彩色金刚石中过渡金属离子的谱学研究

过渡金属镍、钴和铁是高温高压法合成金刚石的常用触媒,已有研究表明：采用镍、钴作触媒所合成的金刚石中存在镍、钴离子,部分天然金刚石含有镍离子;镍、钴离子以替代方式或间隙形式进入金刚石的晶格,并能与杂质氮形成复合体。为了探寻彩色金刚石中过渡金属离子存在的谱学标志,确定镍、钴离子在彩色金刚石中的赋存状态,文章对6颗彩色天然与合成金刚石进行了扫描电镜-能谱、显微红外光谱、光致发光谱、电子顺磁共振谱(EPR)等测试研究。结果表明天然与合成的样品都具有与镍、钴有关的发光中心与EPR结构：包括西澳的蓝灰色天然金刚石中与镍有关的884.6 nm等发光中心,以及天然变色金刚石中与钴有关的发光中心。对各种谱学测试结果的综合分析,得出样品中存在镍、钴离子并与杂质氮形成各种Ni-N或Co-N复合体的结论,其中在天然金刚石中发现钴离子在该领域研究中尚属首次。     

Temperature-dependent phonon dispersion relation in magnetic crystals

It is shown that the lattice vibration will change the exchange energy which then contributes to the temperature-dependent phonon dispersion. The observed phonon frequency softening in nickel and cobalt at high temperatures is shown partly due to this effect.     

不同催化剂热解法制备硼碳氮纳米管过程中的影响

对以钴、镍、钴/镍、钴/二茂铁、镍/二茂铁和二茂铁为催化剂高温热解法制备的硼碳氮（BCN）纳米管的结构、产率等的影响进行了分析.实验中发现催化剂在BCN纳米管的生长过程中有重要作用.高分辨率透射电子显微镜图像显示在860℃时，以镍/二茂铁、钴/二茂铁为催化剂生成的BCN纳米管具有“竹节状”结构，且管壁较薄，镍、钴或镍/钴作催化剂生成的BCN纳米管不具有明显的“竹节状”结构，管壁较厚，且粗细不均匀，而以二茂铁作催化剂没有BCN纳米管生成.在所有生成的BCN纳米管中含有催化剂颗粒.通过对生成的BCN纳米管的结 关键词： BCN纳米管 热解 催化剂 拉曼光谱     

Production of cobalt and nickel particles by hydrogen reduction

Cobalt and nickel nanoparticles were produced by hydrogen reduction reaction from cobalt or nickel chloride precursor vapour in nitrogen carrier gas. This aerosol phase method to produce nanoparticles is a scalable one-step process. Two different setups were introduced in particle production: a batch type reactor and a continuously operated reactor. Common feature in these setups was hydrogen mixing in a vertical flow reactor. The process was monitored on-line for particle mass concentration and for gas phase chemical reactions. Tapered element oscillating microbalance measured the particle mass concentration and Fourier transform infrared spectroscopy was used to monitor relevant gas phase species. The produced cobalt and nickel particles were characterised using transmission electron microscopy and x-ray diffraction. The produced cobalt and nickel particles were crystalline with cubic fcc structure. Twinning was often observed in cobalt particles while nickel particles were mostly single crystals. The cobalt particles formed typically long agglomerates. No significant neck growth between the primary particles was observed. The primary particle size for cobalt and nickel was below 100 nm.     

STRUCTURE AND MORPHOLOGY OF CARBON NANOTUBES GROWN ON ZEOLITE-SUPPORTED CATALYSTS BY CHEMICAL VAPOR DEPOSITION

The zeolite-supported catalysts were prepared in nickel and cobalt nitrate aqueous solutions by ion exchange method. After reducing these substrates by hydrogen, we grew carbon nanotubes on them by chemical vapor deposition under different conditions. The results reveal that nickel/zeolite, cobalt/zeolite and nickel+cobalt/zeolite have different optimal conditions. When nickel+cobalt/zeolite was used as the catalyst, we can get straight carbon nanotubes. The Raman spectrum of the straight nanotubes shows they have fewer defects. We propose a growth mechanism for the growth of these nanotubes.     

