We experimentally study the structure, magnetic and magnetocaloric effect of Pr$_{0.5}$Sr${0.5}$Mn$_{1–x}$Co$_x$O$_3$ (0.00${\leq}$x${\leq}$ 0.08) with the substitution of Co. The results of the refined XRD data show that all the samples have a tetragonal structure with the I4/mcm space group. The small amount of Co substitution does not change the structure of the materials. However, the magnetization data indicate that the charge-ordered antiferromagnetic state vanishes with a small amount of Co substitution. The Curie temperature of samples can be effectively tuned with the substitution and it decreases from 270 to 175 K. With a magnetic field change of 15 kOe, the maximum magnetic entropy change (|${\varDelta}$$S$$_M$|max)of the samples increases to 1.21 J kg$^{-1}$ K$^{-1}$ at $T$$_C$ = 255 K for x = 0.02, and then decrease monotonically. All samples undergo second-order phase transition. The wide operating range makes our compounds as good refrigeration candidates.

We studied the effect of Eu$^{3+}$ substitution on the structural, magnetic and magnetocaloric properties of La$_{0.7-x}$Eu$_x$Ba$_{0.3}$MnO$_3$ (x = 0, 0.02, 0.04, 0.06 and 0.08) (LEBMO). The material is prepared by solid-state sintering method. X-ray diffraction and structural refinement parameters indicate that all the synthesized samples have single-phase hexagonal structure. Magnetic measurements indicate that Curie temperature ($T_C$) of the samples decrease with increasing Eu$^{3+}$ content, because of the weakening of double exchange interaction. All samples present a second-order ferromagnetic to paramagnetic phase transition. Magnetic entropy change (${\Delta}S_M$) of the samples increases as the Eu$^{3+}$ content enhance. When x = 0.08, the $T_C$ of the sample is 258.6 K and the maximum value of ${\Delta}S_M$ reaches 3.27 J kg$^{-1}$ K$^{-1}$ at 5 T of a magnetic field. These results indicate that the material can be used as an ideal working material for the normal temperature magnetic refrigeration.