硫掺杂金刚石中杂质含量的表征与测定

本文利用扫描电镜、电子探针和波长色散X射线荧光光谱,在硫- Ni70Mn25Co5触媒-石墨粉末混合体系中,用高温高压合成法生产的金刚石,进行了全面表征,并讨论了硫对合成结果影响的原因.研究表明:硫掺杂金刚石随原料中硫含量的增加,颜色逐渐加深,金刚石表面出现孔洞缺陷,当硫含量较低时,孔洞缺陷多分布在(100)晶面上,当硫含量较高时,(111)晶面上也出现孔洞,致使晶体的完整性受到制约;杂质元素进入晶体具有晶面趋向性,Ni,Co,S杂质,特别是Mn杂质易进入金刚石的(100)晶面;金刚石中的硫杂质含量随添加剂含量的增加大致呈增加趋势,锰杂质含量呈增加趋势,而镍杂质没有十分明显的规律性.     

含硫金刚石的合成及杂质分析

本文分别用Ni70Mn25Co5合金粉末和含添加剂硫的Ni70Mn25Co5合金粉末作触媒合成了金刚石单晶，通过对比，发现添加剂硫的引入使得金刚石内的包裹体含量增加，使晶体表面出现熔坑；利用X射线荧光光谱对晶体的杂质成分、相对含量进行了分析，发现杂质元素锰、硫的含量随着触媒中硫的添加量的增加呈增加趋势，由此推测在金刚石生长过程中生成了难熔的MnS，MnS以包裹体的形式进入金刚石中，在一定程度上破坏了金刚石的晶格排列，使得表面出现熔坑。     

用含添加剂氮化物MxN的粉末触媒合成金刚石

本文分别用铁镍粉末触媒、含添加剂氮化物MxN的铁镍粉末触媒在国产六面顶压机上合成了优质金刚石单晶，利用光学显微镜观察，发现所合成的金刚石多为六八面体，晶形完整；在大多数用含添加剂氮化物的铁镍触媒合成的金刚石的晶面上有凹线出现，而用不含添加剂铁镍触媒合成的金刚石却没有这种现象。用电子显微镜对凹线的形貌进行了细致的观察。还发现用含添加剂的铁镍触媒合成的金刚石中包裹体明显少于用铁镍触媒合成的金刚石中的包裹体。随着铁基粉末触媒中添加剂氮化物含量的增加，合成金刚石的压力和温度条件逐渐增高，金刚石生长的“V形区”上移。     

FeNi-Si-C体系金刚石的成核特性

本文利用掺硅FeNi粉末触媒，在国产六面顶压机上进行了金刚石单晶的合成实验，研究了高温高压条件下，Fe—Ni—Si—C体系合成金刚石单晶的成核特性。结果表明，由于掺Si量的不同，合成金刚石的最低生长条件（压力和温度）并没有太大的改变；但随着触媒中掺Sj量的增加，其成核量也随之增加；通过光学成像显微镜观测发现，合成出的金刚石晶体同FeNi—C体系合成的晶体的颜色和形貌具有较大的区别，出现了“两极分化”现象，主要表现为部分晶体质量好，而部分晶体则质量很差（晶体呈浅黑色，晶形不完整等），且随触媒中掺甄量的增加，质量差的晶体比率增高。对不同合成条件的棒料进行X—ray检测发现，在金刚石合成条件下有FeSi和Fe，si的生成，台阶压力时间的长短直接影响FeSi、Fe3si的粒度。我们推测，难熔化合物FeSi和Fe3si参与成核，导致金刚石成核量增加，而这种金刚石的“异形核”存在，会导致晶形不够完整和包裹体的产生。     

Fe-C-S系金刚石单晶的高温高压合成

在Fe-C体系中加入单质硫(S)作为添加剂,采用高温高压法合成金刚石单晶.研究表明:S在高温高压下与Fe发生了相互作用,影响了Fe的催化性能,进而对金刚石的自发成核产生抑制作用.S的添加能使纯Fe触媒合成六八面体晶体的温度区间变宽,从而提高合成六八面体的可控性;在显微镜下观察金刚石晶体形貌颜色为深黄,晶体完整,包裹体较...     

添加剂La2O3对FeNi粉末触媒合成金刚石的影响

本文研究了添加剂La2O3对FeNi粉末触媒合成金刚石的影响。实验结果表明，La2O3对金刚石的成核具有明显的抑制作用；借助于光学显微镜，我们发现Fe—La2PO3-C体系合成出的晶体晶形完整，但透明度变的很差，且表面变得很粗糙。     

高温高压下金刚石成核机制的研究

本文以国产六面顶压机作为人造金刚石的合成设备,采用金属粉末触媒技术,进行了金刚石晶体的合成.实验中,通过对生长工艺的调整,考察了金刚石在合成区间内的不同合成习性.实验结果表明:金刚石的合成区间可以根据能否自发成核而分为成核区与生长区.在生长区内,金刚石不能自发成核,但金刚石晶种可以在此区间稳定存在并长大.在生长区内金刚...     

