Standard enthalpies of formation of selected XYZ half-Heusler compounds |
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Affiliation: | 1. School of Material Science and Engineering, Hebei University of Technology, Tianjin 300130, PR China;2. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, PR China;1. School of Physics, Tonghua Normal University, Tonghua, 134002, PR China;2. Department of Physics, College of Science, North China University of Science and Technology, Tangshan, 063009, PR China;1. ICGM-Université de Montpellier II, UMR-CNRS 5253, Pl. E. Bataillon CC1506, Montpellier 34095, France;2. Department Electrical & Electronic Engineering, ITMO University Lomonosova ul. 9, St. Petersburg 191002, Russia;1. Condensed Matter Theory Group, School of Studies in Physics, Jiwaji University, Gwalior 474 011, M.P., India;2. Department of Physics, Govt. K.R.G. Auto. P.G. College, Gwalior 474 001, M.P., India;1. Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30, D-48149 Münster, Germany;2. Institut für Physikalische Chemie, Universität Münster, Corrensstrasse 30, D-48149 Münster, Germany;3. New Chemistry Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India |
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Abstract: | The standard enthalpies of formation of selected ternary half-Heusler type compositions XYZ (X = Au, Co, Fe, Ir, Ni, Pd, Pt, Rh, Ru; Y = Hf, Mn, Ti, Zr; Z = Ga, Sn) were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation (in kJ/mole of atoms) of the half-Heusler compounds (prototype MgAgAs, Pearson symbol cF12, space group F-43m) are, IrMnSn (−29.4 ± 1.8); NiTiSn (−52.6 ± 2.4); PtHfSn (−98.8 ± 3.4); PtMnSn (−55.8 ± 2.6); PtTiSn (−93.6 ± 3.3); PtZrSn (−104.9 ± 3.8); for the B2 compound (prototype CsCl, Pearson symbol cP2, space group Pm-3m), RuMnGa (−26.9 ± 1.7); for the C1 structured (prototype CaF2, Pearson symbol cF12, space group Pm-3m) or the C1b structured compound IrMnGa (−40.9 ± 1.7). Indicative standard enthalpies of formation of the following compounds were obtained, half-Heusler compounds AuMnSn, CoTiSn, IrZrSn, NiHfSn, NiZrSn, PdHfSn, PdZrSn, RhTiSn; Heusler compound (prototype Cu2MnAl, Pearson symbol cF16, space group Fm-3m) RhMnSn; hexagonal compound (prototype BeZrSi, Pearson symbol hP6, space group P63/mmc) PtMnGa and another type of hexagonal compound (prototype RhHfSn, Pearson symbol hP18, space group P-62c) RhHfSn, IrZrsn, RhZrSn. Values were compared with ab initio calculations from AFLOW and OQMD. Lattice parameters of these compounds were determined using X-ray diffraction (XRD) analysis. Microstructures were characterized using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Selected alloys were further annealed to investigate phase transformations and phase relationships. |
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Keywords: | Half-Heusler compound Standard enthalpy of formation Calorimetry |
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