Gruneisen parameter and thermal expansion coefficients of NiSi<sub>2</sub>from first-principles

Niranjan, Manish K.; Kumar, Virendra; Karthikeyan, R.

doi:10.1088/0022-3727/47/28/285101

Cited by 8 publications

(4 citation statements)

References 36 publications

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“…The increase in LDA frequencies are primarily due to lower ground state volume predicted by LDA. 32,33 As can be seen in Table I, LDA ground state volume is~7% lower than that calculated using GGA. The computed frequencies can be seen to exist as four bands, in particular for AgNb 1/2 Ta 1/2 O 3 in Pbcm symmetry (see Fig.…”

Section: Theoretical Detailsmentioning

confidence: 80%

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Investigation of Raman Modes and Born‐Effective Charges in AgNb_1/2Ta_1/2O₃: A Density‐Functional and Raman Scattering Study

et al. 2015

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Using ab initio density‐functional theory, the Born‐effective charge tensors and zone‐center phonon mode frequencies are computed for AgNb1/2Ta1/2O3 in monoclinic P2/m and orthorombic Pbcm symmetries. The experimental mode frequencies are obtained from deconvolution of Raman spectrum of prepared AgNb1/2Ta1/2O3 samples and are compared with computed mode frequencies. The Raman modes with high (>350 cm−1) and low frequencies (<90 cm−1) correspond to Ag and O vibrations, respectively. The modes in intermediate frequency band (120–350 cm−1) are dominated by Nb(Ta)–O vibrations. The computed effective charge tensors of cations at A (Ag) and B (Nb, Ta) sites are found to be diagonal. The off‐diagonal components of charge tensor are found sizeable only for O ions in orthorhombic AgNb1/2Ta1/2O3 with Pbcm symmetry. Further, charge tensor structure of O ions is found to depend on site symmetry in the unit cell. Charge tensor components for Nb, Ta, and O ions differ significantly from their nominal ionic values suggesting (1) large local dipole moments induced by off‐centering of Nb(Ta) ions and tilting(rotations) of Nb(Ta)O6 octahedra, (2) hybridization between d‐orbitals of Nb(Ta) and p‐orbitals of O atoms. Furthermore, the electronic structure, directional dependence of effective charges and performance of LDA (GGA) exchange‐correlation functionals with regard to computed values are also discussed.

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Section: Theoretical Detailsmentioning

confidence: 80%

“…However, at ground state volume the LDA frequencies are higher than GGA frequencies by ~10 cm −1 . The increase in LDA frequencies are primarily due to lower ground state volume predicted by LDA . As can be seen in Table , LDA ground state volume is ~7% lower than that calculated using GGA.…”

Section: Theoretical Detailsmentioning

confidence: 85%

Investigation of Raman Modes and Born‐Effective Charges in AgNb_1/2Ta_1/2O₃: A Density‐Functional and Raman Scattering Study

et al. 2015

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“…The LDA and GGA are known to underestimate and overestimate the lattice constants, respectively. Furthermore, the lattice constant values computed within DFT framework correspond to temperature at 0 K. Thus, at higher temperature (T = 300 K), the computed values can be expected to increase by up to ∼0.2% due to lattice thermal vibrations [49].…”

Section: Resultsmentioning

confidence: 99%

Phase stability and elastic properties ofβTi–Nb–X(X= Zr, Sn) alloys: anab initiodensity functional study

Rajamallu

Niranjan

Ameyama

et al. 2017

Modelling Simul. Mater. Sci. Eng.

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Alloying effects of Zr and Sn on β phase stability and elastic properties in Ti–Nb alloys are investigated within the framework of first-principles density functional theory. Our results suggest that the stability of β phase can be significantly enhanced by the addition of Zr and Sn in Ti–Nb alloys. The computed results indicate that Zr and Sn behave as strong β stabilizers in the Ti–Nb system. The elastic properties are found to be altered considerably by the addition of ternary alloying elements (Zr and Sn). The computed elastic moduli of Ti18.75 at%Nb6.25 at%Zr and Ti25 at%NbxZr compositions are found to be lower than that for Ti18.75 at%Nb6.25 at%Sn and Ti25 at%NbxSn system. The lowest value of ∼54 GPa is obtained for Ti25 at%Nb6.25 at%Zr composition. Furthermore, the directional Young’s modulus is found to be in the order of E100 < E110 < E111 for all the compositions of Ti–Nb–Zr and Ti–Nb–Sn system.

