The non-stoichiometry of pink zinc oxide

Abstract

A highly coloured pink zinc oxide, having a total nitrogen content of 0.054%, has been prepared by heating white zinc oxide and ammonium carbamate in an atmosphere of ammonia and carbon dioxide at 200°. The preparation results in a marked increase in the specific surface area of the zinc oxide.     The non-stoichiometry of the pink zinc oxide has been determined, and it is shown that the amount of reactive oxygen chemisorbed on the surface increases with time. The maximum chemisorption amounted to 52 p.p.m. by weight (1.1 x 10²⁵ ion m-³) after exposure for 35 days in a controlled environment. The surface concentration of interstitial zinc has been estimated indirectly from the reactive oxygen results. The concentration of the non-stoichiometric species in pink zinc oxide is more than an order higher than that of the white zinc oxide from which it was prepared. The results support the mechanism tentatively proposed by previous workers for the incorporation of nitrogen in zinc oxide.