Synthesis, structure and properties of new functional oxynitride ceramics

Novel metal oxynitrtides have been prepared by nitridation of amorphous metal oxide precursors obtained through citrate route. Their crystal structure, especially in O/N distribution and local bonding characteristics has been analyzed by using neutron diffraction, X-ray absorption and transmission electron microscopy, to investigate their electric and optical properties. In dielectric SrTaO2N, crystal structure refinement suggested the short range O/N ordering and local tilting of cis-TaO4N2 octahedra, resulting in its unusual large permittivity. Its dense ceramics were sintered with SrCO3 additive and exhibited superior dielectric constant above 1 x 10(4) at room temperature. New biphasic wurtzite and zinc-blende structure of gallium oxynitride nanowire was observed by using transmission electron microscopy. As-grown long gallium oxynitride nanowire exhibited a characteristic broad UV emission at 4.3 eV in its cathodoluminescene spectrum. New oxynitride phosphor having magnetoplumbite structure, LaAl12(O,N)(19):Eu showed photoluminescence emission peak splitting due to Eu2+ site splitting to two crystallographic sites induced by the two kinds of anions in its crystal structure. (C)2013 The Ceramic Society of Japan. All rights reserved.