Fe-B-C体系金刚石单晶的高温高压制备与表征

在国产六面顶高温高压设备上,利用低价纯铁粉末为触媒开展含硼金刚石的制备研究。研究发现:无定型硼的掺入会导致金刚石合成条件(温度和压力)不断提高;晶体颜色由浅黄色逐渐变为黑色,晶体主要以八面体为主。利用扫描电镜(SEM)分析含硼金刚石的微观形貌,发现:硼添加后金刚石{111}晶面上存在微米尺寸的圆形凹坑。通过Raman光谱研究发现:随着硼掺入量的增加,金刚石特征峰发生蓝移,其半峰宽变大、晶体质量下降。通过红外光谱可以发现较强的Ⅱb型金刚石存在2 800 cm-1处的 B-C键特征峰。在纯铁触媒体系中,硼的质量分数在0.2%～0.8%时,均能合成出优质含硼金刚石。      

铁基粉末触媒的粒度及其均匀性对合成金刚石的影响

本文利用铁基粉末触媒在国产六面顶压机上进行了金刚石单晶的合成。研究了高温高压条件下（5.7GPa，1370～1650℃），筛分的6种不同粒度（140／170，170／200，200／230，230／270，270／325，325／400）以及未经筛分的混合粒度的铁基粉末触媒生长金刚石的形貌特征。同时研究了粉末触媒粒度均匀性对合成金刚石的影响。结果表明，触媒粒度越均匀，合成金刚石单晶的粒度越集中。触媒粒度以及合成的金刚石晶体分别通过扫描电镜和光学显微镜进行了观测。     

用含添加剂硫的粉末触媒合成金刚石

本文分别用铁镍触媒、含添加剂硫的铁镍触媒在国产六面顶压机上合成了优质金刚石单晶，利用光学显微镜观察，发现所合成的金刚石多为六八面体，晶形完整；在大多数用含添加剂硫的铁镍触媒合成的金刚石的{100}面，有熔坑出现，而用铁镍触媒合成的金刚石没有这种现象；用电子显微镜对熔坑的形貌进行了细致的观察。另外，还发现用含添加剂硫的铁镍触媒合成的金刚石中的包裹体要明显少于用铁镍触媒合成的金刚石中的包裹体。     

Synthesis of large diamond crystals with C3H8N4O2 as organic additive under HPHT conditions

Diamond crystals were successfully synthesized in a NiMnCo-C system by adding Malonic acid dihydrazide (C₃H₈N₄O₂) as an organic additive. The synthesized conditions in a series of experiments were about at 1300 °C–1400 °C and 6.0 GPa–7.0 GPa. The color, morphology, and inclusions of the synthetic diamond crystals were characterized by optical microscopy, Fourier transform infrared (FTIR) spectroscope and Raman spectroscope, respectively. The color of the synthesized diamonds changes from light yellow to green with increasing amounts of C₃H₈N₄O₂. The morphology of the synthesized diamonds exhibited triangular shape with abundant {111} faces. The FTIR spectra indicated that the nitrogen concentration increased whereas the hydrogen and oxygen concentration decreased with increasing concentration of the C₃H₈N₄O₂ additive. The Raman peak positions exhibited a systematic downshift with increasing amounts of C₃H₈N₄O₂ additive. According to the synthesized resultant, with increased the content of the C₃H₈N₄O₂ additive, the quality of synthesized diamond gets worse. It is interesting that the diamond content more nitrogen and less hydrogen and oxygen with increasing the C₃H₈N₄O₂ additive. By studying the effects of nitrogen, hydrogen and oxygen coexistence on the synthesis of diamond, it is would to speculate that the natural diamond nucleation and growth environment may be content more nitrogen source and less hydrogen and oxygen.     

Understanding of the shape-controlled synthesis of strip shape diamond under high pressure and high temperature conditions

We present the shape-controlled synthesis of strip shape diamond with stretched crystal faces along {100} or {111} direction and larger length-to-radius ratio than the conventional diamond in the designed NiFe-C system at high pressures and high temperatures (HPHT). A series of synthetic experimental results on the strip shape diamonds were obtained at different pressures and temperatures. Under the constant pressure condition, the morphology of the strip shape diamond varied with the increase of temperature obviously. Fourier transform infrared (FTIR) micro spectroscopy and Raman spectroscopy revealed that the various locations of crystal face have different nitrogen impurity concentration, and internal strain and defects in these strip shape crystals. According to these results, it can be concluded that the difference of growth rates at various crystal faces results in different crystal morphologies. Based on the growth characteristics, we suggest that composition segregation of the metal film around the growing crystal induces the formation of strip shape diamond.     

