Rapid synthesis of crystalline spinel tin nitride by a solid-state metathesis reaction

Spinel tin nitride (Sn₃N₄) was prepared by high-pressure solid-state metathesis reactions. Tin tetraiodide was reacted with lithium nitride and ammonium chloride in a piston-cylinder apparatus at 623 K and 2.5 GPa. Powder X-ray diffraction combined with Rietveld refinement confirmed the spinel structure, with a lattice constant of a = 9.0144(1) Å. Raman spectroscopy revealed five active vibrational modes at 160, 252, 416, 524, and 622 cm^-1, which are consistent with the spinel structure. Mid-infrared spectroscopy exhibited only a Sn-N stretching mode at 547 cm^-1. Transmission electron microscopy was used to reveal particle size and morphology. Electron probe microanalysis was used to verify the elemental composition.