Thermal transformation of layered zinc hydroxide chloride

Zinc hydroxide chloride, Zn.sub.5(OH).sub.8Cl.sub.2·H.sub.2O, belongs to a special group of layered materials which are used in a wide variety of commercial applications. During the heating, Zn.sub.5(OH).sub.8Cl.sub.2·H.sub.2O undergoes a complex transformation which involves several overlapping stages and highly depends on the experimental conditions. Although it is well established that the thermal transformation of Zn.sub.5(OH).sub.8Cl.sub.2·H.sub.2O leads to the formation of ZnO as final product, there is still no generally accepted mechanism explaining the intermediate stages of this process. This review provides a summary of the studies devoted to this topic complemented by critical data assessment and generalisation of the established information. We hope that the review conveys to the reader state of the art of this problem and provides baseline knowledge required for complete understanding of thermal behaviour of this material.