Effects of carbonyl nickel powders on {100}-oriented single diamond under high pressure and high temperature

In this paper, perfect {100}-oriented single diamonds with higher nitrogen concentration are successfully synthesized at a pressure of 5.5 GPa and temperature ranging from 1285 to 1294 °C by the adjustment of catalyst (Fe₆₄Ni₃₆) components. The content of carbonyl nickel powders has significant effect on the nitrogen concentration and the growth rate of the diamond crystals. Fourier transform infrared (FTIR) measurements reveal that the value of nitrogen concentration for the synthesized diamond is up to approximately 1020 ppm. Furthermore, basing on the diamond surface configuration, the structure of growth steps arranged layer by layer on {111} face is noticed using scanning electron microscopy (SEM), whereas the occurrence is not observed on {100} face.     

真空钎焊热损伤控制工艺对磨料冲击韧性的影响

为减轻钎焊单层金刚石工具中的磨料热损伤,从钎焊金刚石的热损伤机理出发,提出4种热损伤控制方案,并进行试验验证。通过SEM观察和磨料冲击韧性测试对各方案的可行性进行分析。结果表明:降低炉内氧含量的工艺对常温冲击韧性TI值提升效果不明显;降低钎料触媒元素比例和使用Ti-Ni复合镀层金刚石,TI值相比原工艺最多可分别增加15%和20%以上;铜基钎料对金刚石热损伤最小,钎焊后磨料冲击韧性可达原料值的91.5%。      

The effect of phosphorus and nitrogen co-doped on the synthesis of diamond at high pressure and high temperature

The synthesis of phosphorus and nitrogen co-doped diamond is investigated in the NiMnCo–C system by adding P₃N₅ or carbonyl iron powders mixed with phosphorus powders under high pressure and high temperature. Experimental results show that the color distribution in diamond crystals with low concentration of P₃N₅ additive is not uniform. The color becomes deep green with the increase of P₃N₅ additive. The optical images and FTIR spectra reveal that the nitrogen atoms are more easily incorporated via {111} than {100} in the same conditions. In addition, the result of FTIR spectra of synthesized diamond indicates that the hydrogen atoms in the form of sp³–CH₂– are more likely to enter the diamond lattice in the P/N co-doped system, compared with the single N-doped system. The absorption peak at 3107 cm^− 1 attributed to vibration of H-related point defects (sp²–CHCH–) is observed in diamonds, which is often found in natural diamonds. The Raman shifting to lower frequency and FWHM value becoming wider are due to the doping of phosphorus atoms.     

Synthesis and characterization of IIa-type S-doped diamond in FeNi catalyst under high pressure and high temperature conditions

In this work, service through nitrogen getter we have successfully synthesized sulfur(S) doped IIa-type diamond single crystals at 1400 °C and 5.5 GPa in FeNi-C system. We found that the synthetic diamond are mainly composited of the {111} faces because of the addition of S in the synthesis system. In addition, the color of our produced diamond changed from white to light brown and the shape of diamond changed from Cub-Octahedron to Octahedron with increase of S addition in the FeNi-C system. Furthermore, we notice that many kinds of defects, such as stratiform defects, craters and inverted pyramid defects appeared on the surfaces of diamonds induced by the additive of S. The FTIR results show that the obtained diamond crystals are IIa-type diamonds, containing less than 1 ppm nitrogen. XPS measurement indicates that S was successfully incorporated into our produced diamond lattice in the SC and CSO forms. Raman spectra reveal that the as-growth S-doped IIa-type diamond single crystals possess a high-quality sp³ structure. Photoluminescence (PL) spectra demonstrate that nitrogen-vacancy is formed during diamond growth. Our work also helpful for understanding the formation of nature diamond.     

无氢气氛下铁对金刚石的刻蚀

用铁粉在无流动氢气气氛下催化刻蚀金刚石。用扫描电子显微镜(SEM)、激光探针分析仪以及X射线衍射仪表征其表面形貌、刻蚀坑深度和刻蚀后金刚石的结构和成分,同时对金刚石的刻蚀行为进行分析。结果表明:在无氢气气氛下,铁粉通过其催化作用刻蚀金刚石晶体;刻蚀主要在金刚石的{111}、{100}面进行,且{100}面的刻蚀速率大于{111}面的,其刻蚀机制是通过铁-金刚石间形成Fe-C相实现的;且刻蚀受铁相含量影响,刻蚀后金刚石结构不变。