Synthesis and characterization of C3N4 crystal (II)

Single C₃N₄ crystals with 1–3 μ in length and 300 nm in cross area was obtained on nickel substrate. The results rule out the uncertainty of the experimental lattice parameters caused by C-Si-N phase when the growth was on silicon. The X-ray diffraction and transmission electron microscopy with selective-area electron diffraction give the lattice constantsa = 0.624 nm andc = 0.236 nm for β-C₃N₄, and α=0. 638 nm andc = 0.464 8 nm for α-C₃N₄, which are respectively 2.5% and 1.3% lower than those of the latest first-principle calculations. An N:C ratio of 1.30–1.40 was determined by energy dispersive X-ray. Based on the experimental lattice constants, the bulk modulus of the obtained β-C₃N₄ are in the region of 425–445 GPa.