Synthesis And Application On Silicon Nitride/Oxynitride Based Materials

Micro/nano materials comply with the laws of some macroscopic world, but also showsthe characteristics of the nanometer materials in different degree, is rapidly becoming thefocus of the21st century the world scientific research. Si-O-N ceramic is an important systemin ceramic materials, low dimensional structure of Si-O-N ceramic have great potentialapplication in build a nano devices and as composites phase due to its unique properties. Inthis paper, we studied the micro/nano materials with excellent mechanical properties fromthe perspective of the structural ceramics; then from a new performance of ceramic material,studied the silicon oxynitride micro/nano materials in the application of optical; and thenstudied the micro/nano materials which application in energy storage and conversion.Uniform pitch diameter and line diameter silicon nitride microsprings are prepared byCVD method and the growth behavior is deduced. Through the analysis of products atdifferent holding time, we think the growth Si3N4of microspring may divide into three stages.In the first stage, SiO gas evolves by the reaction between Si and SiO2. In phase two, Si reactswith addictives to produce FeSixand FeSixOy.The compounds are basically conglobatetogether in the form of liquid. In the third stage, SiO enters catalyst droplets to react withNH3or O2.Then the resultant consist of SiO2, Si2N2O and Si3N4grow outward from catalystdroplets under the driving force of supersaturation. With the increase of holding time duringheating, amorphous Si3N4transfers into crystalline Si3N4while SiO2and Si2N2O convertinto Si3N4. The original amorphous product with slow solidification sags down because ofgravity as it grows. Microspring or microcoil is formed under the synthetically force ofsupersaturation, gravity and the impulse of air flow. The nucleation of microspring isproceeding rapidly when reaches the right temperature. We also studied the effect of growthconditions on the microspring, and forecasts the silicon nitride process of micro/nano springgrowth.Superelastic uniform pitch diameter and line diameter silicon nitride microsprings areprepared by CVD method. The internal structure are first studied by TEM test and the siliconnitride microsprings are firstly fabricated as TEM sample by the RTO metal embeddedsections microns-nano characterization method. The special structure of fine grains and no grain boundaries make the silicon nitride microscoils possess such good superelasticproperties. From analysis of Raman spectra during the process of stretching, themicrospring’s inner structure becomes disorder and Si-N bond length becomes longer.However, these vibrations with internal vibration only exist within the primitive unit cell.Pseudomolecular structural unit and residual stress of crystal never changed during thestretching process. The special structure of fine grains and no obvious grain boundaries makethe silicon nitride microscoils possess such good superelastic properties. Superelasticmechanism of ceramic microsprings may promote the application in improving the brittlenessof the ceramic materials. The research method mentioned in this paper on the superelasticmechanism also can provide some inspiration for study other superelastic materials.Unexplored Fe doped silicon oxynitride One-dimensional fluorescence microwiresusing CVD method at ordinary pressure was reported. This kind One-dimensional materialwas low-price, non-toxic, chemical stable, and has good mechanical properties. Fluorescenceproperties of Fe doped silicon oxynitride were studied. The emission band centers invariantwith different excitation power, which shows the fluorescence of Fe doped silicon oxynitrideis very steady. Fluorescence intensity nonlinear increase with the increased excitation power,which may infer generate nonlinear laser by means of increased excitation power. Based onthe experimental results, luminescence mechanism has been studied preliminary. Accordingto the luminescence mechanism, we designed and obtained a series samples of different O/Nratios. The absorption and external quantum efficiency of Fe doped silicon oxynitride are73.2%and51.8%. The fluorescence spectra demonstrated that emission centers infrared shiftwith increasing O/N ratios. So, the emission bands can be tuned by the component. We expectFe doped silicon oxynitride microwires with tunable red-emitting can be a robust candidatefor future applications in micro solid state laser, telecommunications, biosensor and futureintegrated photonic platforms.We exploit the amorphous Ni(OH)2hollow nanoboxes precursors are produced by atemplate method. The samples have a uniform morphology, a high surface area of214.6m2g1and a mesoporous structure of4-20nm. The high specific surface area and mesoporousstructure are favorable for the pseudo-capacitance reaction and improve the electrochemicalproperties of materials. The results demonstrate the high specific capacitance and excellent cycling property of the amorphous Ni(OH)2nanoboxes material for high-performanceelectrochemical pseudocapacitors. These amorphous Ni(OH)2hollow nanoboxes show highspecific capacitance of2495,2378,2197,1993F g1at discharge current of1,2,5and10A g1respectively. After continuous charge-discharge measurements over1200cycles at acurrent density of5A g1, the specific capacitances are still maintained at about2100F g1,only losing less than5%capacitance at the end of the test.