Published online by Cambridge University Press: 03 March 2011
A microstructural characterization of the La2−xSrxNiO4+δ (0 ⋚ x ⋚ 1) system, prepared with accurate control of the oxygen content, has been performed. The electron diffraction study shows the evolution of the accommodation of compositional variations as a function of δ. For δ > 0.06, interstitial oxygens are ordered, leading to new K2NiF4 superstructural types. Samples with δ < 0.06 accommodate the nonstoichiometry by means of random distribution of anionic vacancies.