Abstract:
The thermal decomposition of zinc nitrate hexahydrate in vacuo has been investigated using the technique of electron spin resonance. While the major decomposition of the nitrate ion occurs at 312°C, the presence of nitrogen peroxide can be detected throughout the temperature range 240–550°C, together with a line attributed to the N2O–4 radical. An e.s.r. line at g= 1.96 observed from 240–1000°C indicates the gradual formation of non-stoichiometric zinc oxide with increasing temperature treatment. Photo-effects using light in a spectral band peaking at 490 nm generally enhanced the g= 1.96 line, diminished the NO2 and N2O–4 spectra, but generated two new responses which are attributed to the NO3 radical and a hole associated with a zinc atom vacancy. Evidently the sample is not free of nitrogen oxides until a decomposition temperature of nearly 700°C, and remains as an imperfect zinc oxide lattice even when heated to 1000°C.
