Standard enthalpies of formation of selected Ru2YZ Heusler compounds

• Standard enthalpies of formation of Ru2YZ were measured using a drop calorimeter.
• Result of L21 structured compounds agrees with first principles data.
• Lattice parameters and related phase relationships were consistent with literature data.
• Ru2HfSn, Ru2TiSn, Ru2VGa, Ru2VSi, Ru2VSn of L21 structure were reported for the first time.

The standard enthalpies of formation of selected ternary Ru-based Heusler compounds Ru2YZ (Y = Fe, Hf, Mn, Ti, V; Z = Al, Ga, In, Si, Ge, Sn) were measured using high temperature direct reaction calorimetry. The measured enthalpies of formation (in kJ/mole of atoms) of the Heusler compounds are, Ru2FeGe (−19.7 ± 3.3); Ru2HfSn (−24.9 ± 3.6); Ru2MnSi (−46.0 ± 2.6); Ru2MnGe (−29.7 ± 1.0); Ru2MnSn (−20.6 ± 2.4); Ru2TiSi (−94.9 ± 4.0); Ru2TiGe (−79.1 ± 3.2); Ru2TiSn (−60.6 ± 1.8); Ru2VSi (−55.9 ± 1.7);for the B2-structured compounds, Ru2FeSi (−28.5 ± 0.8); Ru2HfAl (−70.8 ± 1.9); Ru2MnAl (−32.3 ± 1.9); Ru2MnGa (−25.3 ± 3.0); Ru2TiAl (−62.7 ± 3.5); Ru2VAl (−30.9 ± 1.6); Ru2ZrAl (−64.5 ± 1.5). Values were compared with those from published first principles calculations and the OQMD (Open Quantum Materials Database). Lattice parameters of these compounds were determined using X-ray diffraction analysis (XRD). Microstructures were identified using scanning electron microscopy (SEM) and Energy Dispersive Spectroscopy (EDS).