Phase transitions in tungsten monoborides

Three tungsten monoboride phases, including the $I4_1/amd$-$\mathrm{WB}$ and $Cmcm$-$\mathrm{WB}$ phases and the recently predicted stable low-temperature $P\bar{4}2_1m$-$\mathrm{WB}$ phase, have been studied in detail. The crystal structure of stable and metastable tungsten monoborides has been revealed using the $\mathrm{USPEX}$ evolutionary algorithm to predict crystal structures with up to $36$ atoms in the considered unit cell. Possible phase transitions between predicted $\mathrm{WB}$ phases have been thoroughly studied by calculating the pressure–temperature phase diagram indicating the thermodynamic stability ranges. Paths for structural phase transitions have been analyzed using the variable-cell nudged-elastic-band ($\mathrm{VCNEB}$) method. This method allows studying structural changes during phase transitions between monoborides.