PAR分光光度法测定钴和镍

进行了用PAR分光光度法同时测定钴和镍的研究。在pH=5的NaAc-HAc缓冲溶液中,钴和镍可与显色剂4-(2-吡啶偶氮)间苯二酚(PAR)的溶液形成稳定的络合物,络合物的吸收光谱重叠相互干扰,经过实验确定以508.0、568.0nm作为钴(Ⅱ)、镍(Ⅱ)的测量波长,应用双波长线性回归法可同时测定。方法简单、快速、灵敏度高。     

Effect of Pressing Parameters on the Structure of Porous Materials Based on Cobalt and Nickel Powders

Porous materials with a bulk porosity of more than 68% were synthesized by powder metallurgy methods from a cobalt–nickel mixture. The effect of the ratio of nickel and cobalt powders used in the synthesis of this porous material (including cases when either nickel or cobalt alone was applied) and the conditions of their compaction on structural parameters, such as open and closed porosities and pose size, was established.     

Nickel–cobalt oxide/activated carbon composite electrodes for electrochemical capacitors

Nanostructured synthesis of nickel–cobalt oxide/activated carbon composite by adapting a co-precipitation protocol was revealed by transmission electron microscopy. X-ray diffraction analysis confirmed that nickel–cobalt oxide spinel phase was maintained in the pure and composite phases. Cyclic voltammetry, galvanostatic charge–discharge tests and ac impedance spectroscopy were employed to elucidate the electrochemical properties of the composite electrodes in 1.0 M KCl. The specific capacitance which was the sum of double-layer capacitance of the activated carbon and pseudocapacitance of the metal oxide increased with the composition of nickel–cobalt oxide before showing a decrement for heavily-loaded electrodes. Utilisation of nickel–cobalt oxide component in the composite with 50 wt. % loading displayed a capacitance value of ～59 F g^?1. The prepared composite electrodes exhibited good electrochemical stability.     

多波长线性回归分光光度法同时测定油中的铁、钴、镍

本文提出一种同时测定铁,钴,镍的新方法,即多波长线性回归分光光度法,利用铁与５－Ｂｒ－ＰＡＤＡＰ形成的络合物在７５０ｎｍ处吸收峰不受钴,镍干扰的特点,在７５０ｎｍ处于工作曲线法测定铁的含量,对于钴,镍在５５０－６００ｎｍ内采用多波长线性回归法测定。应用于合成样及油样中铁,钴,镍含量的测定,结果令人满意,回收率为９５．７％￣１０４．３％,相对标准偏差为１．４％￣３．８％。     

火焰原子吸收光谱法测定钴-镍合金镀层中的钴和镍

利用原子吸收光谱法研究了在氨基磺酸钴-镍镀液中，赫尔槽试片上不同电流密度区合金镀层中钴、镍的含量。实验表明，该方法简便，快捷，结果准确，精密度高。相对标准偏差（RSD）为0.30%-0.62%，加标回收率为97.0%-104.0%。     

爆轰合成碳包覆钴、镍磁性纳米颗粒的探索

 介绍了爆轰法合成碳包覆钴、镍纳米磁性颗粒研究的初步结果。以黑索今炸药为主体,加入钴、镍金属硝酸盐与有机碳源材料,在爆炸容器中氮气保护下用导爆管雷管引爆,成功地合成了碳包覆钴、镍纳米磁性颗粒。为了探求爆轰固体产物的形貌特征及性能,分别采用了TEM、XRD、VSM等测试手段对其进行表征。实验结果表明,爆轰产物中主要含有碳包覆纳米钴、纳米镍磁性颗粒,成球体或者椭球体,具有完好的核壳结构形貌。合成的碳包覆钴颗粒分布在30~50 nm之间,碳包覆的镍颗粒分布在25~60 nm之间,外层碳壳层主要由无定形碳和石墨构成。磁性测试表明,所得碳包金属钴、镍颗粒在室温下具有良好的软磁特性。     

