Observation of crystalline C3 N4

We present strong experimental evidence suggesting that we have synthesized the \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$ phase. This is a material predicted by theory to have bulk moduli comparable to diamond. Thin films containing small crystals were deposited on Si and Ge wafers by rf diode sputtering of a pure graphite target with pure ${\mathrm{N}}_{2}$. The crystal structure of these phases was investigated using x-ray and electron-beam diffractometry as well as transmission electron microscopy. Our results indicate that the \ensuremath{\beta}-${\mathrm{C}}_{3}$${\mathrm{N}}_{4}$ particles with typical dimensions of \ensuremath{\sim}0.5 \ensuremath{\mu}m are embedded in a 1-\ensuremath{\mu}m-thick layer of a C-N polymer. These particles are believed to crystallize preferentially on Si (100) wafers.