Prediction of high- Tc superconductivity in ternary lanthanum borohydrides

Abstract

The study of superconductivity in compressed hydrides is of great interest due to measurements of high critical temperatures (T c ) in the vicinity of room temperature, beginning with the observations of LaH 10 at 170-190 GPa. However, the pressures required for synthesis of these high-T c superconducting hydrides currently remain extremely high. Here we show the investigation of crystal structures and superconductivity in the La-B-H system under pressure with particle-swarm intelligence structure-searches methods in combination with first-principles calculations. Structures with seven stoichiometries, LaBH, LaBH 4 , LaBH 6 , LaBH 7 , LaBH 8 , La(BH) 3 , and La(BH 4 ) 3 were predicted to become stable under pressure. Remarkably, the hydrogen atoms in LaBH 8 were found to bond with B atoms in a manner that is similar to that in H 3 S. Lattice dynamics calculations indicate that LaBH 7 and LaBH 8 become dynamically stable at pressures as low as 109 and 48 GPa, respectively. Moreover, the two phases were predicted to be superconducting with a critical temperature T c of 93 K and 156 K at 110 GPa and 55 GPa, respectively (μ * = 0.1). The present results provide guidance for future experiments targeting hydride superconductors with both low synthesis pressures and high T c .

Hot Hydride Superconductivity Above 550 K

“…Note: While in preparation, we have become aware of four publications that attempt to explain our finding (Ge et al, 2021;Guan et al, 2021;Liang et al, 2021;Di Cataldo et al, 2022).…”

Emergent superconductivity in K2ReH9 under pressure

“…59 As far as we know, P 6 3 / mcm K 2 ReH 9 becomes the highest- T c conventional superconductor among the pressurized ambient-pressure compounds, comparable to the predicted 126–138 K of LaBH 8 at 50 GPa, a famous low-pressure superconducting hydride. 63 By inspecting the change of λ and ω log , two main parameters for determining T c value, it is apparent that λ plays a dominant role in the T c evolution with pressure while ω log presents an opposite trend. Further, the elevated EPC with lowering pressure can be attributed to synergetic promotion of electron and phonon evolution.…”

Potential high-$T_{c}$ superconductivity in YCeH$_{20}$ and LaCeH$_{20}$ under pressure

“…But then multi-component hydrides contain more combinations of elements, they are more promising in the search for high(room)-temperature superconductivity. [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] For example, magnesium hydride can dissociate the H 2 molecule into atomic H by lithium doping, thus increasing its electron concentration at the Fermi level (E F ), enabling it to reach a T c value of 473 K at 250 GPa. [47] Furthermore, recent research has revealed that a small amount of carbon doping in H 3 S can result in room superconductivity (T c = 287.7 ± 1.2 K at 267 ± 10 GPa).…”