Gap at the Fermi level and magnetism in RMSn ternary compounds (R = Ti, Zr, Hf and M = Fe, Co, Ni)

Kuentzler, R.; Clad, R.; Schmerber, G.; Dossmann, Y.

doi:10.1016/0304-8853(92)91629-8

Cited by 63 publications

(30 citation statements)

References 4 publications

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“…This trend is consistent with a similar increase in phonon DOS at low frequencies with increasing transition metal mass. The calculated Debye temperature match reasonably well with experiment 44,45 as shown in Table 2. …”

Section: Phonon Density Of States and Thermal Propertiessupporting

confidence: 83%

Phase separation of full-Heusler nanostructures in half-Heusler thermoelectrics and vibrational properties from first-principles calculations

et al. 2015

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Abstract:Previous studies have indicated that the figure of merit (ZT) of half-Heusler (HH) alloys with composition MNiSn (M = Ti, Zr, or Hf) is greatly enhanced when the alloys contain a nano-scale full-Heusler (FH) MNi 2 Sn second phase. However, the formation mechanism of the FH nano-structures in the HH matrix and their vibrational properties are still not well understood. We report on first principles studies of thermodynamic phase equilibria in the MNiSn-MNi 2 Sn pseudo-binary system as well as HH and FH vibrational properties. Thermodynamic phase diagrams as functions of temperature and Ni concentration were developed using density functional theory (DFT) combined with a cluster expansion and Monte Carlo simulations. The phase diagrams show very low excess Ni solubility in HH even at high temperatures, which indicates that any Ni excess will decompose into a two-phase mixture of HH and FH. Vibrational properties of HH and FH alloys are compared. Imaginary vibrational modes in the calculated phonon dispersion diagram of TiNi 2 Sn indicate a dynamical instability with respect to cubic [001] transverse acoustic modulations. Displacing atoms along unstable vibrational modes in cubic TiNi 2 Sn reveal lower energy structures with monoclinic symmetry. The energy of the monoclinic structures are found to depend strongly on the lattice parameter. The origin of the instability in cubic TiNi 2 Sn and its absence in cubic ZrNi 2 Sn and HfNi 2 Sn is attributed to the small size of the Ti 3d shells compared to Zr and Hf atoms. Lattice constants and heat capacities calculated by DFT agree well with experiment.

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Section: Phonon Density Of States and Thermal Propertiessupporting

confidence: 83%

Phase separation of full-Heusler nanostructures in half-Heusler thermoelectrics and vibrational properties from first-principles calculations

et al. 2015

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“…In going from the binary substructure of NdBi to the ternary NdBiPt, one would expect, in analogy with ZrNiSn, that the addition of Pt to the NdBi substructure would ''increase the gap,'' that is, decrease the overlap of the bands, and this may be the case since our experimental results for NdBiPt indicate only a very small overlap and concentrations of approximately 10 18 cm…”

Section: ϫ3mentioning

confidence: 89%

“…Another recently discovered class of materials exhibiting unusual transport and optical properties are the ternary intermetallics of the form MNiSn ͑MϭTi, Zr, or Hf͒. [7][8][9][10] These properties seem to imply the existence of a gap at the Fermi level on the order of 0.1-0.2 eV. The MNiSn system is a subset of a larger family of compounds possessing the MgAgAs ͑AlLiSi͒ structure, of which over 100 different compounds are known.…”

Section: Introductionmentioning

confidence: 99%

Low-temperature transport properties of NdBiPt

1996

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NdBiPt is a member of a new class of ternary intermetallic semiconductors and semimetals. These materials are covalently bonded crystals with band gaps expected to be in the range of 0-1 eV. Longitudinal resistivity, Hall resistivity, and thermoelectric power measurements reveal that in NdBiPt the ''gap'' is an overlap that gives rise to a semimetallic behavior exhibiting high hole and electron mobilities. Keywords Physics and Astronomy Disciplines Condensed Matter Physics CommentsThis article is from Physical Review B 53 (1996) NdBiPt is a member of a new class of ternary intermetallic semiconductors and semimetals. These materials are covalently bonded crystals with band gaps expected to be in the range of 0-1 eV. Longitudinal resistivity, Hall resistivity, and thermoelectric power measurements reveal that in NdBiPt the ''gap'' is an overlap that gives rise to a semimetallic behavior exhibiting high hole and electron mobilities. ͓S0163-1829͑96͒04119-7͔

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“…The curves for the heat capacity as function of temperature and the C/T vs. T ' plot (inset) are given in [ 5 and 161 and 0.9 [ 7 ] mJ/mol K ' .…”

Section: B Experimental Results and Data Analysismentioning

confidence: 99%

“…where 8 is the angle of diffraction, and h is the wavelength of the x-ray beam and for the cubic system, d is given by Combining equations ( 7 ) and ( 8 ) and noting that Aa=a-a, we have…”

Section: A Growth Of T I N I S Nmentioning

confidence: 99%

Physical metallurgy and properties of TiNiSn and PtMnSb

Zhang

1997

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Gap at the Fermi level and magnetism in RMSn ternary compounds (R = Ti, Zr, Hf and M = Fe, Co, Ni)

Cited by 63 publications

References 4 publications

Phase separation of full-Heusler nanostructures in half-Heusler thermoelectrics and vibrational properties from first-principles calculations

Phase separation of full-Heusler nanostructures in half-Heusler thermoelectrics and vibrational properties from first-principles calculations

Low-temperature transport properties of NdBiPt

Physical metallurgy and properties of TiNiSn and PtMnSb

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