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The low field magnetocaloric effect (MCE) of Gd-based amorphous alloys is examined. The results have shown that the melt-spun amorphous Gd-Co ribbons have displayed large magnetic entropy change and refrigerant capacity (RC) in a low field, making it good candidate for the practical magnetic refrigeration.

A study was conducted to examine the phase transitions, magnetocaloric effect, and magnetoresistance in [Ni.sub.50-x][Co.sub.x][Mn.sub.39][Sb.sub.11] (x = 0-11) ferromagnetic shape memory alloys. The results revealed the potential application of [Ni.sub.50-x][Co.sub.x][Mn.sub.39][Sb.sub.11] alloys in magnetic refrigeration and magnetic sensors.

The magnetic entropy changes and magnetoresistance (MR) are analyzed in [Ni.sub.45][Mn.sub.42][Cr.sub.2][Sn.sub.11] ferromagnetic shape memory alloy near the martensitic transition temperature. The temperature and magnetic field induced martersitic transitions is shown to be the origin of the large magnetic entropy change and MR in [Ni.sub.45][Mn.sub.42][Cr.sub.2][Sn.sub.11] ferromagnetic shape memory alloy.

Abstract: A series of (La1−x Gd x )1.4Ca1.6Mn2O7 (x=0–0.1) compounds were prepared by solid state reaction. With the increase of Gd content, Curie temperature decreases from 259K to 192K. These compounds show constant magnetic entropy changes (ΔS M) of 3.0–3.1J/kgK in the field of 1T. In their composite materials, a plateau in ΔS M with enhanced refrigerant capacity can be obtained, indicating that they are advantageous for an Ericsson refrigeration cycle. In addition, they have other advantages such as negligible magnetic hysteresis, small eddy loss, and high chemical stability. These properties make (La1−x Gd x )1.4Ca1.6Mn2O7 good candidate for the practical magnetic refrigeration. [Copyright &y& Elsevier]

Abstract: Nanopowders were synthesized by the combustion method. To achieve high transparency, Y2O3 particulares were used as matrix materials, La3+ and Nd3+ were used as dopants, and polyethyleneglycol (PEG) was used as dispersants for the sintering under vacuum 10−3 Pa and 1600 °C for 6 h. The precursor and powders calcined at different temperatures were characterized using TG-DTA, XRD, BET and FESEM. Results showed that La3+ and Nd3+ were completely dissolved into the cubic lattice of Y2O3. The sizes of the nanopowders were uniform and spherical-like. The particle sizes of powders gradually increased with increasing the calcination temperature. The dispersant can effectively prevent the powders from the agglomeration, and the particle sizes of powders gradually increased with increasing citric acid. The transmittance of the nanopowders was close to its theoretical value. [Copyright &y& Elsevier]

Abstract: First-principles calculations are performed to study on alloying stability, elastic properties, ductility and electronic properties of AlCu2X (X=Ti, Mn, Zr, or Hf) intermetallics within the generalized gradient approximation. The obtained lattice parameters for all intermetallics considered are very close to the corresponding experimental values. The calculated cohesive energy (E coh) and formation energy (ΔH) show that the AlCu2Zr crystal structure is more stable, and the alloying ability of AlCu2Zr is also stronger. The calculated density of states of these phases indicates that the highest structural stability of AlCu2Zr is attributed to the lower value of the DOS at the Fermi level, i.e., N(E F ). The elastic constants C ij of these phases were calculated, and the bulk modulus B, shear modulus G were derived from the elastic constants. The calculations on the ratio of bulk modulus to shear modulus reveal that the ductility of AlCu2Zr is better than AlCu2Mn, AlCu2Ti and AlCu2Hf. In addition, the work functions (WF) and surface energies of (100) and (110) surfaces of AlCu2X intermetallics are also investigated. For the four AlCu2X intermetallics, the work function of (110) surface is higher than that of (100), and the surface with a higher work function is prone to have a lower surface energy. Furthermore, both shear modulus and WF decrease, and changes in both WF and bulk modulus of the four intermetallics have a similar trend, except for AlCu2Ti and AlCu2Hf. It is also revealed that with the increase of WF, the ductility decrease, which is attributed to a change in the nature of the atomic bonding or in the electronic structure induced by the alloying. [Copyright &y& Elsevier]

Abstract: The composition dependences of the martensitic transformation and the magnetocaloric effect in Ni50−x Mn38+x In12 () ferromagnetic shape memory alloys are investigated. With the increase of Mn content, the martensitic transformation temperatures decrease rapidly. Under a low magnetic field of 10 kOe, the maximum magnetic entropy changes are 5.0, 5.8, and 7.6 J/kg K, for , and 6, respectively. The large low-field magnetocaloric effect and adjustable working temperature suggest that Ni50−x Mn38+x In12 alloys should have great potential as magnetic refrigerants. [Copyright &y& Elsevier]

Abstract: The MnNiGe-based and MnCoGe-based intermetallic compounds usually exhibit giant magnetocaloric effects at the TiNiSi-to-Ni2In-type magnetostructural transitions. However, the high concentrations of costly Ge element give rise to relatively high raw-material costs for these alloys. In this work, we realized the TiNiSi-to-Ni2In-type magnetostructural transitions in Mn16Fe16Ni34Si34−x Ge x system which possesses largely reduced Ge-concentrations. Large magnetic entropy changes were observed under relatively low field in a wide temperature range including room temperature. [Copyright &y& Elsevier]