Investigation Of Temperature Dependent Characteristics Of Compound TbCo₂ Using Neutron Powder Diffraction Technique

Abstract

The structure, magnetization and magnetostriction of Laves phase compound TbCo2 were investigated by temperature dependent high resolution neutron powder diffraction. The compound crystallizes in the cubic Laves phase C15 structure above its Curie temperature, TC and exhibits a rhombohedral distortion (space group R3m) below TC. By an appropriate extrapolation of the temperature factor of Co atom above TC, the Rietveld refinement of the neutron powder diffraction data of the rhombohedral structure converges satisfactorily and reveals that the moments of Co₁ (3b) and Co₂ (9e) are almost equal. The moment follows well the Brillouin function. The total magnetic moment of TbCo2 was found to be 5.8μB/ f.u; the anisotropic magnetostriction constant λIII is about 4.6 x 10^-3 and the volume magnetostriction ωs is about 8.7 x 10^-3 at 14K.

Keywords: Magnetic structure; neutron powder diffraction; laves phase; rhombohedral distortion.

Nigerian Journal of Physics Vol. 19 (1) 2007: pp. 31-38