Carbothermal nitridation of solution synthesised ZrO2–carbon nanocomposites; phase-development from precursor to nitride

A carbothermal nitridation route to nanophase ZrN1-xCx powder using nitrogen gas and a highly homogeneous solution derived carbon-ZrO2 nanocomposite is described. Composites with 2–4 nm sized ZrO2 particles were prepared by hydrolysis of Zr(OPrn)4 and sucrose with 2–8 sucrose-C:Zr and heating to 600 °C. The phase-evolution on heating was elucidated in detail using: TG-DTA, XRD, XPS, IR- and Raman spectroscopy, SEM-EDS, and TEM-EDS. With 5–8 C:Zr samples heated to 1495 °C, somewhat agglomerated single-crystalline Zr(N,C) particles in sizes centred around 40–90 nm were obtained, in some cases with minor amounts of r-Zr7O8N4 and m-ZrO2. The c-Zr(N,C) had slightly larger XRD cell-dimensions (a = 4.589–4.606 Å) than the literature ZrN (a = 4.5775 Å), due to some carbon substitution in the nitrogen positions. The single-crystalline Zr(N,C) particle cores of the 8C:Zr, and to some extent 7C:Zr, samples, had a 4–6 nm thick distinctive amorphous or micro-crystalline Zr(N,C,O) shell.