Synthesis and characterization of C3N4 crystal (Ⅱ)——Growth on nickel

Single C3N4 crystals with 1-3μm 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 constants a=0.624 nm and c=0.236 nm for β-C3N4,and a=0.638 nm and c=0.464 8 nm for αC3N4,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.