Dynamical stability of the lanthanum dihydride under high pressure: A density functional lattice dynamics approach

Gupta, Sanjeev K.; Jha, Prafulla K.

doi:10.1016/j.ijhydene.2013.01.179

Cited by 20 publications

(7 citation statements)

References 49 publications

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“…The study of the superconductivity of hydrides under high pressure has attracted more and more research interest. Many hydrides, such as H 2 S [1], GaH 3 [2], SnH 4 [3,4], SiH 4 [5][6][7] and rare-earth metal hydrides LaH 2 [8,9], ScH 3 [10] and YH 3 , have been investigated for superconductivity [11]. In particular, several hydrogen-rich compounds at high pressures, e.g.…”

Section: Introductionmentioning

confidence: 99%

High-pressure structures of yttrium hydrides

Liu¹,

Sun²,

Wang³

et al. 2017

J. Phys.: Condens. Matter

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In this work, the crystal structures of YH and YH at high pressure (100-250 GPa) have been explored using a genetic algorithm combined with first-principles calculations. New structures of YH with space group symmetries of P21/m and I4/mmm were predicted. The electronic structures and the phonon dispersion properties of various YH and YH structures at different temperatures and pressures were investigated. Among YH phases, the P21/m structure of YH was found to have a relatively high superconducting transformation temperature T of 19 K at 120 GPa, which is reduced to 9 K at 200 GPa. Other YH structures have much lower T s. Compared with YH, the T of the YH compound is much higher, i.e. 94 K at 120 GPa and 55 K at 200 GPa.

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Section: Introductionmentioning

confidence: 99%

High-pressure structures of yttrium hydrides

Liu¹,

Sun²,

Wang³

et al. 2017

J. Phys.: Condens. Matter

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“…Interestingly, the volume of the I 4/ mmm phase decreases with pressure by 0.25 Å 3 /GPa, whereas the volume of the C 2/ c phase decreases slowly with pressure by 0.05 Å 3 /GPa. These results indicate that ThH 2 becomes difficult to compress under pressure, which is a typical behavior in metal hydrides. , Figure b shows the lattice parameters of the two phases for ThH 2 . The lattice parameter a of the I 4/ mmm phase decreases much slowly than the lattice parameter c , resulting in that they cross over at round 25 GPa.…”

Section: Resultsmentioning

confidence: 87%

“…These results indicate that ThH 2 becomes difficult to compress under pressure, which is a typical behavior in metal hydrides. 56,58 Figure 5b shows the lattice parameters of the two phases for ThH 2 . The lattice parameter a of the I4/mmm phase decreases much slowly than the lattice parameter c, resulting in that they cross over at round 25 GPa.…”

Section: Resultsmentioning

confidence: 99%

Zero-Point Effects on Phase Transitions of Thorium Dihydride under High Pressure

et al. 2015

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The crystalline structures of thorium dihydride, ThH 2 , under pressure are investigated by using an unbiased structure searching method coupled with ab initio calculations. Three low-enthalpy phases are found as the thermodynamic ground states of ThH 2 up to 200 GPa, including an experimentally observed I4/mmm phase and two newly predicted monoclinic phases (C2/m and C/2c phase). ThH 2 is predicted to undergo I4/mmm → C2/m → C/2c phase transitions without zero-point (ZP) effects, whereas it directly transforms from the I4/mmm phase to the C2/c phase with ZP effects. Phonon calculations show that these competitive phases are thermodynamically stable. There is a strengthening of the metallic characters of the chemical bonding with increased pressure. Our results highlight the role of ZP effects in the high-pressure behaviors of metal hydrides and provide insight into further studies of other compounds containing light elements under pressure.

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“…This result indicates that the chemical bonds between Ac and H atom exhibit some covalent characters under pressure. To some degree, AceH interaction in AcH 2 characterizes a mixture of ionic and covalent components, just as the inherent bonding nature in most hydrides [55,56]. With increasing pressure, the covalent characters are strengthened, which facilitates the hydrogen storage application [10].…”

Section: Resultsmentioning

confidence: 99%