Synthesis of Nanocrystalline Zr3N4 and Hf3N4 Powders from Metal Dialkylamides

A simple process to synthesize Zr3N4 and nitrogen-rich Hf3N4 powders via ammonolysis of metal dialkylamides, i.e. Zr(NEt2)4 and Hf(NEt2)4, at temperatures below 700 °C is presented. The obtained nitrides have a rhombohedrally distorted NaCl-type structure, which has previously been reported only for nitrogen-rich films of these nitrides. Regardless of the atmosphere (N2 and He), the Zr3N4 starts to decompose above about ∼ 650 °C and achieves the highest decomposition rate at about 900 °C, finally yielding the mononitride ZrN. Both Zr3N4 and Hf3N4 powders are nanocrystalline with the crystal size of about 2 nm.