Structural and elastic properties of rare-earth nitrides at high pressure

114-118The structural and elastic properties of rare earth nitrides (REN) [RE=Tb, Ce] under high pressure have been investigated by using two body inter ionic potential theory with modified ionic charge (Zme) to include Coulomb screening effect. The present theoretical approach has predicted pressure-volume relationship curves which show that TbN and CeN exhibit a NaCl type structure at an ambient pressure and undergo a structural phase transition from NaCl into CsCl phase at 136 GPa and 88 GPa, respectively. The Second order elastic constants (SOECs), Third elastic constants (TOECs) and second order pressure derivatives for these compounds have also been reported. The variation of elastic constants (C₁₁, C₄₄) with pressure is also presented

Lattice dynamical properties of neptunium chalcogenides

98-101The phonon calculations of neptunium chalcogenides (NpX; X = S, Se, Te) based on breathing shell model (BSM) which includes breathing motion of electron of the Np-atoms due to f-d hybridization, have been performed. The significance of this approach in predicting the phonon properties of NpX compounds has been discussed and the role of f-electron has been examined. The model predicts that the short range breathing phenomenon plays a dominant role in the phonon properties. The specific heat for these compounds has been reported