Nano crystalline La_0.8Ag_0.2MnO₃ perovskite compound was prepared using sol–gel method. The synthesized nano compound was characterized using X-ray Diffraction (XRD) and High Resolution - Transmission Electron Microscope (HR–TEM). The magnetic and magnetocaloric properties were studied in a broad temperature range, and confirmed the presence of ferromagnetic–paramagnetic (FM–PM) transition around Curie temperature (T_C = 306 K). We reported a maximum magnetic entropy change |ΔS_M|_max = 0.96 J/kg.K with relative cooling power (RCP) = 39.98 J/kg at magnetic field 2 T. Such results could be a significant practical application in magnetic refrigeration.

The observed magnetic phase transition in the sample was testified a second order. The critical exponent analysis which define the magnetic transition revealed values 0.4025 for β, 3.33 for δ and 0.93 for γ. These values are closely related to those obtained by the mean field model. The second order magnetic phase transition is further confirmed by constructing a universal curve for variation of |ΔS_M|/|ΔS_max| vs rescaled temperature (θ) for various magnetic field values.