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“…This effect is small for YNiGe 3 but is more pronounced for heavier rare earths as in the case of LuNiGe 3 . There were some small NiSi 2 crystallites attached to the surface of the crystals (a diamagnetic nonsuperconducting metallic silicide [39][40][41]) that could be easily removed by polishing. Besides Sn (T c = 3.7 K), no other superconducting impurity was detected, so we may claim that the superconducting transitions presented below are due to these new intermetallic compounds.…”

Section: Resultsmentioning

confidence: 99%

Superconductivity in monocrystalline YNiSi3 and LuNiSi3

et al. 2019

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We report the discovery of bulk superconductivity in the ternary intermetallics YNiSi 3 and LuNiSi 3. High-quality single crystals were grown via the Sn-flux method and studied using magnetization, specific-heat, and resistivity measurements at low temperatures. The critical temperatures obtained from these different techniques are in very good agreement and yield T c = 1.36(3) K and T c = 1.61(2) K for YNiSi 3 and LuNiSi 3 , respectively. Magnetization measurements indicate that both compounds are among the rare cases where type-I superconductivity occurs in a ternary intermetallic, however, the jump in the specific heat at the transition is lower than the value expected from BCS theory (C el /γ n T c = 1.43) in both materials and is equal to 1.14(9) and 0.71(5) for the Y and Lu compounds, respectively. Resistivity measurements exhibit sharp transitions but with critical fields μ 0 H c (0) (≈0.05 T for YNiSi 3 and ≈0.08 T for LuNiSi 3) considerably higher than those obtained from the magnetization and specific heat (≈0.01 T). First-principles density functional theory calculated electronic structure shows that these compounds have highly anisotropic and complex Fermi surfaces with one electronic and two holelike branches. One hole branch and the electron branch have a large cylindrical topology connecting the first Brillouin-zone boundaries, the former being built up by the hybridization of Y(Lu) d, Ni d, and Si p states, and the latter being built up by Ni d and Si p states. The calculated phononic structures indicate that the coupling of the Y(Lu), Ni d, and Si p electrons in the low-lying optical phonon branches is responsible for the formation of Cooper pairs and the observed superconducting state. Therefore, these compounds can be classified as anisotropic three-dimensional metals with multiband superconducting ground states in the weak-coupling regime.

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Gruneisen parameter and thermal expansion coefficients of NiSi₂from first-principles

Cited by 8 publications

References 36 publications

Investigation of Raman Modes and Born‐Effective Charges in AgNb_1/2Ta_1/2O₃: A Density‐Functional and Raman Scattering Study

Investigation of Raman Modes and Born‐Effective Charges in AgNb_1/2Ta_1/2O₃: A Density‐Functional and Raman Scattering Study

Phase stability and elastic properties ofβTi–Nb–X(X= Zr, Sn) alloys: anab initiodensity functional study

Superconductivity in monocrystalline YNiSi3 and LuNiSi3

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Gruneisen parameter and thermal expansion coefficients of NiSi2from first-principles

Cited by 8 publications

References 36 publications

Investigation of Raman Modes and Born‐Effective Charges in AgNb1/2Ta1/2O3: A Density‐Functional and Raman Scattering Study

Investigation of Raman Modes and Born‐Effective Charges in AgNb1/2Ta1/2O3: A Density‐Functional and Raman Scattering Study

Phase stability and elastic properties ofβTi–Nb–X(X= Zr, Sn) alloys: anab initiodensity functional study

Superconductivity in monocrystalline YNiSi3 and LuNiSi3

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Gruneisen parameter and thermal expansion coefficients of NiSi₂from first-principles

Investigation of Raman Modes and Born‐Effective Charges in AgNb_1/2Ta_1/2O₃: A Density‐Functional and Raman Scattering Study

Investigation of Raman Modes and Born‐Effective Charges in AgNb_1/2Ta_1/2O₃: A Density‐Functional and Raman Scattering Study