Studies of zinc-chromium hydroxy salts. I. Thermal decomposition of [Zn 2Cr(OH) 6] X · nH 2O, where [formula omitted

Abstract

We have characterized the layered anion exchange compounds [Zn 2Cr(OH) 6] X · nH 2O, where X −= F −, CI −, Br −, I −, 1 2 CO 2− 3, and NO − 3 , and studied their thermal decomposition. The precipitated particles were less than a few hundred angstroms in size, and could not be easily aged. Upon heating, a considerable amount of surface water, up to n = 1 in the formula, was initially lost, followed by the ill-defined stages represented by loss of water of hydration ( n ≤ 2), first stage of dehydroxylation, loss of X (over temperature ranges between 200 and 500°C) and final dehydroxylation (up to 700°C). Interest in such possible mixed O 2−/OH −/ X − decomposition intermediates as ionic conductors is discussed.