In this study, La 0.63 Sr 0.2 Nd 0.17 MnO 3 was synthesized by the sol-gel method, and its structural, morphological, magnetic, and magnetocaloric effects were investigated. The structural properties were analyzed by x-ray diffraction (XRD), and scanning electron microscopy (SEM) was used to characterize the morphology. An integrated magnetic measurement system was used to determine the magnetic properties. La 0.63 Sr 0.2 Nd 0.17 MnO 3 crystallized in a hexagonal crystal system with space group R -3 c . This was also confirmed by Rietveld refinement of the x-ray data from La 0.63 Sr 0.2 Nd 0.17 MnO 3 . With the doping of Nd 3+ , the cell volume decreases, which can be explained by the angles and bond lengths of the bonds between the Mn and O ions and the distortion of the lattice. Near the Curie temperature, La 0.63 Sr 0.2 Nd 0.17 MnO 3 exhibits significant magnetocaloric effects. The magnetic study of La 0.63 Sr 0.2 Nd 0.17 MnO 3 suggests that the transition from the paramagnetic to ferromagnetic phase can occur near the Curie temperature. The maximum magnetic entropy change and relative cooling power (RCP) of La 0.63 Sr 0.2 Nd 0.17 MnO 3 (298 K, 3 T) are 2.70 J/(kg K) and 135 (J/kg), respectively. The effect of f -orbitals on the magnetic properties of La 0.8 Sr 0.2 MnO 3 was investigated by first-principles calculations in density functional theory. Thus, it can be concluded that the magnetocaloric effects of the material after doping with f -orbital ions (Nd 3+ ) is enhanced compared to La 0.8 Sr 0.2 MnO 3 .
Xicai Liu,Huan Wang,Dongcheng Yang,Fangli Jing,Hailong Qiu,Hongjun Liu,Zhanggui Hu
Trivalent lanthanoid ions (Ln3+) with substantial inherency have been utilized in luminescent materials and photonic devices for decades. Because the periodic physicochemical properties of lanthanoid compounds have been found to be closely related to the regular f-configuration of the elements, it is essential to study the interaction between the f-electrons and the circumstances for developing new applications. Two-dimensional transition metal dichalcogenides (2D-TMDs) manifest as excellent matrices for tunable electronic structures owing to their chemical accessibility and physical sensitivity. Herein, a novel method is proposed for the fabrication of Ln3+ substitutional doped MoS2 using a Na2MoS4 solution precursor. Monolayers doped with all Ln3+ ions (except Pm3+) are synthesized, which is confirmed by structural characterization. Their shrunk Raman frequency differences and the blue-shifting and intensity boosting of their photoluminescence (PL) peaks are observed. Periodic trends are discovered in the PL spectra, which are sensitive to specific elements. The results reveal the ordered interaction between f-orbitals and the host possessing an appreciable coulombic field, spin–orbital coupling, and a crystal field. This work offers a crucial extension of lanthanoid laws and a new approach to the modulation of the properties of 2D crystals.
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