Structure and Magnetocaloric Properties of Two Cadmium Gadolinium Borates.

A new pyrochlore compound Sn2Mn2O7 has been synthesized to investigate its structural, optical, magnetic, and magnetocaloric properties. The refinement of the structure by Le Bail fitting reveals that the compound crystallizes into a monoclinic structure with P2/m space group. The reflectance spectrum has been recorded on a UV–vis spectrometer between the 200 and 800 nm wavelength range. The optical bandgap of the compound is found to be ≈3.06 eV. The skin depth, refractive index, extinction coefficient, and optical conductivity have also been computed. A magnetic transition has been observed at TC≈41 K in the magnetization versus temperature behavior. Arrott's plot confirms a second‐order magnetic phase transition, which is also established by the scaling analysis of magnetic entropy change. On the application of a 5 T magnetic field, the compound shows a maximum magnetic entropy change of 2.94 J kg−1 K−1 at a temperature ≈41 K with a relative cooling power of 41 J kg−1. The maximum magnetic entropy change values are higher than that reported for the Fe2Mn2O7 and smaller than for Al2Mn2O7 compound.

Structure, magnetism and magnetic thermal properties of heavy rare earth Tb1–xTmxFeO3 (x=0.00, 0.15, 0.25) polycrystalline samples

Magnetic properties and cryogenic magnetocaloric effect in α-Gd2(MoO4)3 compound

Effect of Bi-doping on structural, magneto-caloric and magneto-resistive properties of La0.67- xBixCa0.33MnO3 perovskites

Effect of Nd-substitution on the structural, magnetic and magnetocaloric properties of La0.67-xNdxCa0.13Ba0.2MnO3 manganites

This paper reports the effect of Cu doping in first order phase transition material Mn1.28Fe0.67P0.48Si0.52 on its phase structure, magnetocaloric effect and mechanical properties. The results of XRD, SEM and EDS analysis show that the Mn1.28Fe0.67P0.48Si0.52 in this composite forms Fe2P hexagonal structure and the space group is P-62m;Most of Cu exists as a simple substance, and a small amount of Cu and Mn form a solid solution. When the mass ratio of Cu reaches 10:4, the (Mn,Fe)3Si phase appears in Mn1.28Fe0.67P0.48Si0.52. The magnetic measurement results show that the saturation magnetization of Mn1.28Fe0.67P0.48Si0.52 after Cu doping has no obvious change, the Curie temperature decreases, and the thermal hysteresis increases. The maximum magnetic entropy change becomes smaller as the Cu content increases. Under a 1.5 T external magnetic field, the maximum magnetic entropy ΔSm of the composite decreases rapidly from 11 J/kg·K at x = 0 to 4 J/kg·K at x = 5,the half width of the magnetic entropy change gradually increases. The Vickers hardness of the composite is reduced, the compressive strength has been greatly improved, and the mechanical properties have been significantly enhanced after Cu doping.

Structural, magnetic properties, critical behaviors and magnetic entropy changes of La0.7-x Gd x Ca0.3MnO3 (x=0, 0.05, 0.1) polycrystalline manganites have been investigated. The X-ray diffraction characterization shows that all the samples can be well indexed on an orthorhombic structure with Pnma space group. Magnetic measurements show that polycrystalline samples sequentially display the characteristics of cluster spin glass states, ferromagnetic states, ferromagnetic paramagnetic coexistence states and pure paramagnetic states with increasing temperature. The Curie temperature (Tc) increases with increasing doping concentration x, and the ferromagnetic paramagnetic transform into a second-order phase transitions near the Tc. Critical behaviors have been studied through the modified Arrott plots and the Kouvel-Fisher method. The critical exponents of polycrystalline samples are determined to be close to the critical exponents of the tricritical mean field model (x=0), 3D Ising model (x=0.05) and 3D Heisenberg model (x=0.1), indicating that their ferromagnetic coupling may be the result of the short-range interactions between spins in this system. The maximum magnetic entropy changes reach values of 3.99 J/(kg·K), 2.81 J/(kg·K) and 4.20 J/(kg·K) at the magnetic field of 7T, and the relative cooling power (RCP) values of La0.7-x Gd x Ca0.3MnO3 (x=0, 0.05, 0.1) are 478.8 J/kg, 431.1 J/kg and 536.98 J/kg respectively.

Structural and cryogenic magnetic properties of the RE2MoO6 (RE = Er and Ho) compounds

Effect of A-site deficiency on the structural and magnetic properties of La0.8−x□xNa0.2−x□xMnO3 oxides and estimation of the magnetocaloric behavior

Study on synthesis and magnetocaloric effect of room temperature refrigeration materials La0.8-xSr0.2SmxMnO3 (0 ≤ x ≤ 0.2) by sol–gel method

Magnetic properties and magnetic entropy change of perovskite manganites La0.9–xEuxSr0.1MnO3 (x=0.000, 0.075) by experimental method and numerical fitting

Magnetocaloric properties of the A-site co-doping double-perovskite of Sr2FeMoO6

The structure and the magnetocaloric effect of single-phased Mn0.997Fe0.003As were studied with X-ray diffraction and vibrating sample magnetometry. In the Mn0.997Fe0.003As sample, the firstorder ferromagnetic-to-paramagnetic transition was observed near the Curie temperature (TC), namely at 308 K for the quenched sample and at 313 K for the slowly-cooled sample. This magnetic transition was accompanied by a structural transition from a hexagonal (NiAs-type) to an orthorhombic (MnP-type) structure. We also observed that after the heat treatment, the sample showed a large change in the magnetocaloric effect depending on the cooling conditions. From the isothermal M-H curves, the changes in the magnetic entropy (−ΔSM) were determined at temperatures between 280 and 320 K for different magnetic fields. For the sintered samples under slow cooling and water quenching, the maximum magnetic entropy changes at a magnetic field of 1.5 T were 19.6 and 32.2 J/kg K, respectively. Such a significant difference between the maximum entropy changes is due to the degree of the structure distortion, which depends on the heat treatment.

Effect of Co-doping on structural, magnetic and magnetocaloric properties of La0.67Ca0.13Ba0.2Mn1-xCoxO3 (x = 0, 0.02, 0.04, 0.06, 0.08, 0.1) manganites

Effect of Ni alloying on the microstructure and magnetocaloric properties of Gd-based metallic microfibers