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作为人工预测材料,β-C_3N_4可能具有与金刚石相当的体弹性模量,并能够检验现代固体理论的预测性。 本研究首先采用离子注入、磁控溅射和微波等离子体化学气相沉积等方法,在不同基片材料和沉积温度下沉积碳氮薄膜,然后对薄膜进行成分、成键和晶体结构等方面的检测。 在成分方面,低温(<200℃)沉积薄膜的氮含量比较低,而高温(700～900℃)沉积时,氮合量有相当程度的提高;虽然在高温下硅基片上薄膜氮含量的提高不能排除氮化硅的影响,但铂基片上相当于C_4N_4成分晶态物质的获得,为β-C_3N_4的合成提供了成分上的可能。 在成键方面,低温沉积碳氮薄膜的红外吸收谱和拉曼谱中不出现与β-C_3N_4明显有关的信息;当在硅基片上高温沉积时,所得碳氮薄膜的拉曼谱中有251、302cm~(-1)峰,可能对应于β-C_3N_4,也可能对应于α-Si_3N_4。 在结构方面,硅基片上沉积碳氮薄膜与碳膜的X射线衍射谱没有明显的差别,而在石墨基体高能注氮并退火样品、铂基片上高温化学气相沉积的碳氮薄膜中,同时得到可以被解释为β-C_3N_4及其变体的X射线衍射谱,为β-C_3N_4的实际存在提供了较为可靠的证据。 总之,从室温到高温,从硅基片到石墨和铂基片,β-C_3N_4实验合成的结论逐渐明晰,为进一步的合成提供了必要的准备。
As an artificial predictive material, β-C_3N_4 may have a comparable bulk modulus of elasticity to diamond and be able to test the predictability of modern solid theory. In this study, first, carbon-nitrogen films were deposited at different substrate materials and deposition temperatures by ion implantation, magnetron sputtering and microwave plasma chemical vapor deposition. Then the composition, bonding and crystal structure of the films were measured . In terms of composition, the nitrogen content of the deposited films at low temperature (<200 ℃) is relatively low, while at high temperatures (700-900 ℃), the nitrogen content increases considerably. Although the nitrogen content of the films increases at high temperature The influence of silicon nitride can not be ruled out. However, obtaining the equivalent crystalline material of C_4N_4 on the platinum substrate provides the compositional possibility for the synthesis of β-C_3N_4. In terms of bond formation, there is no obvious correlation between β-C_3N_4 and the infrared absorption spectra and Raman spectra of low-temperature deposited carbonitride films. In the Raman spectra of the obtained carbon-nitrogen films, , 302cm ~ (-1) peak, which may correspond to β-C_3N_4, may also correspond to α-Si_3N_4. In terms of structure, there is no obvious difference in the X-ray diffraction spectrum of the carbon-nitrogen film deposited on the silicon substrate and the carbon film. In the high-energy nitrogen-nitrogen-annealed sample of the graphite substrate and the high temperature chemical vapor deposition of the carbon-nitrogen film on the platinum substrate, Can be interpreted as the X-ray diffraction spectrum of β-C_3N_4 and its variants, which provides more reliable evidence for the actual existence of β-C_3N_4. In summary, from room temperature to high temperature, the conclusion of β-C_3N_4 experimental synthesis from silicon substrate to graphite and platinum substrate becomes clear, which provides the necessary preparation for further synthesis.