摘要:
利用温度梯度法,在6.2—6.4 GPa,1270—1400?C条件下,通过在NiMnCo-C体系中添加不同比例的锌粉成功合成出3 mm左右的大尺寸金刚石单晶.研究了锌添加对金刚石颜色、形貌、内部氮杂质以及晶体结晶度的影响.结果表明：随着锌添加量逐渐增加,晶体的颜色逐渐变浅,晶体的透光性增强；当锌添加比例达到3 wt.%时,晶体表面出现大量不规则的凹坑；晶体内氮杂质主要以C心形式存在,随着锌添加量的增多晶体内氮含量逐渐降低,基于锌的除氮能力总结出两种可能的除氮机制；拉曼光谱测试结果表明,在锌添加量小于3.0 wt.%的研究范围内,锌的添加有利于提高晶体的结晶度.本研究不仅有助于天然金刚石形成机制的探究,而且对丰富金刚石的种类以及扩展人工合成金刚石的应用领域都有着重要意义.
Abstract:
The large single crystal diamonds are successfully synthesized in a NiMnCo-C system with the zinc additive in a series of the experiments at temperatures of 1270–1400 ?C and pressures of 6.2–6.4 GPa by the temperature gradient growth. Morphology and structural properties of the synthesized diamond are characterized by optical microscope and scanning electron microscopy. The Raman spectrum is used to investigate the crystallization of synthesized diamond. The results show that the colors of synthetic diamond crystals change from yellow to light yellow and nearly disappears with the increase of the zinc additive. There are a large number of irregular pits in the surface of diamond crystal when the zinc additive is increased up to 3.0 wt.%. the Fourier transform infrared spectroscopy spectra reveal that the nitrogen impurity in the synthetic diamond crystal is predominantly in the form of C center (single substitutional nitrogen atoms), and the nitrogen concentration decreases with the increase of zinc additive. Two possibilities that the zinc powders can be used as the nitrogen getter are given. the Raman spectrum shows that the diamond crystallization can be improved when the zinc additive is less than 3.0 wt.%. We believe that our work is greatly helpful for deeply understanding the natural diamond genesis, enriching the types of diamonds, and expanding the application areas of synthetic diamond.
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