Compressibility, microcalorimetry, elastic properties and EELS of rhenium borides
Ávalos Borja, Miguel
Silva Pereyra, Héctor Gabriel
"Based on synchrotron X-ray diffraction on phase-pure samples, we revised the bulk moduli of the rhenium borides Re7B3 (B-0 (Re7B3) = 391(5) GPa) and orthorhombic Re3B (B-0 (orthorhombic Re3B) = 393(4) GPa) and determined the bulk modulus of monoclinic Re3B (B-0 (monoclinic Re3B) = 390(3) GPa). These results agree well with the DFT calculations on the elastic properties. Microcalorimetry was employed to obtain thermodynamic data for Re7B3 and orthorhombic Re3B and we determined C-P,(298) (Re7B3) = 210(4) J/mol, Delta H-2(98)0 (Re7B3) = 40558(400) J/mol, S-298(0) (Re7B3) = 267(2) J/mol K and theta(D)(,)(298) (Re7B3) = 320(2) K, as well as C-p,(298) (Re3B)= 86(1) J/mol, Delta H-2(98)0 (Re3B) = 16950(170) J/mol, S-2(98)0 (Re3B) 112(1) J/mol K and theta(D,)(298) (Re3B) = 329(3) K. Hardness measurements were performed for Re7B3, which gave a Vickers hardness H-V(5 kgf) = 14.5(4) GPa and H-V(10 kgf) = 14.1(3) GPa. Electron energy loss spectroscopy (EELS) was performed on orthorhombic Re3B and ReB2, and the experimental spectra are well reproduced by theory in terms of their absorption edges."
KeywordsTransition metal borides
Density functional theory