Room-temperature magnetocaloric properties of yLa0.67Ca0.27Sr0.06MnO3/1−yLa0.7Sr0.3Mn0.95Cu0.05O3 composites

In this study, we have characterized the magnetic and magnetocaloric (MC) properties of composites formed by two manganites with appropriate Curie temperatures ( T C ) and acceptable maximum magnetic entropy change ( - Δ S M max ) values. The composites have similar diffraction patterns obtained for the main phases La 0.67 Ca 0.27 Sr 0.06 MnO 3 (LCSM) and La 0.7 Sr 0.3 Mn 0.95 Cu 0.05 O 3 (LSMC) overlapping the diffraction peaks of the perovskite structure. The absence of any diffraction peaks distinct from the main phases in the XRD patterns of the composites indicates that there is no third phase besides the main ones. It is understood from the SEM images that the composites are composed of particles of different shapes and that the interparticle spacing decreases and the grain boundaries become clear, indicating that the interaction between particles becomes stronger with the increase of the y ratio. A gradual transition is seen from the M ( T ) curves, which specify that the composites consist of phases with discrete transition temperatures. The magnetic phase transition of the samples is second order. The - Δ S M max value has been calculated as 3.18, 3.24, and 4.05 J kg −1 K −1 at 5 T magnetic field for the composites 0.25LCSM/0.75LSMC, 0.50LCSM/0.50LSMC, and 0.75LCSM/0.25LSMC, respectively. Since the RCP value of 0.5LCSM/0.5LSMC composite is 301.61 J kg −1 under 5 T, it can be considered as a promising candidate for use in various magnetic cooling technologies at room temperature.