Periodic precipitation (liesegang phenomenon) in solid silver—i. experimental

Abstract

The Liesegang phenomenon (periodic precipitation) has been studied experimentally in a solid state system. Single crystals of silver were annealed in some partial pressure of oxygen to saturation and were then annealed in a partial pressure of hydrogen at 800°C. Hydrogen diffuses into the silver and reacts with the dissolved oxygen to form water vapor which precipitates in the form of bubbles. Under certain conditions these bubbles have been found to form in bands which obey Jablczynski's relationship, that is, the spacing coefficient, which is defined as, the ratio of the distance to successive bands from the diffusion interface, is a constant. The spacing coefficients were studied in three silvers of different purities as a function of the concentration of the hydrogen and oxygen. It was found that the spacing coefficient decreased when either the concentration of hydrogen (keeping the oxygen concentration fixed) or oxygen (keeping the hydrogen concentration fixed) was increased, and it increased when the purity was decreased.