镍纳米线的简易合成及其气敏性能(英文)

采用水热法,以聚乙二醇(PEG)作为辅助剂,通过先驱物NiC2O4·2H2O合成氧化镍纳米线,并通过SEM和XRD对样品的微观结构进行分析。实验结果显示:PEG对镍线的合成起重要作用,镍纳米线表现出良好的气敏性能。该形态使得氧化镍(NiO)可作为传感器的气敏材料得到应用。     

水热改性法制备分散性纳米氧化镍

以NiCl2 和NH4HCO3为原料, 探讨了采用常温合成-水热改性-中温焙烧工艺制备分散性纳米NiO的可行性。常温条件下制备的产物主要由NiCO3 Ni(OH)2和Ni(OH)2微晶相组成且团聚现象突出;水热改性可进一步促进沉淀的形成,降低产物中Ni(OH)2及水分含量,使后继焙烧产物(纳米NiO)的分散性得到显著改善。热力学计算表明: 在Ni2+-NH3-CO32--H2O体系中, 升高温度有利于镍氨络离子的解离, 促进NiCO3 和Ni(OH)2沉淀的形成。温度越高,形成NiCO3的热力学可能性越大。     

不同微观形貌VO2的微波水热可控合成

采用一种新颖的微波水热法制备VO2粉体,利用扫描电镜(SEM)表征所合成粉体的微观形貌,调节H2O2的浓度、微波功率、微波时间、pH值、水热反应时间及钨掺杂剂等合成工艺参数,实现了对VO2粉体形貌的调控。结果表明:控制不同的工艺参数可合成具有不同形貌如球形、空心椭球形,花簇状、棒状等VO2粉体。     

Si4+和F-掺杂对LiNi1/3Co1/3Mn1/3O2结构和电化学性能的影响

以Li2CO3、NiO、Co2O3、MnO2、LiF和SiO2为原料,采用机械力活化固相法制备了Si4+和F-掺杂的锂离子电池正极材料LiNi1/3Co 1/3Mn1/3O2.通过X射线衍射(XRD)、扫描电镜(SEM)和电化学性能测试等技术研究了LiNi1/3Co1/3Mn1/3O2的结构特征、形貌及电化学性能等.结...     

Study on Preparation Technology of Nickel Powder with Liquid Phase Reduction Method

采用液相还原法,以水合肼为还原剂,硫酸镍为原料,氢氧化钠为pH值调节剂,在不添加分散剂的情况下制备超细镍粉,并探究了体系反应温度、pH值、Ni2+离子浓度、N2H4·H2O/Ni2+摩尔比工艺参数对制备镍粉的平均粒径、形貌及分散性的影响。通过扫描电子显微镜(SEM)、X射线衍射(XED)、能谱分析、激光粒度分析等测试手段表征粉体的性质。得出了实验的较佳工艺参数:反应温度80℃、pH值为11、Ni2+离子浓度为0.5 mol/L,[N2H4·H2O]:[Ni2+]适宜范围为2~4,制得镍粉的平均粒径为400 nm。     

纳米陶瓷结合剂粉体的网络凝胶法制备与表征

采用高分子网络凝胶法(P-G法)制备了用于超精磨削用金刚石砂轮陶瓷结合剂组分。采用XRD、DSC、TEM等分析测试手段对纳米粉体的颗粒形貌、粒度大小和物相结构进行了表征。实验结果表明,应用P-G法制备单组分氧化物粉体(如Al2O3、MgO、SiO2、ZnO等),氧化物粉末易于确定煅烧温度,可以制备出物相单一、颗粒形态近球形、粒度分布窄的纳米粉体;但对于化学性质活泼的Na2O、K2O等氧化物的粉体则难以制备。     

Ni-Mo太阳光谱选择性吸收涂层的制备与性能研究

以自制Ni-Mo团聚型复合粉末为喷涂原料,采用超音速火焰喷涂法制得Ni-Mo太阳光谱选择性吸收涂层,表征了复合粉末和涂层的表面形貌,涂层的组成元素、相组成和光学性能,研究了粉末粒径大小、涂层组分比例和表面处理对涂层选择性吸收性能的影响.结果表明:当所用复合粉末粒径r≤45μm,粉末中Ni,Mo质量比为7:3时,制备的涂...     

Effect of Water Vapor on the High-Temperature Oxidation of Pure Ni

The high-temperature oxidation behavior of pure Ni in air and Ar with and without 30?vol%H₂O at 1,000?°C was investigated to understand the effects of water–vapor on the resulting oxidation kinetics and scale structures. It was found that water–vapor significantly affected the morphology and scale structure of NiO. A duplex NiO scale with a powder-like outer and dense inner NiO layer developed when the Ni was oxidized in atmospheres containing water–vapor. The grain size of the dense inner NiO layer was much smaller than that formed in dry atmospheres. The growth of the powder-like NiO required outward diffusion of Ni and its continued formation occurred at the interface between the powder and dense NiO layers. The dense inner NiO layer grew outward and incorporated the powder-like NiO particles and the resulting grain size of the inner layer was smaller in the presence of water–vapor. The water–vapor is speculated to have prevented sintering of NiO particles during growth of the NiO scale.     

