Motivated by the discovery of superconductivity in bilayer La$_3$Ni$_2$O$_7$ at 80 K and the increased superconducting transition temperature, $T_text{c}$, up to 92 K in single crystals of La$_2$SmNi$_2$O$_7$ under pressure, we systematically study the effect of Sm doping on the superconductivity and structure of La$_{3-x}$Sm$_x$Ni$_2$O$_7$ (0 $leq$ x $leq$ 1.5) under pressure. Experimental investigations in polycrystalline samples reveal that Sm doping monotonically decreases the lattice constants $c$ and $a$, thereby enhancing crystal structure distortion and leading to an evolution of the metallic ground state in La$_3$Ni$_2$O$_7$ to an insulating state in La$_{1.5}$Sm$_{1.5}$Ni$_2$O$_7$. The maximum onset $T_text{c}$ in compounds $x=0.9$ and 1.5 is 89 K, while the pressure that drives the emergence of superconductivity is higher for higher doping levels. The results suggest that the enhancement of $T_text{c}$ in La$_{3-x}$Sm$_x$Ni$_2$O$_7$ is mainly affected by the compressed $c$ lattice before saturation, and the structure transition is critical for the emergence of superconductivity. Our experimental results provide insight into the influence of elemental substitution on nickelate superconductors, offering a means to increase the transition temperature further.
受双层La $_3$ Ni $_2$ O $_7$在80 K时超导性的发现和La $_2$ SmNi $_2$ O $_7$单晶在压力下超导转变温度$T_text{c}$提高到92 K的启发，我们系统地研究了压力下Sm掺杂对La $_{3-x}$ Sm $_x$ Ni $_2$ O $_7$ （0 $leq$ x $leq$ 1.5）超导性和结构的影响。在多晶样品中的实验研究表明，Sm掺杂单调地降低了晶格常数$c$和$a$，从而增强了晶体结构的变形，导致La $_3$ Ni $_2$ O $_7$的金属基态演变为La $_{1.5}$ Sm $_{1.5}$ Ni $_2$ O $_7$的绝缘态。化合物$x=0.9$和1.5的最大起始点$T_text{c}$为89 K，而随着掺杂水平的提高，驱动超导性出现的压力也越大。结果表明，在La $_{3-x}$ Sm $_x$ Ni $_2$ O $_7$中$T_text{c}$的增强主要受饱和前压缩的$c$晶格的影响，结构转变是超导性产生的关键。我们的实验结果为元素取代对镍酸盐超导体的影响提供了深入的见解，为进一步提高转变温度提供了一种方法。
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