Synthesis of carbon nitride nanocrystals on Co/Ni-covered substrate by nitrogen-atom-beam-assisted pulsed laser ablation
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Carbon nitride nanocrystals were synthesized on Co/Ni-covered Si(100) wafers using a nitrogen-atom-beam-assisted pulsed laser ablation deposition method. Transmission electron miscroscopy, x-ray diffraction, and Raman spectroscopy showed that as-deposited films were constructed primarily from nanometer-sized –C3N4 and CNx crystallites. The co-catalyzation by the cobalt and nickel in the synthesis process is considered to play an important role in the formation of nanocrystalline –C3N4. The reasons for the formation of carbon nitride nanocrystals were analyzed.
In the last decade, much effort has been focused on synthesis of carbon nitride due to its prominent characteristics and potential applications.1–12 So far, this new material has been synthesized using a variety of technologies, including plasma-assisted chemical vapor deposition,3,4 ion-beam-assisted deposition,5,6 reactive radio frequency (rf) sputtering and direct current (dc) magnetron sputtering,7–9 and laser ablation.10–12 Due to the high reactivity of atomic nitrogen, ion/atom-beamassisted pulsed laser ablation methods have been used for synthesizing carbon nitride by forming covalent carbonnitrogen bonds in the synthesized material.10–15 But in those reports, the carbon nitride films synthesized on bare silicon substrates are usually termed amorphous CNx. Only scattered –C3N4 grains embedded in the matrix of amorphous films were observed by transmission electron microscopy (TEM) and the reproducibility of the experiments were not mentioned. To promote the formation of –C3N4, a proper transition structure from substrate to sp3-bonded carbon nitride had been thought necessary.12 The synthesis of carbon nitride films on nitrided diamond coating containing sp3-bonded –C3N4 phase by atom-beam-assisted laser deposition has been reported.12 Raman spectra supported the existence of –C3N4 phase in the synthesized film. However, due to difficulty and contingency of nitridation of diamond, it is necessary to search other methods to synthesize the kind of material. Using Co as catalyst to synthesize carbon nitride films by atom-beam-assisted laser deposition has been attempted. Raman spectroscopy, x-ray diffraction pattern (XRD) and field-emission scanning electron microscopy (FESEM) showed that the synthesized films were constructed primarily from nanometer-sized –C3N4 and CNx crytallites. 2552
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J. Mater. Res., Vol. 18, No. 11, Nov 2003 Downloaded: 13 Mar 2015
In this article, we used a nitrogen-atom-beam-assisted pulsed laser-ablation deposition (PLAD) method to synthesize carbon nitride films on Co/Ni-covered substrates. With this method, a mixture of cobalt and nickel was used as a catalyst to promote the formation of –C3N4. The nitrogen atoms in the reactive nitrogen beam had an intensity of 1016–1017 atoms/sr s and average kinetic energies of 100–150 eV, not destroying the structure of the synthesized film due to their values, which were less than the diabonding energy of nitride. XRD and Raman spectroscopy were used t
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