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Free keywords:
rare-earth chalcogenides; flux; crystal growth; crystal structure; optical and magnetic properties
Abstract:
Brown needle-like crystals of CaEr2S4 were isolated as the major product from a reaction of elements and binary sulfides by a two-step flux technique. CaEr2S4 Crystallizes in the orthorhombic space group Pnma with a = 12.845(4), b = 3.862(4), c = 13.001(2) angstrom, V = 645.0(7) angstrom(3), Z = 4, F(000) = 880, mu(MoKa) = 27.794 mm(-1), the final R = 0.0528 and wR = 0.0562 for 1070 observed reflections with I > 3 sigma(I). The CaEr2S4 structure forms a three-dimensional framework that consists of interconnected tetra-octahedral Er4S18 fragments. Ca2+ cations, in a monocapped trigonal prism geometry, are stuffed in two parallel rows into the one-dimensional channels along the b direction. CaEr2S4 is an infrared-transparent semiconductor with a band gap of 1.81 eV. Magnetic susceptibility measurements over 6 similar to 300 K indicate a Curie-Weiss paramagnetic behavior for the phase, with an effective magnetic moment of 9.64(1) mu(B) per Er3+ ion.
