材料期刊网

A compound Pr5Co19B6 has been synthesized successfully and its crystal structure has been investigated by x-ray powder diffraction. It belongs to the Rm+nCo5m+3nB2n (R = rare earth) family with m = 2 and n = 3. The space group is P6/mmm. The lattice parameters are alpha = 5.1264(4) Angstrom and c = 16.5602(6) Angstrom. Each unit cell contains one formula unit of Pr5Co19B6, and there are nine kinds of equivalent positions in each unit cell, i.e., 1b, 2e(1), 2e(2), 4h(1), 6i(1), 6i(2), 3f, 2d, and 4h(2), which are occupied by 1Pr((1)), 2Pr((2)), 2Pr((3)), 4Co((1)), 6Co((2)), 6Co((3)), 3Co((4)), 2B((1)), and 4B((2)), respectively. Magnetic measurements indicate that this compound is ferromagnetic with a Curie temperature of 380 K. Its saturation magnetic moment at 5 K and room temperature an 23.7 mu(B) /f.u. and 11.9 mu(B) /f.u., respectively. Based on the experimental results of the saturation magnetization, three kinds of Co sites with different magnetic moment are proposed. The Pr5Co19B6 compound exhibits huge planar anisotropy with an anisotropy held of 250 kOe at 5 K. No spin reorientation was detected from the temperature dependence of the magnetization and the temperature dependence of the ac susceptibility curves from 5 FC to room temperature. The behavior of magnetocrystalline anisotropy is analyzed using the single-ion model.