Dielectric spectra of doped AgBr emulsion systems. Effect of Hg2+, I– and Br– ions

Abstract

The influence of doped Hg²⁺, I^– and Br^– ions on the dielectric spectra of octahedral AgBr emulsions has been studied. Br^– causes Hg²⁺ to be substituted for Ag⁺ in the surface lattice of AgBr. The dielectric absorption peak of the AgBr emulsion shifts to lower frequency following doping with Hg²⁺ because the dielectric conductivity of the sample, σ₂, decreases. When the Hg²⁺ content was 1.3 × 10^–2 mol mol_AgBr^–1 the dielectric absorption peak no longer continued to shift to lower frequency. In the case of doping with Hg²⁺ and I^– simultaneously, when the dopant contents were ⩽ 1.0 × 10^–2 I^– and ⩽ 6.5 × 10^–3 Hg²⁺ mol mol_AgBr^–1, f_max increased; when the dopant contents were 1.4 × 10^–2 I^– and 9.1 × 10^–3 Hg²⁺ mol mol_AgBr^–1, f_max decreased. However, Δlogf_max in both cases is less than that for doping with Hg²⁺ or I^– alone.