Synthesis of Nanosized Titanium‐Chromium Oxynitride Powders by Ammonolysis of Coprecipitated TiO₂/Cr₂O₃ Precursors

Abstract

Interstitial titanium‐chromium oxynitrides in the solid solution series Ti1−zCrz(OxNy) (z= 0.2, 0.4, 0.5, 0.6, 0.8) have been obtained by ammonolysis of the TiO2/Cr2O3 precursors resulting from the coprecipitation method. The precursors and the resulting oxynitrides were characterized by auger electron spectroscopy, X‐ray diffraction analysis, electron probe microanalysis, transmission electron microscopy, and BET surface area techniques. Compounds in the Ti1−zCrz(OxNy) series are prepared as single phases by nitridation at 1073 K for 8 h. The as‐synthesized oxynitride powders contain only Ti1−zCrz(OxNy) with cubic structure and the particle size is in the nanometer scale.

Synthesis of New Nanocrystalline Titanium–Niobium Oxynitride Powders

“…It is well known that two isostructural transition‐metal nitrides may form a bimetallic solid solution, provided that their cell parameters differ by no more than about 10%–15% 10 . Based on this principle, titanium–chromium oxynitrides, 5 vanadium–chromium oxynitrides, chromium–molybdenum oxynitrides, 10 and vanadium–molybdenum oxynitrides 11 solid solution powders have been successfully prepared. According to the JCPDS database, the cell parameters of cubic NbN and cubic TiN are 4.392 Å (JCPDS 38‐1155) and 4.241 Å (JCPDS 38‐1420), respectively, whose difference is <4%.…”

“…A homogeneous mixture of metal oxides with small particle size was active and beneficial to form oxynitride solid solution by ammonolysis 5 . TiO 2 /Nb 2 O 5 composite powders prepared by coprecipitation were mixed at molecular level and had a small particle size.…”

“…Binary metal nitrides (oxynitrides) have been synthesized by several methods, including the direct reaction of a metal nitride with another metal or metal nitride, the reaction of a mechanical mixture of two metal powders with nitrogen or ammonia, the reaction between a metal amide with a metal nitride at low pressures (under flowing nitrogen or ammonia) or at high pressures (autoclave), 4 and the ammonolysis of different binary metal precursors (metal oxides, 5–8 gels, 9 freeze‐dried precursors, 10,11 ). Among these methods, ammonolysis of metal oxides is the simplest and cheapest.…”