Science S.A. All rights reserved.