Enhanced Superconductivity in Close Proximity to the Structural Phase Transition of Sr1−xBaxNi2P2

The structural evolution and superconductivity of a 122-type solid solution Sr1−xBaxNi2P2 were studied. We found that an orthorhombic–tetragonal structural phase transition takes place at x = 0.5, and is characterized by the P–P dimers breaking. The superconducting transition temperature exhibited its highest value of 2.85 K at x = 0.4.