ABSTRACT
Small sized colloid elemental silver particles formed in gelatin layers during the development of silver halide photographic emulsions find a mention about more than 40 years ago [1]. In a number of studies, there are indications of the existence of a separate phase of the elemental silver consisting of nanoparticles and are received as a result of photochemical reduction of Ag(I) salts. It appeared lately in the literature [2-11]. It has been noted that [10, 11], during the development of gelatin layers of silver halide photographic emulsions by alkaline water solutions containing tin(II) dichloride and some inorganic or organic substance forming stable coordination compounds with Ag(I), the formation of elemental silver occurs too. However, the gelatin layer is either tinged brown or red but not black color due to the fact that it takes place at standard development by using hydroquinone developers. It is significant to note that with the increase of optical densities of the gelatin layer with elemental silver, red tone coloring of gelatin layer becomes more and more clearly expressed. The similar phenomenon takes place when instead of silver halide AgHal in gelatin matrix, there is such silver(I) compound as silver(I) hexacyanoferrate(II) Ag4[Fe(CN)6]. Whether this totality of particles is a novel phase of elemental silver? Or is it only a variety of known phases of the given simple substance? These questions remain unanswered till now and deserve special consideration.
