Potential high-Tc superconductivity in ZrB2 polymorph under pressure

Abstract The clear proof of superconductivity in transition-metal diborides was rarely reported. In the current work, the recently developed particle swarm optimization structural search method was utilized to propose three ZrB2 structures, namely, I41/amd-ZrB2, P42/mmc-ZrB2, and P4/nmm-ZrB2. The structural stability of the three novel ZrB2 phases was confirmed on the basis of elastic constant and phonon dispersion calculations. At ambient pressure, the mechanical properties of the I41/amd-ZrB2 and P42/mmc-ZrB2 phases are comparable to those of AlB2–ZrB2. Electron–phonon coupling (EPC) calculations revealed that the P4/nmm-ZrB2 phase is predicted to be a potential high-Tc superconductor with a calculated Tc of 12.7 K at 20 GPa. Moreover, significant pressure-induced EPC enhancement can also be found in the P4/nmm-ZrB2 phase. The maximum EPC constant λ and Tc under 600 GPa are 1.05 and 34.4 K, respectively.