The magnetic and magnetocaloric properties for the Nd12Co6Pb compound were investigated. The Curie temperature Tc of the magnetic transition of Nd12Co6Pb compound is 194 K. The experimentally determined magnetic effective paramagnetic moment isμeff= 12.36μB per formula unit (3.49μb per Nd atom). The maximum magnetic entropy change in the low magnetic field changes of 0 ~ 2 T for the Nd12Co6Pb compound is about 215.0 J·mole-1·K-1.
A new ternary compound Al14 Dy5Si was discovered and studied by means of X-ray powder diffraction technique. The ternary compound Al14Dy5Si has a hexagonal BaPb3-type structure, space group R 3m(No. 166), the lattice parameters a =0.61482(1) nm, c =2.09780(2) nm. The crystal structure of the compound Al14Dy5Si was successfully refined by using Rietveld method from X-ray diffraction data. The R-factors of Rietveld refinement are RP= 0.091 and Rwp = 0.120, respectively. The thermal dependence of the magnetization (M-T curves) for the compound was measured by a vibrating sample magnetometer. The experimentally determined magnetic effective paramagnetic moment isμeff = 23.22μB per formula unit (10.36μB per Dy atom).
Thermomagnetic properties of the new compound Dy6FeSb2 were investigated by vibrating sample magnetometer. The sample of the compound Dy6FeSb2 showed soft magnetic behavior in the investigated temperature range from 85 to 300 K and the ferromagnetic-paramagnetic transition of the compound was a second-order transition. The Landau theory of second-order phase transition was employed to investigate the thermodynamic transition temperature and the specific heat. The calculated transition temperature and the specific heat jump at Currie point of the compound were 143 K and 47.2 J·kg-1·K-1, respectively.
The new ternary compound Al14NdsSi has been studied by means of the X-ray powder diffraction technique and the Rietveld method. The ternary compound Al14Nd5Si has a hexagonal Ni3Sn-type structure with space group P63/mmc （No.194）, the lattice parameters are a = 0.64470 （2） nm and c = 0.45926 （1） nm. The Smith and Snyder figure of merit for the index, FN, is F30 = 97.8 （30）. The X-ray diffraction data indicated that the crystal structure of the compound Al14Nd5Si has been successfully refined by the Rietveld method. The R-factors of Rietveld refinement are Rp = 0.088 and Rwp = 0.120, respectively. The thermal dependence of magnetization for the compound was measured by a vibrating sample magnetometer. The experimentally determined magnetic effective paramagnetic moment is μeff= 3.60 μB per Nd atom. The paramagnetic Currie temperature θp = -33.7 K was also obtained from the Currie-Weiss law.
HE WeiZHANG JiliangZENG LingminYU MeihuaXIA Xiuwen
