The recovered samples were either dark green (Ni 2+ , Mn 2+ , Co 2+ ) or almost black (Fe 2+ ), with the exception of pink Co 0.2 Zn 0.8 O and Co 0.3 Zn 0.7 O. According to SEM data, all synthesized solid solutions were dense, virtually poreless ceramics with grain sizes ranging from 1 to 10 microns.