Ab-initio studies of some rare-earth borides: CeB2, PrB2, NdB2, and PmB2

The structural, mechanical and thermal properties of CeB2, PrB2, NdB2, and PmB2 compounds in hexagonal AlB2-type (P6/mmm) and ReB2-type structures (P6(3)/mmc) are investigated using density functional theory. The results indicate that those compounds with hexagonal AlB2 structure are the most stable among the considered structures. The mechanical properties are calculated according to the elastic constants by means of the Voigt-Reuss-Hill averaging scheme. The temperature dependence of various quantities such bulk modulus, Debye temperature, thermal expansion, heat capacity, and Gruneisen parameter have been analyzed using the quasi-harmonic Debye model