Structural and optical properties of Co-doped NiO films prepared by SILAR method

In this study, transparent thin films of un-doped and Co-doped nickel oxide were deposited onto microscopic glass substrates using the successive ionic layer adsorption and reaction (SILAR) method. The effect of cobalt doping on structural, morphological and optical properties was investigated. XRD studies reveal that all the films are polycrystalline with cubic structure and exhibit (1 1 1) and (2 2 2) preferential orientations. Co is well incorporated in the host lattice without altering the structure. All films retain high transparency throughout the visible spectral regime. No significant shift in Raman spectra was observed due to the Co doping.     

硼碳氮纳米管的拉曼光谱研究

对不同温度和不同催化条件下用高温热解法制备的硼碳氮(BCN)纳米管的拉曼光谱进行了分析。随着制备温度的升高,拉曼光谱中D带和G带的强度比I_D/I_G由小变大,而后又变小,说明存在一个最佳温度,在该温度下生成的BCN纳米管中B、N元素掺杂浓度最大。不同催化剂对BCN纳米管的拉曼光谱也有影响,当以钴/二茂铁和镍/二茂铁为催化剂时的I_D/I_G值比以钴、镍和钴/镍为催化剂时大,说明这时的B、N的掺杂浓度较高,纳米管的质量较好,这与透射电子显微镜观察结果一致。     

Functionalization of ultradispersed diamond for DNA detection

Carbon nanotubes have been synthesized by catalytic chemical vapour deposition of acetylene diluted with argon using three different catalysts, namely, nickel formate, cobalt formate and ferrocene. The synthesis was carried out at 700°C in a quartz reactor for 30 minutes. Thermal analysis was carried out in order to determine the yield of the nanotube. It was found that the deposit contains 86% nanotube, with nickel-based catalyst, which was the maximum. The yield of nanotube was 71 times that of the nickel loading. The TEM images reveal helical type of nanotubes with iron catalyst while cobalt and nickel catalysts yielded straight nanotubes. This technique can be explored for the bulk production of carbon nanotube in an economic way.     

Contact improvement of carbon nanotubes via electroless nickel deposition

Individual multi-walled carbon nanotubes (CNTs) were deposited onto microelectrodes and embedded in nickel to achieve low-ohmic contact resistances. Electroless deposition of nickel onto gold/iron, palladium, and cobalt microelectrodes was used to form electrically stable bonds at the interfaces between the electrodes and CNTs. Resistance measurements showed that the contact resistances of the CNTs on gold/iron and palladium were significantly improved by nickel embedding, whereas no further improvement was found for the CNTs on cobalt. Electroless metal deposition is a parallel process providing stable electrical and mechanical contacts between CNTs and metallic microelectrodes. PACS 81.07.De     

The effect of oxidation on the structure of nickel nanoparticles

The structural properties of nickel nanoparticles which are prepared by means of DC sputtering in argon and subsequently oxidized in ambient air are reported. Ex situ structural and chemical investigations utilizing (high resolution) transmission electron microscopy and electron energy loss spectroscopy reveal that the particles consist of a metallic core surrounded by an oxide shell. The lattice constant of the nickel core is found to increase significantly with decreasing particle size. This widening of the nickel lattice is attributed to an interfacial stress that originates from the lattice mismatch between nickel and nickel oxide. Received 21 December 2000     

Raman spectra of crystalline double sulphates

Raman spectra of single crystals of K₂M(SO₄)₂ · 6 H₂O where M=Mg, Zn, Ni or Co have been recorded for the first time usingλ 2537 as the exciting radiation. The corresponding five single sulphates have also been studied. Interesting results concerning the substitution of magnesium, zinc, nickel or cobalt in the double sulphate lattice on the sulphate frequencies are observed. The lattice spectra of these double sulphates are analysed group theoretically and discussed in relation to the lattice spectra of the corresponding individual sulphates. Certain new results concerning the Raman spectra of the individual sulphates have also been obtained and in the case of CoSO₄ · 7 H₂O the spectrum has been recorded for the first time.     

