Hexagonal to cubic phase transition in YH3 under high pressure

Consecutive Peierls distortions and high-pressure phase transitions inYH3

“…Once the C2 / m structure completely changes to fcc at 38 GPa, the band gap closes completely and YH 3 becomes metallic. The pressure-dependent insulating properties of the C2 / m structure agree well with the experimental observation [4][5][6][7] for the intermediate phase in this pressure range.…”

“…A series of studies have characterized the highpressure phase transitions for YH 3 up to 40 GPa. [2][3][4][5][6][7][8] At ambient pressure, YH 3 forms a distorted hcp form identified with space group P3c1 by neutron diffraction. [9][10][11] There are two other suggested possible structures 12,13 that are almost energetically degenerate but not in agreement with recent neutron-diffraction data.…”

“…14,15 The ambient-pressure structure is shown to transform to the fcc structure over a large pressure span ranging from about 9 to 24 GPa. [4][5][6][7][8] There are experimental evidences showing an intermediate phase in this transition but the precise characterization of this structure is under debate. 4,7 During the phase transition, the band gap in YH 3 starts to narrow in the intermediate phase and closes once the structure completely transforms into fcc.…”

“…[4][5][6][7][8] There are experimental evidences showing an intermediate phase in this transition but the precise characterization of this structure is under debate. 4,7 During the phase transition, the band gap in YH 3 starts to narrow in the intermediate phase and closes once the structure completely transforms into fcc. The pressure of metallization for YH 3 is the lowest observed pressure for metallization of hydrogen-rich compounds to date.…”

Electrical Properties of YH3under High Pressure

“…1,2) Recently, an abrupt closure of the optical gap at 23 GPa was reported by Ohmura et al; the transmission intensity became zero in the infrared region. 3) They claimed that this might indicate that an insulator-tometal transition was induced by the overlap of the electron orbitals of neighboring hydrogen atoms.…”