Effect of superconductivity by Nb and V substitution in kagome CaPd₅

Materials featuring kagome lattices have attracted significant research interest due to their unique geometric frustration, which gives rise to rich physical phenomena such as non-trivial topology, spin fluctuations, and superconductivity. In this work, using CaPd₅ as the prototype structure, we discover and systematically investigate a new class of kagome superconductors, CaM_x Pd_5−x (M=Nb and V) alloys. First-principles calculations confirm that these compounds are non-magnetic metals, among which four are dynamically stable: CaNb₅, CaV₅, CaNb₂Pd₃, and CaV₂Pd₃. CaNb₅ is identified as a strong electron–phonon coupling (EPC) superconductor with the highest superconducting transition temperature (T _c) of 10.1 K, which can be further increased to 12.8 K under external pressure. In contrast, CaV₅, CaNb₂Pd₃, and CaV₂Pd₃ exhibit weaker EPC and correspondingly lower T _c values. Furthermore, by applying the method of symmetry indicators, we systematically classify the topological and nodal characteristics of CaNb₅, providing valuable insights for determining its superconducting pairing symmetry. Our findings demonstrate that Nb and V substitution in kagome CaPd₅ provides an effective route for designing a new type of kagome superconductor with relatively high T _c. This study also offers new perspectives on topological superconductivity in kagome systems and establishes a useful guideline for discovering other superconducting materials with unique properties.