It was shown, for the first time, that films consisting of a transition-metal-based structure formed (via thermal diffusion of intracrystalline impurities) on the surface of alkali-halide (LiF, NaF) crystals activated by transition metals Co, Ni, or Mn. The thickness, density, and composition of the films were shown to be different, depending upon the heat treatment conditions. The crystals were annealed at 473 to 1073K in vacuum or air. The surface structures which formed upon annealing in vacuum exhibited magnetic properties. The films were studied by using optical, X-ray fluorescence, and electron spectroscopy to reveal the mechanisms of transition-metal film formation during thermal annealing.

Metallic Films Forming on the Surface of Alkali-Halide Crystals During Thermal Diffusion of Intracrystalline Impurities. L.I.Bryukvina, E.A.Ermolaeva, S.N.Pidgurskiĭ, L.F.Suvorova, V.M.Khulugurov: Physics of the Solid State, 2006, 48[1], 68-72