The Ruddlesden–Popper (R–P) bilayer nickelate, La₃Ni₂O₇, was recently found to show signatures of high-temperature superconductivity (HTSC) at pressures above 14 GPa (ref. ¹). Subsequent investigations achieved zero resistance in single-crystalline and polycrystalline samples under hydrostatic pressure conditions^2,3,4. Yet, obvious diamagnetic signals, the other hallmark of superconductors, are still lacking owing to the filamentary nature with low superconducting volume fraction^2,4,5. The presence of a new 1313 polymorph and competing R–P phases obscured proper identification of the phase for HTSC^6,7,8,9. Thus, achieving bulk HTSC and identifying the phase at play are the most prominent tasks. Here we address these issues in the praseodymium (Pr)-doped La₂PrNi₂O₇ polycrystalline samples. We find that substitutions of Pr for La effectively inhibit the intergrowth of different R–P phases, resulting in a nearly pure bilayer structure. For La₂PrNi₂O₇, pressure-induced orthorhombic to tetragonal structural transition takes place at P_c ≈ 11 GPa, above which HTSC emerges gradually on further compression. The superconducting transition temperatures at 18–20 GPa reach \({T}_{{\rm{c}}}^{{\rm{onset}}}=82.5\,{\rm{K}}\) and \({T}_{{\rm{c}}}^{{\rm{zero}}}=60\,{\rm{K}}\), which are the highest values, to our knowledge, among known nickelate superconductors. Importantly, bulk HTSC was testified by detecting clear diamagnetic signals below about 75 K with appreciable superconducting shielding volume fractions at a pressure of above 15 GPa. Our results not only resolve the existing controversies but also provide directions for exploring bulk HTSC in the bilayer nickelates.

最近发现 Ruddlesden-Popper （R-P） 双层镍酸盐 La₃Ni₂O₇ 在高于 14 GPa 的压力下显示出高温超导 （HTSC） 的特征（参考文献 ¹）。随后的研究在静水压力条件下实现了单晶和多晶样品的零电阻^2,3,4。然而，由于超导体积分数低的丝状性质^{2,4,5，仍然}缺乏明显的抗磁信号，这是超导体的另一个标志。新的 1313 多晶型物和竞争性 R-P 相的存在掩盖了对 HTSC^6,7,8,9 相的正确鉴定。因此，实现批量 HTSC 和确定起作用的阶段是最突出的任务。在这里，我们解决了镨 （Pr） 掺杂 La₂PrNi₂O₇ 多晶样品中的这些问题。我们发现 Pr 取代 La 有效抑制了不同 R-P 相的共生，从而产生近乎纯的双层结构。对于 La₂PrNi₂O₇，压力诱导的正交到四方结构转变发生在 P_c ≈ 11 GPa，超过该转变后 HTSC 在进一步压缩时逐渐出现。18-20 GPa的超导转变温度达到\（{T}_{{\rm{c}}}^{{\rm{onset}}}=82.5\，{\rm{K}}\）和\（{T}_{{\rm{c}}}^{{\rm{zero}}}=60\，{\rm{K}}\），据我们所知，这是已知的镍酸盐超导体中的最高值。重要的是，通过在高于 15 GPa 的压力下检测到低于约 75 K 的清晰抗磁信号和明显的超导屏蔽体积分数来证明体 HTSC。 我们的结果不仅解决了现有的争议，而且为探索双层镍酸盐中的体 HTSC 提供了方向。