Variation of the structure and stoichiometry of a zinc oxide ceramic in the course of sintering in an open atmosphere

Sintering of the ZnO ceramic in open atmosphere in the temperature range 200–1400$^\circ$C has been studied. The relationship is found between the processes of shrinkage and loss of mass by the ceramic, on the one hand, and changes in the structure, electrical conductivity, and luminescent characteristics, on the other. It is shown that low-temperature sintering of undoped compacted powders of zinc oxide is due to the desorption of oxygen from the surface of ZnO grains in the temperature range of 200–600$^\circ$C and to the formation of the low-melting ZnO$_{1-x}$ phase at grain boundaries, which accelerates mutual-diffusion processes. The conductivity is due to oxygen vacancies V$_{\mathrm{O}}$ for the ceramic synthesized at temperatures of up to 900$^\circ$C and to oxygen vacancies V$_{\mathrm{O}}$ and interstitial zinc Zn$_i$ for that obtained at temperatures higher than 1100$^\circ$C.