Ternary and quaternary metal nitrides: A new challenge for solid state chemistry

The crystal chemistry of ternary and quaternary phases of the systems A/AE - TE - N (A = alkali metal; AE = alkaline earth metal; TE = transition element) is predominantly characterized by the presence and formation of complex nitridometalate onions. A suitable classification of the nitrido-compounds is based on the correlation between coordination-numbers (TE), oxidation states (TE) and the specific structural characteristics of the anionic partial structures