Bulk NiTe₂ is a type-II Dirac semimetal with non-trivial Berry phases associated with the Dirac fermions. Theory suggests that monolayer NiTe₂ is a two-gap superconductor, whereas experimental investigation of bulk NiTe_1.98 for pressures (P) up to 71.2 GPa do not reveal any superconductivity. Here we report experimental evidences for pressure-induced two-phase superconductivity as well as mixed structures of NiTe₂ and NiTe in Te-deficient NiTe_2-x (x = 0.38 ± 0.09) single crystals. Hole-dominant multi-band superconductivity with the $\text{P}\overline{3}m1$ hexagonal-symmetry structure of NiTe₂ appears at P ≥ 0.5 GPa, whereas electron-dominant single-band superconductivity with the P2/m monoclinic-symmetry structure of NiTe emerges at 14.5 GPa < P < 18.4 GPa. The coexistence of hexagonal and monoclinic structures and two-phase superconductivity is accompanied by a zero Hall coefficient up to ∼ 40 GPa, and the second superconducting phase prevails above 40 GPa, reaching a maximum T_c = 7.8 K and persisting up to 52.8 GPa. Our findings suggest the critical role of Te-vacancies in the occurrence of superconductivity and potentially nontrivial topological properties in NiTe_2-x.

块状NiTe ₂是II型Dirac半金属，具有与Dirac费米子相关的非平凡Berry相。理论表明，单层NiTe ₂是两间隙超导体，而对体积NiTe _1.98进行的高达71.2 GPa的压力（P）的实验研究没有发现任何超导性。在这里，我们报告了在Te缺陷型NiTe _{2- x}（x  = 0.38±0.09）单晶中压力引起的两相超导以及NiTe ₂和NiTe混合结构的实验证据。空穴主导的多带超导与$\text{P}\overline{3}米\mathrm{1个}$NITE的六边形对称性结构_2只在出现P  ≥为0.5GPa，而电子显性单频段超导与P2 / m的NITE的单斜晶对称结构出现在14.5 GPA <  P  <18.4 GPA。六方结构和单斜晶结构以及两相超导性共存，零霍尔系数高达40 GPa，第二超导相占40 GPa以上，最大T _c  = 7.8 K，持续高达52.8 GPa。我们的发现表明，Te空位在NiTe _{2- x}中超导性的发生和潜在的不重要的拓扑性质中起着至关重要的作用。