Neutron spectroscopy of TiH_0.74after high pressure treatment

Abstract

Hi& molution neutmn scattering studies of vibrationel spectra (2-800 meV) were carried out on the e-, 6'and 6-phof titanium hydride, obtained after high pressure treatment. The observed splitting of the fundamental optic peak in the &-phase spectrum can be explained by a strong H-H interaction along the D axis. Well pronounced features are seen on the low energy side of the tw-and three phonon optic bands. Thex are assigned to bound bi-and tri-phonon excitations. This is the first observation of biand tri-phonons in metal hydrides.

First-principles investigations of isotope effects in thermodynamic properties of TiX2 (X=H, D, and T) system

“…Generally, we can use the concept of phonon to describe thermal vibrations and to determine thermal properties in crystals and in particular their specific heat, thermal expansion coefficients and so on. In this paper we address its application to the thermal properties of Ti-H (Ti-D or Ti-T) as H (D or T) storage materials [17][18][19][20][21][22] since for them many experimental works have been done. Some researchers [18,19] have manifested that hydrogen (deuterium or tritium) mainly occupies tetrahedral interstitial sites of FCC TiH x (TiD x or TiT x ) with the H (D or T) content x (for TiH x , x = 51.2-66.7 at.%).…”

“…Some researchers [18,19] have manifested that hydrogen (deuterium or tritium) mainly occupies tetrahedral interstitial sites of FCC TiH x (TiD x or TiT x ) with the H (D or T) content x (for TiH x , x = 51.2-66.7 at.%). Kolesnikov et al [20] have measured the vibrational spectra of TiH 0.74 treated by high-pressure using a high-resolution neutron scattering method. Recently, Setoyama et al [21] have performed a series of investigations on the mechanical and thermal properties of titanium hydride with an ultrasonic pulse-echo method and other experimental techniques.…”

On the Dynamics and Site Occupation of D Atoms in ? and ? Deuterides of Zr

“…Nevertheless, its clear meaning requires further experimental and theoretical studies. For the Zr±H(D) system evidence for a complex H(D) behaviour similar to that observed for the Ti±H(D) system (in terms of a dual occupancy of both T and O sites by D [15] or H [16] atoms in Ti lattice) was not revealed so far.…”

Dynamical structure factor of a nonlinear Klein-Gordon lattice

“…The sum over the subscript j in Eq. (5) gives zero for all q, aside from the wave vectors that match the momentum conservation [(q − k).v] = 0. This condition, as well as the conservation of the energy are supposed to be satisfied for a given state ψ(k).…”

“…Three noteworthy resonances emerge with same order of magnitude. These three resonances correspond to the eigen-energies of the nonlinear phonon states, i.e., the phonons, biphonons and triphonons.The binding energy of the biphonon, evaluated at the center of the Brillouin zone (BZ) is around a few percent of the fundamental phonon excitation, as measured in different metal hydrides5,6 . Several model parameters have been tested and lead to qualitatively similar results.…”