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Microscopic observations of electroluminescent emission from ZnS crystals activated with Cu, Cu :Pb, or Ag have shown that the typical emitting entity is a narrow line. These lines lie in directions of the wurtzite structure in planar regions associated with stacking faults or closely spaced alternations in crystai structure. A model of electroluminescence involving linear physical defects is proposed for the origin of the lines and their observed dependence on voltage, frequency, and phase of the applied electric field.

Air-stable, single-domain Fe and Fe-Co particles prepared by the reaction of the metal salts with aqueous borohydride have higher coercivities and axial ratios if prepared in a magnetic field. Oxide and boride impurities are indicated by elemental analyses and lowered saturation magnetizations. Studies of coercivitiesand magnetizations as a function of temperature, remanence ratios, and rotational hysteresis measurements indicate single-domain behavior with coercivity controlled by shape and somewhat by crystalline anisotropy in approximate agreement with the predictions of the Jacobs-Bean “chain of spheres” model.