Unusual crystal-lattice behaviour of CeSb at ambient pressure

The temperature dependence of lattice constant of CeSb in the temperature range from 17 K to 280 K as measured by the X-ray diffraction technique exhibits an unusual minimum around 45 K. The origin of this exotic lattice behaviour has been disclosed in this article. Our model analysis shows that two types of Ce ions with different sizes, called Γ₇and Γ₈ Ce ions, appear in the CeSb lattice in its paramagnetic phase to exhibit its unusual temperature dependence of lattice constant. The calculated lattice constant difference  (a₇(0)- a₈(0)) at 0 K between a CeSb lattice with pure Γ₇ Ce ions and a CeSb lattice with pure Γ₈ Ce ions is 0.0081 Å, which is very small. The lattice contraction δ, defined by  δ={(a₇(0)- a₈(0)}/a₇₍₀) in the present analysis, is 1.263´10^-3 .

Keywords: Cerium monopnictides, CeSb, low carrier-density, p-f mixing, X-ray diffraction

J.Natn.Sci.Foundation Sri Lanka 2010 38 (3):201-205

Doi: 10.4038/jnsfsr.v38i3.2310