Synthesis of nickel-iron spinel by non-conventional methods

Nickel-iron black ceramic pigments of (Fe0.8Mg0.2)(Fe0.2Ni0.8Cr)O4 and (Fe0.8Mg0.1Zn0.1)(Fe0.2Ni0.8Cr)O4 compositions have been prepared by non conventional methods such as coprecipitation, microemulsion and polymeric gel routes (alkoxides hydrolysis-condensation), and compared with ceramic samples prepared by the solid state reaction from oxide precursors. The mineralising effect of a 2NaCl:NaF flux agent has been also analysed. Both non conventional methods and mineraliser presence increase the reactivity of the samples. The highest reactivity and the best black colour are obtained in the polymeric gel sample prepared from alkoxides; coprecipitated and microemulsion fired pigments are partially solubilised by glazes due to the small particle size exhibited, leading to brown colours.