Liquid ammonia mediated metathesis: synthesis of binary metal chalcogenides and pnictides.

ABSTRACT

Addition of stoichiometric amounts of low valent metal halides to liquid ammonia solutions of disodium chalcogenide (Na(2)E; E = S, Se, Te) afforded a range of both crystalline (PbE (E = S, Se, Te), TlE (E = S, Se), Tl(5)Te(3), Ag(2)E (E = S, Se, Te)) and X-ray amorphous (MS (M = Ni, Cu, Zn, Cd, Hg), M(2)E(3) (M = Ga, In; E = S, Se, Te), HgE (E = Se, Te), CuE (E = S, Se, Te), Cu(2)S) metal chalcogenides in good yield (95%). Reactions between metal halides and sodium pnictides (Na(3)Pn; Pn = As, Sb) in liquid ammonia also afforded X-ray amorphous material (M(3)Pn(2), M = Zn, Cd; MPn, M = Fe, Co, Ni) in good yield (95%). Isolation of the metal chalcogenides and pnictides was achieved through washing with CS(2) and distilled water. All reactions were complete within 36 h. Products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDXA), electron probe analysis, FT-IR spectroscopy, Raman spectroscopy, microanalysis, and band gap measurements. Annealing amorphous material at 250-300 degrees C for 48 h induced sufficient crystallinity for analysis by X-ray powder diffraction.