Plastic Flow of Solid Mixtures of Li2SO4 and K2SO4

Abstract

The addition of K2SO4 to Li2SO4 causes a considerable change in the rheological properties of the cubic high temperature modification. A simple device for relative measurements of the plastic flow of the salt consisted of a sphere of stainless steel at the end of a steel rod on top of which weights were hung in order to obtain a suitable penetration rate through the salt. This rate depended on the composition of the mixture as well as on the thermal pretreatment of the salt. The temperature dependence was strong; a crude estimation gave an “activation energy” of the order of 2 x 105 cal/mole, i. e. more than an order of magnitude higher than for electrical conductivity or cation self-diffusion. This result is in agreement with the interpretation of the electrical conductivity as being due solely to cation transport.