Synthesis, structure and properties of new functional oxynitride ceramics

Abstract

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 SrTaO 2 N, crystal structure refinement suggested the short range O/N ordering and local tilting of cis-TaO 4 N 2 octahedra, resulting in its unusual large permittivity. Its dense ceramics were sintered with SrCO 3 additive and exhibited superior dielectric constant above 1 © 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, LaAl 12 (O,N) 19 :Eu showed photoluminescence emission peak splitting due to Eu 2+ site splitting to two crystallographic sites induced by the two kinds of anions in its crystal structure.

Synthesis of morphology controllable aluminum nitride by direct nitridation of γ-AlOOH in the presence of N2H4and their sintering behavior

“…Furthermore, the lowest oxygen content was owned by nest-like morphology since it had low crystallinity that could be confirmed by XRD measurement in Figure 1. Amorphous phase and low crystallinity precursors were believed to have stronger nitridation reactivity than that of high crystalline one [32].…”

Ca-assisted nitrogen-rich molecular approach for the synthesis of monodisperse tantalum oxide and (oxy)nitride nanocrystals for visible light–induced water oxidation

“…16) The molar quantities of reactants used in the synthesisTaCl 5 (Sigma Aldrich, Germany), urea (Sigma Aldrich, Germany), and CaCO 3 (Sigma Aldrich, Germany)are given in Table 1. Note that the molar ratio of urea/tantalum was kept to 5 in all the synthesis, while the ratio of Ca 2+ /urea was varied from 0.10 to 0.50.…”

Multimetallic Oxynitrides Nanoparticles for a New Generation of Photocatalysts

“…[9,10] Commons tarting materials are the single or mixed oxides, [11,12,13,14] hydroxide, [15] gel-like precursors, [16] Zn/Ga/CO 3 layered double hydroxides [17] or ammonolysis of amorphous precursors. [18] Even when urea was used as nitrogen source, the synthesis required the preparation of hydroxides, which were treated at 900 8Cu nder ammonia flow. [19] To enhance the Zn content,atopotactic transformation was employed but under dangerousr eaction conditions (ammonia in the presence of oxygen).…”

“…Common starting materials are the single or mixed oxides, hydroxide, gel‐like precursors, Zn/Ga/CO 3 layered double hydroxides or ammonolysis of amorphous precursors . Even when urea was used as nitrogen source, the synthesis required the preparation of hydroxides, which were treated at 900 °C under ammonia flow .…”