CHROMIUM NITRIDES (CRN, CR2N) FROM SOLID-STATE METATHESIS REACTIONS -EFFECTS OF DILUTION AND NITRIDING REAGENT

The solid state metathesis (SSM) reaction of CrCl3 with Li3N in a seal ed evacuated Pyrex ampoule at 445 degrees C produces a propagation wav e and enables phase pure Cr2N to be isolated. The SSM reaction of CrCl 2 and Mg3N2 at 350-500 degrees C with dilutant MgCl2, under similar co nditions produces single phase CrN. Reaction of chromium oxide with Li 3N at 500 degrees C produces CrN after 2 h and Cr2N after 60 h. This i s the first report of a metal nitride being formed in a SSM reaction u sing an oxide starting material. The SSM nitrides were shown to have s uperior bulk nitridation levels (combustion analysis) and equivalent m icroscopic compositions (EELS, XRD) to commercial materials. The phase s of chromium nitride produced were correlated with reaction enthalpy, dilution conditions and nitriding agent. The products were analysed b y X-ray powder diffraction, FTIR, combustion microelemental analysis, SEM/EDAX, XPS and ELNES.