Systematic studies of the magnetocaloric properties for the La0.65Ca0.25A0.1MnO3 series (A = alkali metal and alkaline earth metals)

We present results of systematic studies of magnetocaloric effect (MCE) in a series of manganites La0.65Ca0.25A0.1MnO3 with Ca substituted by alkali metal (A = Li, Na, K, Rb, Cs) and alkaline earth metals (A = Mg, Ca, Sr, Ba), i.e. by s-block elements. At first stage we studied La1-xCaxMnO3 for x in the range 0.35-0.4 and we found that the La0.65Ca0.35MnO3 compound was the best starting composition for further fine-tuning the MCE properties by substitution for Ca with A. For each of the La0.65Ca0.25A0.1MnO3 samples an extensive characterization of the physical properties was carried out, including: structural analysis, magnetic susceptibility and magnetization vs applied magnetic field measurements, magnetic phase transition identification by Arrott plots, and finally determination of the isothermal magnetic entropy change - Delta SM. The obtained results indicate a path for searching a compromise composition, i.e. a material exhibiting a reasonable MCE performance at temperatures close to room temperature.