On the validity of the formation of crystalline carbon nitrides, C3N4

X-ray powder diffraction patterns were simulated for five structures proposed for C3N4-i.e., beta-, alpha, defect zincblend-type and cubic C3N4 - with lattice constants and structure parameters reported in the literature. The comparison of experimental X-ray and electron diffraction patterns assigned to crystalline carbon nitrides with simulated ones has led us to conclude that no work has yet presented unambiguous evidence for the crystallization of carbon nitrides with the proposed structures. Disordered polytypic diamond has been proposed as the most probable candidate for part of the products which have hitherto been regarded as C3N4. (C) 1999 Elsevier Science S.A. All rights reserved.