Highpressure MgScH phase diagram and its superconductivity from firstprinciples calculations
Abstract
In this work, global search for crystal structures of ternary MgScH hydrides (Mg$_x$Sc$_y$H$_z$) under high pressure ($100 \le P \le 200$ GPa) were performed using the evolutionary algorithm and firstprinciples calculations. Based on them, we computed the thermodynamic convex hull and pressuredependent phase diagram of Mg$_x$Sc$_y$H$_z$ for $z/(x+y) < 4$. We have identified the stable crystal structures of four thermodynamically stable compounds with the higher hydrogen content, i.e., $R\bar{3}m$MgScH$_{6}$, $C2/m$Mg$_{2}$ScH$_{10}$, $Immm$MgSc$_{2}$H$_{9}$ and $Pm\bar{3}m$Mg(ScH$_{4}$)$_{3}$. Their superconducting transition temperatures were computationally predicted by the McMillanAllenDynes formula combined with firstprinciples phonon calculations. They were found to exhibit superconductivity; among them, $R\bar{3}m$MgScH$_{6}$ was predicted to have the highest $T_{c}$ (i.e. 23.34 K) at 200 GPa.
 Publication:

arXiv eprints
 Pub Date:
 September 2021
 arXiv:
 arXiv:2109.07051
 Bibcode:
 2021arXiv210907051S
 Keywords:

 Condensed Matter  Superconductivity;
 Condensed Matter  Materials Science
 EPrint:
 7 pages, 5 figures, 1 Supplemental Material