We have studied single crystals of C 70 by Raman scattering and photoluminescence in the pressure range from 0 to 31.1 GPa. The Raman spectrum at 31.1 GPa shows only a broad band similar to that of the amorphous carbon without any trace of the Raman lines of C 70 . After releasing the pressure from 31.1 GPa, the Raman and the photoluminescence spectra of the recovered sample are that of the starting C 70 crystal. These results indicate that the C 70 molecules are stable upto 31.1 GPa and the amorphous carbon high pressure phase is reversible, in sharp contrast to the results on solid C 60 . A qualitative explaination is suggested in terms of inter-versus intra-molecular
High pressure Raman and angle dispersive X-ray diffraction (ADXRD) measurements on the metallic hexaboride LaB 6 have been carried out upto the pressures of about 20 GPa. The subtle phase transition around 10 GPa indicated in Raman measurements is confirmed by ADXRD experiments to be a structural change from cubic to orthorhombic phase. Ab-initio electronic band structure calculations using full potential linear augmented plane wave method carried out as a function of pressure show that this transition is driven by the interception of Fermi level by electronic band minimum around the transition pressure.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.