The electronic, elastic, and structural properties of Ti–Pd intermetallics and associated hydrides from first principles calculations

First-principles studies of structural stabilities and enthalpies of formation of refractory intermetallics: TM and TM3 (T = Ti, Zr, Hf; M = Ru, Rh, Pd, Os, Ir, Pt)

“…Our calculation, however, found that the ground state of TiPd is actually in the B19 0 structure [82], which has energy 1.0, 1.4, 8.0 and 13.3 kJ (mol of atoms) À1 lower than that of the B19, L1 0 , B2, and B33 structures, respectively. We found that the B2 phase is mechanically unstable against the shear deformation due to a negative shear modulus of C 11 eC 12 ¼ À18.2 GPa.…”

“…For TiPd, the high temperature austenite phase is a cubic B2 structure [30,44,82] and the ambient temperature martensite phase has been reported as an orthorhombic B19 phase [44,46,54]. Our calculation, however, found that the ground state of TiPd is actually in the B19 0 structure [82], which has energy 1.0, 1.4, 8.0 and 13.3 kJ (mol of atoms) À1 lower than that of the B19, L1 0 , B2, and B33 structures, respectively.…”

“…Experiments have found that the off-stoichiometric composition of Ti 1.3 Ir 0.7 has a high-temperature B2 phase and a lowtemperature L1 0 structure [42,51,82]. However, there is some conflicting experimental information on the structure of TiIr at room temperatures: Schubert et al [61] assigned TiIr to an orthorhombic structure, but Eremenko and Shtepa [65] found that TiIr has a monoclinic structure.…”

Hydrogenation properties of shape memory Ti(Ni,Pd) compounds

“…but at higher hydrogen content a orthorhombically distorted hydride is formed. In contrast, owing to electronic effects, TiPd 2 compound does not absorb hydrogen as proved by Chen et al from DFT calculations [37]. These authors have also shown that the stability of TiePd compounds increases as Ti 2 Pd < TiPd < TiPd 2 .…”

“…On the other hand, for TiPd, no hydrogenation data exist which may be related to a low reactivity between this compound and hydrogen. Nevertheless, previous studies on the hydrogenation properties of Ti 2 Pd and TiPd 2 compounds have been reported [36,37]. Ti 2 Pd can absorb hydrogen up to 2 H/f.u.…”