The vast colour spectrum of ternary metal oxynitride pigments

Ternary metal oxynitrides have attracted considerable attention because of their bright colouring, while oxide perovskites are usually colourless. In this report some technically relevant properties for the application of these materials as pigments, such as colour and thermal stability, have been measured. The crystal structure and phase purity of the samples were analysed by X-ray diffraction. The accurate colours were determined using a colorimeter. The selected oxynitrides possess a variety of different colours like yellow, orange, red, brown, green and black. In addition, the thermal stability of the compounds was investigated. All studied samples are stable in air, water and diluted acids at room temperature and start to decompose in air only above 400 °C. This high thermal and chemical stabilities make oxynitrides promising candidates to be employed in rubbers, thermoplastics, paints, etc. as ceramic pigments to substitute dyes, which contain toxic metals.