Thermal expansion of Mn2-xCrxSb single crystals

The thermal expansion Delta l/l has been measured and the thermal expansion coefficient a determined as a function of temperature and in the crystalline a- and c-directions of three Mn2-xCrxSb single crystals, x=0.10, 0.05, 0.03. In both lattice directions ct is different in the antiferromagnetic (afm) and ferrimagnetic (fi) phases (for example, x=0.03: alpha(a) = 2.5 x 10(-5) K-1; T less than or equal to T-s, alpha(a) = 5 x 10(-5) K-1; T greater than or equal to T-s), suggesting that the first-order afm-fi phase transition (T) in these crystals should be described as a triggered coupled spin-lattice phase transition rather than as driven by lattice entropy. (C) 1999 Published by Elsevier Science S.A.