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Raman spectrum and lattice parameters of MgB 2 as a function of pressure

2001; American Physical Society; Volume: 64; Issue: 10 Linguagem: Inglês

10.1103/physrevb.64.100509

1095-3795

Alexander F. Goncharov, Viktor V. Struzhkin, Eugene Gregoryanz, Jingzhú Hu, Russell J. Hemley, Ho‐kwang Mao, G. Lapertot, S.L. Bud’ko, P. C. Canfield,

Thermal Expansion and Ionic Conductivity

We report Raman spectra and synchrotron x-ray diffraction measurements of lattice parameters of polycrystalline MgB2 under hydrostatic pressure conditions up to 15 GPa. An anomalously broadened Raman band at 620 cm-1 is observed that exhibits a large linear pressure shift of its frequency. The large mode damping and Gruneisen parameter indicate a highly anharmonic nature of the mode, broadly consistent with theoretical predictions for the E2g in-plane boron stretching mode. The results obtained may provide additional constraints on the electron-phonon coupling in the system.