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Abstract
Pressure-induced polymerization of single wall nanotube (SWNT) and fullerite C60 has been studied in situ using shear diamond anvil cell. Bulk modulus of superhard phase of SWNT (SP-SWNT) 465 GPa and ultrahard fullerite (U-C60) 585 GPa were derived from the pressure dependence of the modes in high-energy range of the Raman spectra (i.e. the band 1594cm−1 for SP-SWNT and 1570cm−1 for U-C60). Especially for measurements of bulk modulus of superhard materials new procedure of pressure and stress calibration using stress-induced Raman shift of diamond anvil was elaborated. The bulk moduli of U-C60 and SP-SWNT appropriate to literature data: 540 to 800 GPa for U-C60 depending on the structure and 420 GPa (calculations) for SP-SWNT. It verifies the procedure. Hardness of SP-SWNT (62 to 150 GPa) belongs to the range between cubic BN and diamond; hardness of U-C60 exceeds diamond.