Microstructural evolution of NiFe2O4-10NiO powder prepared by high temperature solid state reaction

1 Introduction The development of inert anode materials for aluminium production has gained considerable attention in recent years[1,2]. The significance of such anodes is the ability to produce environment-friendly O2 gas during electrolysis instead of g…     

Ni-Ti-O纳米片/泡沫镍复合电极的显微结构及其电化学性能

采用了水热合成和热扩渗结合的方法在三维多孔泡沫镍支架上制备了Ni-Ti-O纳米片层。通过扫描电镜（SEM）、X射线衍射（XRD）、透射电镜（TEM）、高分辨透射电镜（HRTEM）对泡沫镍支架上NiO和Ni-Ti-O纳米结构的微观形貌及物相进行了观察表征和物相分析。用循环伏安法和充放电性能测试探究了复合电极对甲醇的催化氧化性能及其电容性能。结果表明：泡沫镍上生长的Ni-Ti-O纳米片物相组成为NiO和TiO,并且为多晶形态;Ti的渗入会使得NiO纳米片中形成氧空位,并和Ni产生协同作用,使得Ni-Ti-O纳米片/泡沫镍电极的对甲醇氧化的电催化性能优于Ni(OH)2/泡沫镍和NiO/泡沫镍电极;泡沫镍和钛粉质量比（RNi/Ti）为1:24,在电流密度为5 mA?cm-2时,Ni-Ti-O电极的面积比电容值为 2.15 F?cm-2,是纳米Ni(OH)2/泡沫镍电极的3.2倍（0.67 F?cm-2）。     

SiO2-Al2O3-FeO体系中制备莫来石连续纤维

以Al2O3、SiO2、Fe2O3、Fe粉末为原料,通过熔融拉丝法制备了多晶莫来石连续纤维;通过XRD、SEM及EDS分析,讨论了莫来石纤维的形成过程及机理.结果表明,采用熔融法从SiO2-Al2O3-FeO体系中能够制备出组织形态为针状的莫来石连续纤维;含有一定玻璃相的纤维在20%的氢氟酸溶液中浸泡,烧结后能够得到莫来石质量分数较高的连续纤维.     

SiO2包覆对含微量CO氢环境中LaNi4.25Al0.75吸氢动力学性能的影响

采用气相二氧化硅法制备了LaNi4.25Al0.75/SiO2复合材料,研究了该复合材料表面形貌以及氢中微量CO对LaNi4.25Al0.75合金及LaNi4.25Al0.75/SiO2复合材料吸氢动力学性能的影响。结果表明：合金被毒化后,在表面生成含NiO、La(OH)3、La2O3、Al(OH)3的氧化层,并且吸附大量CO,导致合金的吸氢量减少,动力学变慢。表面包覆SiO2可显著改善合金抗毒化性能     

Thermodynamic analysis on preparation of fibrous NiO precursor powders with oxalate precipitation process

According to the principles of simultaneous equilibrium and mass balance, a series of thermodynamic equilibrium equations of Ni（ Ⅱ）-C2 O4^2--NH3-NH4^＋-H2O system at ambient temperature are deduced theoretically and the logarithm concentration versus pH value（lg[Ni^2＋ ]r-pH） diagrams at different solution compositions are drawn. The results show that when pH is above 8.0, nickel ions coordinate with ammonia, the precipitation proceeds slowly accompanying with the release of nickel ions from the multi-coordinated Ni（NH3）n^2＋ （n= 1, 2,…, 6） and the morphology of NiO powder precursor is fibrous; when pH is below 8.0, nickel ion directly reacts with C2O4^2- and the morphology of NiO powder precursor is of cubic-shape. Some experiments were made to confirm the relation between the total concentration of nickel ion and pH. It is shown that the thermodynamic mathematical model is correct and the calculated values are basically accurate.     

Facile synthesis of NiO nanowires and their gas sensing performance

The NiO nanowires were prepared by a facile PEG assisted hydrothermal method using NiC₂O₄·2H₂O as a precursor compound. The microstructure of the samples was characterized by SEM and XRD. The gas sensing properties of the NiO nanowires toward ethanol was also investigated. The results show that PEG plays a key role in the synthesis of wire-like NiO. The NiO nanowires show excellent sensing performances to ethanol gas. This morphology holds substantial promise for applying NiO as a potential gas sensing material for future sensor application.     

