Structural and magnetic characterization of the alloy system

Abstract

The synthesis, structural characterization and magnetic properties of the alloy system CuAl1??xCrxS2 (x = 0:10 and x = 0:20) is reported. Both samples were synthesized using the direct fusion technique. Chemical analysis (EDX) con rmed the stoichiometric ratio for both concentrations. The powder difraction patterns were indexed, and both principal phases crystallize with tetragonal symmetry and unit cell parameters a = 5:3317(1) A, c = 10:4059(2) A for x = 0:10 and a = 5:3331(1) A, c = 10:4117(2) A for x = 0:20. These materials are isomorphic with the chalcopyrite structure that crystallizes in the space group I42d. The system behaves paramagnetic for x = 0:10 and antiferromagnetic for x = 0:20 with Néel temperature 20 K. The EPR linewidth and g factor are temperature independent for x = 0:10, while for x = 0:20 the linewidth follows a Korringa-like behavior ( H= T = 0:39 mT/K) as a function of temperature. These results are discussed in terms of nearest-neighbor Cr+3 (S = 3=2) spin-coupled pairs.