A solvothermal reaction of anhydrous C3N3Cl3 and Li3N using benzene as the solvent has been carried out to prepare crystalline carbon nitrides successfully at 350℃ and 5—6 MPa. X-ray diffraction (XRD) indicated that...A solvothermal reaction of anhydrous C3N3Cl3 and Li3N using benzene as the solvent has been carried out to prepare crystalline carbon nitrides successfully at 350℃ and 5—6 MPa. X-ray diffraction (XRD) indicated that the major part of our brown sample was mainly composed of a-C3N4 and b-C3N4 with lattice parameters of a = 0. 65 nm, c = 0.47 nm for a-C3N4 and a = 0.644 nm, c = 0. 246 nm for b-C3N4, which match the latest ab-initio calculations quite well. The N/C ratio in the powder is about 0.66. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spec-troscopy (XPS) analyses suggested the presence of both sin-gle and double carbon-nitrogen bonds. The kinetics effects of our solvothermal reaction to prepare crystalline carbon ni-trides are also discussed chiefly.展开更多
C3N4 films have been synthesized on both Si and R substrates by microwave plasma chemical vapor deposition (MPCVD) method. X-ray spectra were calculated for single phase α-C3N4 and p-C3N4 respectively. The experiment...C3N4 films have been synthesized on both Si and R substrates by microwave plasma chemical vapor deposition (MPCVD) method. X-ray spectra were calculated for single phase α-C3N4 and p-C3N4 respectively. The experimental X-ray spectra of films deposited on both Si and R substrates showed all the strong peaks of α-C3N4 and β-C3N4 so the films are mixtures of α-C3N4 and β-C3N4. The N/C atomic ratio is in the range of 1.0-2.0. X-ray photoelectron spectroscopy (XPS) analysis indicated that the binding energy of C 1s and N 1s are 286.2 eV and 399.5 eV respectively, corresponding to polarized C-N bond. Fourier transform infrared absorption (FT-IR) and Raman spectra support the existence of C-N covalent bond in the films. Nano-indentation hardness tests showed that the bulk modulus of a film deposited on R is up to 349 GPa.展开更多
β-C<sub>3</sub>N<sub>4</sub> compound is a new hard material predicted by Liu and Cohen with theoretical calculation and so far it has not been found out in nature. In was assumed that the β-...β-C<sub>3</sub>N<sub>4</sub> compound is a new hard material predicted by Liu and Cohen with theoretical calculation and so far it has not been found out in nature. In was assumed that the β-C<sub>3</sub>N<sub>4</sub> compound would adopt the known crystal structure of β-Si<sub>3</sub>N<sub>4</sub>, which constructed a network of CN<sub>4</sub> tetrahedra linked at the corners by threefold coordinate N atoms. Thus, the atomic coordination of β-C<sub>3</sub>N<sub>4</sub> is sp<sup>3</sup> hybrids on the C atoms and sp<sup>2</sup> hybrids on the N atoms. Based on the theoretical analysis and modeling calculation, it展开更多
基金supported by the National Natural Science Foundation of China(Grant No.20171007)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.B-123).
文摘A solvothermal reaction of anhydrous C3N3Cl3 and Li3N using benzene as the solvent has been carried out to prepare crystalline carbon nitrides successfully at 350℃ and 5—6 MPa. X-ray diffraction (XRD) indicated that the major part of our brown sample was mainly composed of a-C3N4 and b-C3N4 with lattice parameters of a = 0. 65 nm, c = 0.47 nm for a-C3N4 and a = 0.644 nm, c = 0. 246 nm for b-C3N4, which match the latest ab-initio calculations quite well. The N/C ratio in the powder is about 0.66. The Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spec-troscopy (XPS) analyses suggested the presence of both sin-gle and double carbon-nitrogen bonds. The kinetics effects of our solvothermal reaction to prepare crystalline carbon ni-trides are also discussed chiefly.
基金This work was supported by the National Natural Science Foundation of China(Grant Nos.19392300,19674009),the State Kdy Laboratory of Advanced Materials at Beijing University of Science and Technolo and the Beijing Laboratory of Vacuum Physics,Chinese Aca
文摘C3N4 films have been synthesized on both Si and R substrates by microwave plasma chemical vapor deposition (MPCVD) method. X-ray spectra were calculated for single phase α-C3N4 and p-C3N4 respectively. The experimental X-ray spectra of films deposited on both Si and R substrates showed all the strong peaks of α-C3N4 and β-C3N4 so the films are mixtures of α-C3N4 and β-C3N4. The N/C atomic ratio is in the range of 1.0-2.0. X-ray photoelectron spectroscopy (XPS) analysis indicated that the binding energy of C 1s and N 1s are 286.2 eV and 399.5 eV respectively, corresponding to polarized C-N bond. Fourier transform infrared absorption (FT-IR) and Raman spectra support the existence of C-N covalent bond in the films. Nano-indentation hardness tests showed that the bulk modulus of a film deposited on R is up to 349 GPa.
基金Project supported by the National Natural Science Foundation of China and 853' Committee.
文摘β-C<sub>3</sub>N<sub>4</sub> compound is a new hard material predicted by Liu and Cohen with theoretical calculation and so far it has not been found out in nature. In was assumed that the β-C<sub>3</sub>N<sub>4</sub> compound would adopt the known crystal structure of β-Si<sub>3</sub>N<sub>4</sub>, which constructed a network of CN<sub>4</sub> tetrahedra linked at the corners by threefold coordinate N atoms. Thus, the atomic coordination of β-C<sub>3</sub>N<sub>4</sub> is sp<sup>3</sup> hybrids on the C atoms and sp<sup>2</sup> hybrids on the N atoms. Based on the theoretical analysis and modeling calculation, it