催化剂对碳纳米管产率及质量的影响

本文研究了添加钴/二茂铁、镍/二茂铁、钴、镍/钴不同催化剂对高温热解法制备碳纳米管质量、产率等的影响。高分辨率透射电镜图象显示在800℃左右,镍/二茂铁、钴/二茂铁和钴催化条件下,有多壁碳纳米管生成,而用镍/钴作催化剂时,只有直径在0 5μm左右,长度十几个微米的非晶态棒状物生成。通过对生成碳纳米管的质量和产量进行比较,催化剂的催化活性满足二茂铁>钴>镍。简单分析了在碳源高温热解环境下不同金属催化剂的性能差异,并对不同催化条件下生成物的拉曼光谱进行了分析。     

Doped lithium nickel cobalt mixed oxides for the positive electrode in lithium ion batteries

Phase pure aluminium and magnesium doped lithium nickel cobalt mixed oxides Li(Ni,Co_0.1–0.2M_≤0.05)O₂ (M=Al, Mg) were synthesised in laboratory by a synthesis procedure adopted from H.C. Stark. Structural parameters were determined by Rietveld analysis of x-ray diffraction spectra. Electrochemical characterisation took place in three-electrode teflon cells and coin-type cells versus lithium metal. Thermal stability of cathodes without electrolyte was measured by DSC. For aluminium and magnesium doped lithium nickel cobalt mixed oxides Li(Ni,Co_0.1–0.2M_≤0.05)O₂ (M=Al, Mg) the layered structure is stabilised by both aluminium and magnesium. The lithium nickel disorder is decreased by cobalt and is nearly unaffected by aluminium. According to the Rietveld refinements, magnesium seems to reduce the lithium nickel disorder strongly, even though refinements are not totally reliable in this case. Initial capacity and reversibility in the first cycle are nearly unaffected by aluminium, but strongly inferred by magnesium. Both, aluminium and magnesium doping increase the cycling stability of lithium nickel cobalt mixed oxides. Increased thermal stability of charged electrodes without electrolyte by aluminium and magnesium doping seems to be due to limited delithiation. Paper presented at the 8th EuroConference on Ionics, Carvoeiro, Algarve, Portugal, Sept. 16 – 22, 2001.     

The wetting behaviour of silver on carbon, pure and carburized nickel, cobalt and molybdenum substrates

Properties such as thermal and electrical conductivity or the expansion behaviour of silver matrix composites with carbon based inclusions are strongly affected by the contact angle between carbon and silver. In order to promote wetting of carbon, insertion of metallic interlayers such as nickel, cobalt or molybdenum is a feasible approach. This paper presents contact angle measurements done with the sessile drop method on carbon substrates (glassy carbon, polycrystalline graphite) and on pure nickel, cobalt and molybdenum foils. The ability of these interlayer elements to lower the high contact angles of silver on glassy carbon (117°) and polycrystalline graphite (124°) under vacuum conditions was verified. Unlike nickel (30°) and cobalt (26°), molybdenum (107°) nevertheless was not wettable by liquid silver (at 1273 K) under vacuum conditions. ToF-SIMS was used to identify oxygen on the surface, causing higher contact angles than expected. After oxide reduction a contact angle of 18° on molybdenum was detected. Furthermore, the influence of carbon diffusion on the contact angle was investigated by gas phase carburization of the metal foils. ToF-SIMS and XRD identified dissolved carbon (Ni, Co) and carbide formation (Mo). However, only nickel and cobalt showed a slight decrease of the contact angle due to carbon uptake.