Standard enthalpies of formation of selected Ni2YZ Heusler compounds

Abstract

The standard enthalpies of formation (Δ f H°) of selected ternary Ni-based Heusler compounds Ni 2 YZ (Y = Co, Cu, Fe, Hf, Mn, Ti, V; Z = Al, Ga, In, Si, Ge, Sn) were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation (in kJ/mole of atoms) of the Heusler structured (L2 1 , prototype Cu 2 MnAl, Pearson symbol cF16, space group Fm3 _ m) compounds are: Ni 2 MnGa (-29.8 ± 3.9); Ni 2 MnIn (-24.5 ± 2.0); Ni 2 MnSn (-29.7 ± 2.9); Ni 2 TiGa (-42.5 ± 2.2); Ni 2 TiIn (-28.5 ± 1.1); Ni 2 TiSn (-46.8 ± 2.0), for the B2 compound (prototype CsCl, Pearson cP2, space group Pm3 _ m): Ni 2 MnAl (-32.0 ± 2.8), for the inverse Heusler structured (i-L2 1 , prototype Li 2 AgSb, Pearson symbol cF16, space group F4 _ 3m) compound: Ni 2 CuSn (-12.5 ± 2.1), for the compounds of the L1 2 (prototype AuCu 3 , Pearson symbol cP4, space group Pm3 _ m) structure: Ni 2 CuAl (-38.9 ± 3.1); Ni 2 FeGe (-25.8 ± 3.0). Several off-stoichiometric alloys in the Ni-Mn-Sn system were also investigated: Ni 0.55 Mn 0.20 Sn 0.25 .7). Values are compared with those from first principles calculations in published papers and the Open Quantum Materials Database (OQMD). Lattice parameters were determined using X-ray diffraction analysis. Microstructures were characterized using scanning electron microscopy (SEM) with an energy dispersive spectrometer (EDS). Differential scanning © 2015. This manuscript version is made available under the Elsevier user license http://www.elsevier.com/open-access/userlicense/1.0/ 2 calorimetry (DSC) was used to measure the melting points of the compounds.

First-Principles Investigations of the Structural, Anisotropic Mechanical, Thermodynamic and Electronic Properties of the AlNi2Ti Compound

“…data from [48]; g Data calculated from the selected area electron diffraction pattern in [22]; h Exp. data from [49]; i Data from handbook [50]; j Exp. data measured by X-ray diffraction in [51]; k Exp.…”

Synthesis of Pure NiTiSn by Mechanical Alloying: An Investigation of the Optimal Experimental Conditions Supported by First Principles Calculations

“…However, the trend in the relative stability of the compounds remains the same between the two series of results. VASP calculated enthalpies considering an additional Hubbard term for the Ni-containing compounds are given in the figure; those omitting the U term are given in Table S2, Supplementary Material with the available experimental values [65,[67][68][69][70][71][72][73][74][75]. Note that all the results are in good agreement even if the GGA+U values are found elsewhere significantly to be more negative for NiTiSn and Ni 2 TiSn [62].…”

First-principles study of Zn-doping effects on phase stability and magnetic anisotropy of Ni-Mn-Ga alloys

“…The first step in the theoretical investigation of alloys is to find their thermodynamic stability represented by the enthalpy of formation at equilibrium volume and the site preference of doping atoms. The standard enthalpy of formation was obtained from theoretical formula [55]) and experimental results (−0.3089 eV/atom [56]). The site preference of substitutional atoms was determined by the lowest energy of formation.…”