Pressure-Induced Superconductivity in the Thermoelectric Semiconductor Mg 3 Sb 2

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The intrinsic electronic structures of narrow bandgap thermoelectric (TE) materials serve as a platform for the investigation of coupling effects of quasi-particles under high pressure, enabling the exploration of emerging electronic and phonon transport, superconductivity, and topological transitions. Here, we report the discovery of pressure-induced superconductivity in the TE semiconductor Mg 3 Sb 2 . Upon increased pressure, metallization occurs at ∼8.7 GPa, followed by a superconducting transition concomitant with a carrier-type crossover from p - to n -type. This phenomenon arises from a pressure-induced structural phase transition from the semiconducting P 3̅ m 1 to the metallic C 2/ m -I phase. The superconducting critical temperature ( T c ) exhibits a dome-shaped pressure dependence, peaking at 3.3 K at 12.6 GPa. Combined theoretical calculations, high-pressure Raman spectroscopy, and X-ray diffraction (XRD) measurements reveal an additional structural transition above ∼20 GPa, yielding a distinct C 2/ m -II phase. Our findings establish the high-pressure phase diagram of Mg 3 Sb 2, elucidate its pressure-dependent electronic properties, and provide valuable insights for future investigations of TE materials under high pressure.

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