Synthesis and Control of Nano-Scale CN Particles and its Distributions
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0942-W11-07
Synthesis and Control of Nano-Scale CN Particles and its Distributions Peter x. Feng1, and Y. C. Shi2 1 Physics Department, UPR-RP, PO Box 23343, San Juan, PR, 00931, Puerto Rico 2 Physics Department, Dong Hua University, Shanghai, Shanghai, 20051, China, People's Republic of
Abstract
Micro-scale to nano-scale carbon nitride (CN) particles were prepared by using plasma sputtering deposition techniques. The preferred orientation of nanoscale CN particle distributions was obtained. Particles were examined by using both Scanning Electron Microscopy (SEM) and Raman scattering spectroscopy. Setting bias voltage up to 5 kV, plasma-sputtering deposition yielded several rings (diameters: 2.4, 3.2, and 4.4 mm) patterns of particle distributions where many small groups of nanoscale particles were observed. Each group of these particles appeared with a sunflower type of distribution, in which the biggest (85 nm) particle at the center was surrounded by many small sizes (30 nm) of CN particles. Disk type of the particles with a diameter of 10 µm was also observed at different experimental conditions. Typical G, D bands and C=N band in the Raman spectra of the samples were identified. The intensity of the D bands obviously varied at the different deposition conditions. Keywords: sputtering deposition, nanoscale CN particles, orientation
1. Introduction Carbon nitride materials first came to the notice of most researchers through the published work of Liu and Cohen.[1,2] They predicted that the cubic β-C3N4 form of nanostructured carbon nitride film might be as hard as or harder than diamond. This led to a flurry of attempts to produce this elusive material that continues even today. We are among those who have tried to deposit cubic β-C3N4, and like most researchers, we found it difficult to do. However, CNx, where x is around 0.2-0.3, was found to be a very interesting hard material. Maximal hardness up to 40 GPa has been obtained. [3,4] Normally, most hard materials are very brittle, but CNx films are very elastic. [4] This has encouraged several recent experimental studies at both fundamental level, and application purpose. [5-8] For example, Bertran[7] studied hard CN coatings for mechanical applications. Fu [8] studied friction and wear behaviors of carbon nitride films. Amorphous carbon nitride (CNx) films were deposited on plasma nitrided Ti–6Al–4V substrate for improving the adhesion strength and tribological behaviors. Besides growth and characterization of CNx thin films above, an important research is to design and fabricate nanoscale particles, and achieve the preferred orientation of nanoscale CN particle distributions. RF plasma CVD technique, [9] microwave plasma CVD techniques, [10] plasma sputtering deposition [11] and Spark discharge and high-speed impact treatment [12] have been used in plasma processing of nanoscale CN particles. Reviews of the friction, wear and lubrication of carbon nitride particles has recently been given by Kato. [13] It is found that most of the obtained nanoscale partic
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