Crystal structure and lattice dynamics of AlB2 under pressure and implications for MgB2

Abstract

The effect of high pressures to 40 GPa on the crystal structure and lattice dynamics of AlB2 was studied by synchrotron x-ray powder diffraction, Raman spectroscopy, and first-principles calculations. There are no indications for a pressure-induced structural phase transition. The Raman spectra of the metallic sample exhibit a well-defined peak near 980 cm^{-1} at 0 GPa which can be attributed to the Raman-active E_{2g} zone-center phonon. Al deficiency of ~11% in AlB2, as indicated by the x-ray data, changes qualitatively the electronic structure, and there are indications that it may have a sizable effect on the pressure dependence of the E_{2g} phonon frequency. Similar changes of the pressure dependence of phonon frequencies, caused by non-stoichiometry, are proposed as an explanation for the unusually large variation of the pressure dependence of T_c for different samples of MgB2.

9 pages, 7 EPS figures, revtex4

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Cited by in corpus (8)

• Elastic properties of mono- and polycrystalline hexagonal AlB2-like diborides of s, p and d metals from first-principles calculations
• Role of charge doping and lattice distortions in codoped Mg_{1-x}(AlLi)_{x}B_2 compounds
• Electron-phonon coupling in a honeycomb borophene grown on Al(111) surface
• Superconductivity of Various Borides: The Role of Stretched c- Parameter
• Possible superlattice formation in high-temperature treated carbonaceous MgB2 at elevated pressure
• Atomic models of non-stoichiometric layered diborides M${}_{1-x}$B${}_2$ (M = Mg, Al, Zr and Nb) from first principles
• Natural hyperbolicity in the layered hexagonal crystal structure
• Metal deficient AlB${}_2$-type (Ti${}_{0.2}$Zr${}_{0.2}$Hf${}_{0.2}$Nb${}_{0.2}$Ta${}_{0.2}$)${}_{1-\delta }$B${}_2$ high-entropy diborides with high hardness