Magneto-functionalities of La1-xAxMnO3 (A = K; Ba) synthesized by flash combustion method

Abstract Due to their relatively large magnetocaloric effect, Ba and K doped LaMnO3 can be used in magnetic cooling systems. In this study, La1-xBaxMnO3 (x = 0.1; 0.2) and La0.9K0.1MnO3 powders were synthesized by the flash combustion method using glycine as a fuel and chelating agent. A subsequent calcination at 1000 °C was performed. Different characterization tools were used to carry out a detailed study of the structural, morphological, thermal, electrical, and magnetic behaviors of the doped materials. The structure of un-doped and doped samples was examined by X-ray Diffraction. According to magnetic data, La0.9K0.1MnO3 exhibits a ferromagnetic-paramagnetic phase transition at 271 K and a magnetic entropy variation under a magnetic induction of 4 T /ΔSM/ = 5.33 J kg−1K−1. On the other hand, the Curie temperature of La1-xBaxMnO3 increases with the Ba content from 157 K for x = 0.1 to 200 K for x = 0.2, whereas /ΔSM/ decreases from 2.56 J kg−1K−1 to 2.07 J kg−1K−1, respectively. Accordingly, it has been proven that the highest cooling performance corresponds to the K doped compound. The evolution from ferromagnetic to paramagnetic state was also determined with electron paramagnetic resonance spectroscopy. The temperature dependence of the resistivity shows a semiconductor character in La0.9Ba0.1MnO3 and 2 maxima of metal-insulator (M-I) transitions in the K doped sample. Enhanced magnetoresistance effects have been observed in La0.9K0.1MnO3 close to the ferromagnetic-paramagnetic transition temperature.