Convenient, room-temperature liquid ammonia routes to metal chalcogenides

Abstract

Reaction of sulfur, selenium or tellurium with elemental metals in liquid ammonia at room temperature in a pressure vessel produced metal chalcogenides ME (M = Ca, Sr, Ba, Eu, Yb, Ni, Zn, Cd, Hg, Sn or Pb; E = S, Se or Te), Ag ₂ E, solid solutions of mixed-metal chalcogenides M _x M′ _y E _z (x + y = 1, z = 1 or 2), and metal-mixed chalcogenides MS _x Se _y . Products showed a range of crystallite sizes from 700 Å for PbSe and Ag ₂ S to essentially amorphous (ZnS). Heating at 250–300 °C under vacuum for 2 h induced crystallinity in the amorphous powders. The pre- and post-heated metal chalcogenides were analysed by X-ray powder diffraction, Fourier-transform IR, Raman microscopy, scanning electron microscopy-energy dispersive analysis of X-rays, electron microprobe, X-ray photoelectron spectroscopy, elemental analysis and magnetic susceptibility studies.