Structure and bonding in YH as derived from elastic and inelastic light scattering

Distortion of the fcc lattice in superstoichiometric -YH2+δ and cubic YH3−η thin films

“…For hcp YH 3 we use the P6 3 cm structure. This is the most favored structure from Raman spectroscopy [11], [12] and neutron diffraction measurements [13], which also agrees with theory [14]. In agreement with neutron diffraction [3] and theory [5] we assume for the superstoichiometric YH 2+δ the I4/mmm crystal structure.…”

The nature of deuterium arrangements in YD3 and other rare-earth trideuterides

“…Different spectroscopic probes such as neutron vibrational spectroscopy (NVS) [18,21,22,[32][33][34], Raman spectroscopy [35,36], infrared (IR) spectroscopy [35][36][37], and nuclear magnetic resonance (NMR) [38][39][40] have provided further clues concerning the local structural symmetry. Initial scrutiny of NV spectra for YH 3 and related hexagonal rare-earth trihydrides [19,22,32] led to the suggestion that the hydrogen vibrational lineshapes best reflected a local P 3 3c1 symmetry, although a more rigorous modeling of the data was needed to confirm this.…”

New insights from Raman and IR spectroscopy into the metal-insulator transition of YHx switchable mirrors

“…Fig. 6 displays reflectivity spectra in the IR for various temperatures from 20 to 280 K. One sees four lines which have been assigned previously to the excitation of phonons [5]. However, the present systematic study reveals that the line near 730 cm −1 shows a markedly different intensity behavior than the three other lines, pointing to a different origin, although Raman measurements under an angle of incidence of 45 • indicate at this energy the existence of an E 1 phonon [4] which should also be IR active.…”

“…A major reason is that before switchable mirrors had been discovered in 1996 [2], powerful techniques to study the electronic structures of solids, like optical and photoelectron spectroscopies, could not be applied effectively. Since then, a growing number of experiments [3][4][5][6][7][8] points to a correlated description of the electronic structure of the prototype YH x system, in agreement with some of the theoretical models put forward recently for YH x or LaH x [9,10]. This contradicts earlier attempts to describe these materials with simple oneelectron band structure calculations [11][12][13] and conflicts with the idea that hydrogen enters into the metal lattice as proton.…”