Energetic evaluation of Ba– and Sr–Si clathrate formation at high pressures by first-principle pseudopotential calculations

Imai, Yoji; Watanabe, Akio

doi:10.1016/j.intermet.2009.10.003

Cited by 13 publications

(11 citation statements)

References 19 publications

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“…The phase stability of clathrates can be estimated by comparison of the ground-state energies. 36,37 The heat of formation of Ba 8 Ni x □ y Si 46−x−y was computed on the basis of the total energies obtained from first principles electronic structure calculations by considering the following balance…”

Section: Heat Of Formation and Phase Stabilitymentioning

confidence: 99%

Synthesis, Crystal Structure, and Physical Properties of the Type-I Clathrate Ba_8−δNi_x□_ySi_46–x–y

et al. 2012

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Type-I clathrate phase Ba(8)Ni(x)□(y)Si(46-x-y) (□ = vacancy) was obtained from the elements at 1000 °C with the homogeneity range 2.4 ≤ x ≤ 3.8 and 0 ≤ y ≤ 0.9. In addition, samples with low Ni content (x = 1.4 and 1.6; y = 0) and small Ba deficiency were prepared from the melt by steel-quenching. Compositions were established by microprobe analysis and crystal structure determination. Ba(8-δ)Ni(x)□(y)Si(46-x-y) crystallizes in the space group Pm ̅3n (No. 223) with lattice parameter ranging from a = 10.3088(1) Å for Ba(7.9(1))Ni(1.4(1))Si(44.6(1)) to a = 10.2896(1) Å for Ba(8.00(3))Ni(3.82(4))Si(41.33(6)). Single-crystal X-ray diffraction data together with microprobe analysis indicate an increasing number of framework vacancies toward compositions with higher Ni content. For all compositions investigated, Ni K-edge X-ray absorption spectroscopy measurements showed an electronic state close to that of elemental Ni. All samples exhibit metallic-like behavior with moderate thermopower and low thermal conductivity in the temperature range 300-773 K. Samples with compositions Ba(7.9(1))Ni(1.4(1))Si(44.6(1)) and Ba(7.9(1))Ni(1.6(1))Si(44.4(1)) are superconducting with T(c) values of 6.0 and 5.5 K, respectively.

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Section: Heat Of Formation and Phase Stabilitymentioning

confidence: 99%

Synthesis, Crystal Structure, and Physical Properties of the Type-I Clathrate Ba_8−δNi_x□_ySi_46–x–y

et al. 2012

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“…The calculation method is similar to that used in previous studies of alkalineearth metal silicides [7][8][9]; calculations were performed using CASTEP (Cambridge Serial Total Energy Package) developed by Payne et al [10]. This is a first-principles pseudopotential method based on density-functional theory (DFT) that describes the electron-electron interaction with a pseudopotential description of the electron-core interaction and a plane-wave expansion of the wavefunctions.…”

Section: Calculation Methodsmentioning

confidence: 99%

“…5(a). For the substitution by three Mg atoms in the pure Ca 8 -Si 4 unit cell, we calculated the case in which only one Ca in a 4c (2) site remains and the other three Ca 4c (2) sites are substituted by Mg atoms, as shown in Fig. 5(b).…”

Section: Multiplicity Andmentioning

confidence: 99%

Energetic prediction of Mg2Si–Ca2Si pseudobinary system using first-principles calculations

Imai

Mori

Nakamura

et al. 2013

Journal of Alloys and Compounds

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“…In contrast, only a small number of ternary strontium compounds have been reported, and the corresponding binary strontium clathrate of silicon remained experimentally inaccessible so far . Moreover, computational studies ruled out the stability of Sr 8 Si 46 in the pressure range from 0.1 MPa (ambient) up to 15 GPa . We obtain this clathrate by high‐pressure high‐temperature synthesis at 5 GPa and at temperatures between 1273 and 1373 K. In this work, we report the crystal structure, chemical bonding and superconductivity of the binary strontium clathrate Sr 8 Si 46 .…”

Section: Introductionmentioning

confidence: 95%

“…[33] Moreover,computational studies ruled out the stability of Sr 8 Si 46 in the pressure range from 0.1 MPa (ambient) up to 15 GPa. [34,35] We obtain this clathrate by high-pressureh igh-temperature synthesis at 5GPa and at temperatures between 1273 and 1373K.I nt his work, we report the crystal structure, chemical bonding and superconductivity of the binary strontium clathrate Sr 8 Si 46 .…”

Section: Introductionmentioning

confidence: 97%

In‐Cage Interactions in the Clathrate Superconductor Sr₈Si₄₆

Hübner¹,

Prots²,

Schnelle³

et al. 2019

Chemistry A European J

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The clathrate Is uperconductor Sr 8 Si 46 is obtained under high-pressureh igh-temperature conditions, at 5GPa and temperatures in the range of 1273 to 1373 K. At ambient pressure, the compound decomposes upon heatinga t T = 796(5) Ki nto Si and SrSi 2 .T he crystal structure of the clathrate is isotypic to that of Na 8 Si 46 .C hemical bonding analysisr eveals conventionalc ovalent bondingw ithin the silicon network as well as additional multi-atomic interactions between Sr and Si within the framework cages. Physical measurements indicateabulk BCS type II superconducting state below T c = 3.8(3) K.

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Energetic evaluation of Ba– and Sr–Si clathrate formation at high pressures by first-principle pseudopotential calculations

Cited by 13 publications

References 19 publications

Synthesis, Crystal Structure, and Physical Properties of the Type-I Clathrate Ba_8−δNi_x□_ySi_46–x–y

Synthesis, Crystal Structure, and Physical Properties of the Type-I Clathrate Ba_8−δNi_x□_ySi_46–x–y

Energetic prediction of Mg2Si–Ca2Si pseudobinary system using first-principles calculations

In‐Cage Interactions in the Clathrate Superconductor Sr₈Si₄₆

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Energetic evaluation of Ba– and Sr–Si clathrate formation at high pressures by first-principle pseudopotential calculations

Cited by 13 publications

References 19 publications

Synthesis, Crystal Structure, and Physical Properties of the Type-I Clathrate Ba8−δNix□ySi46–x–y

Synthesis, Crystal Structure, and Physical Properties of the Type-I Clathrate Ba8−δNix□ySi46–x–y

Energetic prediction of Mg2Si–Ca2Si pseudobinary system using first-principles calculations

In‐Cage Interactions in the Clathrate Superconductor Sr8Si46

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Synthesis, Crystal Structure, and Physical Properties of the Type-I Clathrate Ba_8−δNi_x□_ySi_46–x–y

Synthesis, Crystal Structure, and Physical Properties of the Type-I Clathrate Ba_8−δNi_x□_ySi_46–x–y

In‐Cage Interactions in the Clathrate Superconductor Sr₈Si₄₆