The effect of NiO catalyst on reduction,synthesis and binder content of TiC-Ni nanocomposite

In the present study, synthesis of TiC-Ni nanocomposite via magnesiothermic method was investigated. The effects of catalyst content on the mechanisms of TiO₂ reduction and synthesis of TiC-Ni nanocomposite were evaluated. For this purpose, the powder mixture was milled at different NiO content. By adding 0.1–0.3 at.% NiO to the mixture and milling after combustion, it was found that the synthesis did not completely occur. In 0.4 at.% NiO to the mixture, the synthesis was completed and after leaching pure TiC was synthesis. Additionally, the effect of NiO on the binder content composite synthesis was examined. It was observed by increasing NiO content, combustion time decreased and Ni content in nanocomposite increased. TEM observations confirmed for 0.4 at.% NiO at initial powder pour TiC with spherical morphology and for >0.5 at.% NiO at initial powder TiC-Ni nanocomposite with semi- spherical morphology was synthesis.     

Generation of nanocrystalline NiO particles by solution combustion method and its Zn?NiO composite coating for corrosion protection

The nanocrystalline nickel oxide (NiO) particles have been successfully prepared by a simple, fast, economical, and eco‐friendly solution‐combustion method using Ni(NO₃)₂ · 6H₂O (oxidizer) and sugar (dextrose as fuel). The as‐prepared compound was calcined for an hour at different temperatures. The synthesized NiO was characterized by XRD, TGA, SEM/EDX, TEM, XPS, FT‐IR, and UV–Vis spectral methods. The crystallite sizes of the NiO particles were measured. Rietveld refinement of X‐ray data matches the cubic structure with space group of Fm3m (No. 225). The thermal behavior of as‐prepared compound was examined. Scanning electron micrographs show uniform cubic like morphology of NiO and its chemical composition was measured. The TEM results reveal that the particle sizes were in the order of 70–80 nm. The red shift was noticed in UV–Vis absorption spectra. As an application part the Zn? NiO composite coating was prepared by electrodeposition method and its corrosion behavior was analyzed by Tafel, impedance and anodic polarization in aggressive medium.     

INTERFACE REACTION IN MAGNETIC MULTILAYERS

1. Introduction"Exchange bias" [1], which refers to a shift (He. ) in the magnetization curve away fromthe zero field axis is an important phenomenon observed when a ferromagnet (FM) is incontact with an antiferromagnet (AF). Despite four decades of researcIl since its discovery,an understanding of this effect has still not been established. In recent years, the exchangecoupling between ferromagnetic (FM) and antiferromagnetic (AF) thin filIns has receivedincreasing attention in physics be…     

柠檬酸法制备热障涂层用La2Ce2O7粉体

以ZrO(NO3)2·2H2O、Ce(NO3)·6H2O和La2O3为原料,采用柠檬酸法制备了La2Ce2O7粉体,研究了pH值、乙二醇及柠檬酸用量、煅烧温度等工艺参数对La2Ce2O7粉体的影响。结果表明,采用该方法能够制备纯净的La2Ce2O7粉体,最佳实验条件是pH值为5,乙二醇、柠檬酸与金属离子的摩尔比分别是1.8和2,煅烧温度为400℃。     

Effect of adding methods of metallic phase on microstructure and thermal shock resistance of Ni/（90NiFe2O4-10NiO） cermets

Ball mixing and electroless plating were respectively used as the adding methods of metallic phase to prepare Ni/（90NiFe2O4-10NiO） cermets for the inert anode in aluminum electrolysis. The microstructure and thermal shock resistance of cermet samples were studied. The results show that, for the samples prepared by ball mixing method, aggregation of metallic phase is found in either the green blocks or sintered samples and the extent of aggregation increases with the increase of metal content. For 6.5Ni/（90NiFe2O4-10NiO） cermets prepared with electroless plating method, the homogeneous and fine metallic particles are found in either the green compacts or sintered samples, but the relative density and thermal shock residual strength decrease by 3% and 28%-58% respectively, compared with samples prepared with ball mixing method.     

Preparation of Li[Ni1/3Co1/3Mn1/3]O2 powders for cathode material in secondary battery by solid-state method

Employing Li2CO3, NiO, Co3O4, and MnCO3 powders as starting materials, Li[Ni1/3Co1/3Mn1/3]O2 was synthesized by solid-state reaction method.Various grinding aids were applied during milling in order to optimize the synthesis process.After successive heat treatments at 650 and 950 ℃, the prepared powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscopy, and transmission electron microscopy.The powders prepared by adding salt (NaCl) as grinding aid exhibit a clear R3m layer structure.The powders by other grinding aids like heptane show some impurity peaks in the XRD pattern.The former powders show a uniform particle size distribution of less than 1 μm average size while the latter shows a wide distribution ranging from 1 to 10 μm.Energy dispersive X-ray (EDX) analysiss show that the ratio of Ni, Co, and Mn content in the powder is approximately 1/3, 1/3, and 1/3, respecively.The EDX data indicate no incorporation of sodium or chlorine into the powders.Charge-discharge tests gave an initial discharge capacity of 160 mAh·g-1 for the powders with NaCl addition while 70 mAh·g-1 for the powders with heptane.