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The effects of A-site cation size mismatch on La0.7 − xNdxCa0.3 − y(Ba,Sr)yMnO3 perovskite materials with a constant A-site average ionic radius ⟨rA⟩ = 1.2052 Å have been investigated. Polycrystalline samples have been prepared through the standard solid-state reaction method at high temperatures, and their structures, magnetic properties, and magnetocaloric effect (MCE) have been investigated in detail. X-ray diffraction patterns show that all of the samples crystallized in an orthorhombic structure with the space group Pnma. XPS analysis confirmed the Mn3+/Mn4+ ratio remained constant as σ2 was varied. Meanwhile, upon increasing σ2 from 0.0002 to 0.007, the Curie temperature (TC) decreased linearly from 254 K to 108 K. Based on M-H isotherms, Arrott plots and the maximum magnetic entropy prove a crossover of first-to-second-order transition with increasing σ2. Samples with σ2 = 0.0002, 0.001, and 0.003 exhibited a first-order transition and had larger MCEs than those showing a second-order transition. [ABSTRACT FROM AUTHOR]

Rare earth noble metals compounds have a variety of physical properties, such as heavy fermions, topological, superconductivity, and so on. In this paper, the cohesive energy, mechanical, electrical, and magnetic properties of REAuBi2 (RE=La-Pr, Sm) and the mechanical properties of REAu (RE=La-Pr, Sm) were studied by first-principles calculations. The calculated cohesive energies of REAuBi2 are negative, indicating the stable structures of REAuBi2. The comparison between the mechanical properties of REAuBi2 and REAu, including the bulk modulus, shear modulus, Young's modulus, and Poisson's ratio, under ideal conditions is carried out. Electronic density of states, band structure, and phonon spectrum of REAuBi2 are also studied and discussed. LaAuBi2 alloy is in the paramagnetic state, while PrAuBi2 and SmAuBi2 alloys are in antiferromagnetic order obtained by the results of Birch–Murnagha equation fitting of cell volume and energy. [ABSTRACT FROM AUTHOR]

In the family compounds of RMn6Ge6, GdMn6Ge6 exhibits excellent magnetic properties and a complex magnetic transition behavior. The samples of GdMn6Ge6−xSix were successful prepared by a vacuum arc furnace. The XRD analysis and Rietveld refinement results show that GdMn6Ge6−xSix crystallize in a hexagonal HfFe6Ge6-type structure with space group P6/mmm, and their lattice parameters a and c decrease with the increasing Si content. The M-T curves in the range of 100–600 K indicates that the compounds experienced two magnetic transitions (AFM-FM and FM-PM) and a large thermal hysteresis between ZFC and FCC curves. The AFM-FM transition occurred at Tt for GdMn6Ge6-xSix is a first-order phase transition and the FM-PM transition belongs to a second-order one. The magnetic transition temperature Tt is greatly influenced by the Si content, and the Curie temperature (Tc) for the all samples is roughly the same. The −∆SM for the x = 0, 0.2, 0.4, 0.6 compounds under the applied magnetic field of 1.6 T are 0.83, 1.06, 1.21 and 1.19 J kg−1·K−1 around 486 K, respectively. This relatively large −∆SM of GdMn6Ge6−xSix occurred in a relatively high temperature region and under low applied magnetic field provide a potential material choices in new magnetic refrigeration application. [ABSTRACT FROM AUTHOR]

Mn8Ga5 alloy has certain significance in the study of materials for magnetic refrigeration applications due to its low coercivity. In this paper, the structure, magnetic properties and magnetocaloric effects (MCE) of Mn8−xCrxGa5 (x = 1.3, 1.7) polycrystalline alloys were first studied by using X-ray diffraction (XRD) technique, scanning electron microscope (SEM), energy-dispersion (EDS) analysis and magnetization measurement. The two samples crystallized in a cubic (Zn8Cu5)-type structure with space group of I-43 m (No. 217). The lattice constants and crystallite sizes of Mn8−xCrxGa5 increase with the increase of Cr concentration. As the Cr content increases, the Curie temperature (Tc) of Mn8−xCrxGa5 (x = 1.3, 1.7) is increased from 145 to 187 K. The saturation magnetic moments of Mn8−xCrxGa5 are 33.8 (x = 1.3) and 36.6 (x = 1.7) emu/g under the magnetic field of 16 kOe at 80 K, respectively. A second-order magnetic phase transition occurred in Mn8−xCrxGa5 alloy samples. The maximum magnetic entropy changes (|∆SM|) of Mn8−xCrxGa5 are 0.9 (x = 1.3) and 0.8 J·kg−1·K−1 (x = 1.7), and the relative cooling power (RCP) values are 25 (x = 1.3) and 17 J/kg (x = 1.7) under 15 kOe magnetic field. [ABSTRACT FROM AUTHOR]

Series samples MnBi1-xGdx (x = 0, 0.04, 0.08, 0.12, and 0.16) were prepared and studied the structure and magnetic properties. The Rietveld refinement results showed that the low-temperature phase MnBi content in these samples is above 78% and the doped atoms occupied the position of Bi in the MnBi crystal structure. The Debye temperature is founding to decrease with increasing doping. The Curie temperature, paramagnetic to ferromagnetic transition temperature, thermal hysteresis, saturation magnetization, and coercive force of the samples change significantly with increasing doping content. Within a temperature range of 300–500 K, a positive coercivity temperature coefficient β existed. This work helps MnBi-Gd as a candidate for high-temperature magnetic material applications and contributes to the development of tailoring magnetic properties. [ABSTRACT FROM AUTHOR]