Effect of calcium doping on structural, magnetic and magneto-caloric properties of La0.55CaxSr0.45-xMnO3 manganites

•Polycrystalline manganite La0.55CaxSr0.45-xMnO3 (x = 0.00, 0.05, 0.1 and 0.25) have been prepared by conventional solid-state reaction technique.•Room temperature XRD measurements disclose rhombohedral structure for all the samples.•With increasing Ca content, lattice parameters are found to be decreased.•Curie temperature decreases toward the room temperature with increase in Ca content.•Maximum value of (-ΔSm) and RCP reduces with the introduction of Ca content while increase in Ca content tunes the Curie temperature near the room temperature.