Standard Gibbs energy of formation of MgLa determined by solution calorimetry and heat capacity measurement from near absolute zero kelvin

The standard Gibbs energy of formation, ΔfGT°, of MgLa in the temperature range from near absolute 0 to 525 K were determined by calorimetry. The heat capacities, Cp, from 2 K to 525 K were measured by the relaxation method and DSC. Also, a thermal anomaly at 5.9 K, which appeared to be a superconductive phase transition, was found in the obtained Cp values. The ΔfGT°(MgLa) values were determined by combining the Cp data with the standard enthalpy of formation at 298 K which was measured by the Calvet-type calorimeter using hydrochloric acid solution. From 2 to 300 K, the ΔfGT° increases gradually, and it can be evaluated as a linear function of temperature above 300 K as follows:ΔfGT°(MgLa)(kJmol−1)=−39.236−6.9832×10−3T+2.1016×10−3TlogT+1.9114×10−5T2−0.81004T−1±7.40(2−300K),ΔfGT°(MgLa)(kJmol−1)=−41.100+9.9974×10−3T±7.40(300−525K).This result is expected to be useful as basic thermodynamic data of Mg-based alloys.