Electrons and phonons in the ternary alloyCaAl2−xSixas a function of composition

2005/09/09 by Matteo Giantomassi, Lilia Boeri, Giovanni B. Bachelet · 4 citations
Chemistry · Materials Science · Physics and Astronomy · #Alloy #Boron and Carbon Nanomaterials Research #Chemistry #Computer science #Condensed matter physics #Crystallography #Intermetallic #MXene and MAX Phase Materials #Materials science #Metallurgy #Phonon #Physics #Superconductivity #Superconductivity in MgB2 and Alloys #Ternary operation #cond-mat.mtrl-sci #cond-mat.supr-con

paper · pdf · doi:10.1103/physrevb.72.224512

arxiv created 2005/09/09 · openalex publication_date 2005/12/15 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05

Abstract

We report a detailed first-principles study of the structural, electronic, and vibrational properties of the superconducting C₃₂ phase of the ternary alloy CaAl_2\ensuremath-xSi_x, both in the experimental range 0.6\ensuremath\leqslantx\ensuremath\leqslant1.2, for which the alloy has been synthesized, and in the theoretical limits of high aluminum and high silicon concentration. Our results indicate that, in the experimental range, the dependence of the electronic bands on composition is well described by a rigid-band model, which breaks down outside this range. Such a breakdown, in the (theoretical) limit of high aluminum concentration, is connected to the appearance of vibrational instabilities and results in important differences between CaAl₂ and MgB₂. Unlike MgB₂, the interlayer band and the out-of-plane phonons play a major role on the stability and superconductivity of CaAlSi and related C₃₂ intermetallic compounds.

Citations

• Generalized Gradient Approximation Made Simple
• Phase Stability in the Systems AeAl2-xMgx (Ae = Ca, Sr, Ba): Electron Concentration and Size Controlled Variations on the Laves Phase Structural Theme
• Ab initio pseudopotentials for electronic structure calculations of poly-atomic systems using density-functional theory
• Electronic and structural properties of superconductingMgB2,CaSi2,and related compounds
• Special points for Brillouin-zone integrations
• Laves-Phase Structural Changes in the System CaAl2-xMgx
• Self-Consistent Equations Including Exchange and Correlation Effects

Cited by

• Electronic Structures of CaAlSi with Different Stacking AlSi Layers by First-Principles Calculations
• NaAlSi: Self-doped semimetallic superconductor with free electrons and covalent holes
• Soft-phonon-driven superconductivity in CaAlSi as seen by inelastic x-ray scattering
• Pressure effects on the superconducting transition innH-CaAlSi