Abstract
Polycrystalline La0.8K0.2-xPbxMnO3 (x = 0.05, 0.10, 0.15, 0.20) ceramics were successfully prepared by flash combustion route and their structural, morphological, magnetic and magnetocaloric properties were investigated. Structural analyses using X-ray diffraction reveal that all samples are crystallized in the rhombohedral structure and belong to R3‾c space group. The increase of Pb doping does not modify the crystalline structure but changes the grain size and lattice parameters. X-ray photoelectron spectroscopy (XPS) fitting results of Mn 2p peaks confirmed the coexistence of Mn3+ and Mn4+ ions which contribute to the double exchange interactions improving the ferromagnetic order in the samples. The magnetization's temperature and magnetic field dependences indicate a second-order ferromagnetic-paramagnetic transition of the ceramics. A significant magnetic entropy change near room temperature was observed for La0.8K0.1Pb0.1MnO3,showing considerable magnetocaloric properties. Furthermore, electron paramagnetic resonance spectroscopy (EPR) was also used to examine the ferromagnetic-paramagnetic transition.
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