超细Ni-C核-壳纳米颗粒的制备及其磁学和微波吸收性能

以乙酰酮丙镍为原料,通过金属有机物化学气相沉积,合成超细Ni-C核-壳纳米颗粒。采用XRD、Raman光谱仪、TEM和多功能物理测试系统对合成的纳米颗粒的物相、结构和磁学性能进行表征。这种超细纳米颗粒外表包覆一层厚度1~3 nm的C层,内部Ni核的平均粒径为13 nm。磁学测试表明,超细Ni-C核-壳纳米颗粒的饱和磁矩为24.5 emu/g,矫顽力为65.5 Oe,远低于直径超过20 nm的Ni-C核-壳纳米颗粒的对应值。微波吸收测试表明,超细Ni-C核-壳纳米颗粒和石蜡的混合物的最小反射损失值(RL_(min))为-48.7 d B,有效带宽(BW_(eff),RL≤-10dB)为7.4 GHz,是一种非常具有潜力的微波吸收材料。     

多孔道磁金复合纳米粒子(Fe_3O_4-Au/pSiO_2)的制备及结构表征

采用分步包覆法制备了具有多核壳结构的磁金复合纳米粒子Fe3O4-Au/pSiO2,所得纳米粒子单分散性好,粒径较均匀,平均粒径为150nm。经过表面保护刻蚀处理后,粒子包覆层呈多孔道结构,平均孔径为7.3nm。由于多孔道包覆层的存在,磁金复合纳米粒子出现了位于536nm处金的表面等离子体共振峰,表明其具有一定的光通透性。与未刻蚀纳米粒子相比,刻蚀后的多孔道纳米粒子的饱和磁化强度提高了13.3emu/g,达到49.6emu/g。     

金属Ni、Al纳米材料的制备及其表征

用爆炸法制备金属镍、铝纳米粉,对其纳米颗粒的形貌特征、成分、晶体结构等进行了实际测定,结果表明:Al的粒度分布比较窄,一般在30~80 nm,镍的粒度分布约30~100 nm。     

碳包覆CdS纳米颗粒的光学性能研究

采用水热法制备了核壳结构的碳包覆CdS纳米颗粒(CdS@C),利用X射线衍射、高分辨透射电子显微镜和光谱仪研究了碳包覆层对CdS@C的微观结构与光学性能影响.结果表明,碳包覆CdS纳米颗粒具有明显的核壳结构,内核为六方纤锌矿结构CdS,外壳为碳层.颗粒形貌主要为球形或椭球形结构,粒度均匀,分散性良好,粒径分布在20～6...     

液相还原法制备纳米Ag粉的研究

分别以聚乙烯吡咯烷酮(PVP)和一种复合物作表面保护剂、水合肼作还原剂,通过液相还原法制备出Ag粉,考察了保护剂的品种、用量以及还原条件等对所制备的Ag粉粒度及形貌的影响。结果表明:采用本试验的液相还原法,可以制备出具有纳米粒度的Ag颗粒,且复合保护剂的使用可以减小Ag颗粒的粒度;当复合保护剂与Ag离子摩尔比为1∶1时,所得的纳米Ag粉形状接近球形、平均粒度约为16nm,且粒度分布范围窄。通过控制工艺,可以获得纯度高、分散性好的纳米Ag粉。     

化学镀法制备金属铜包覆纳米碳化硅

采用化学镀法制备出金属Cu包覆SiC的复合颗粒.按照一定比例配制化学镀液,控制施镀过程中体系pH 值在12 左右,施镀时间在20min 之内,并改变装载量,制备出了不同包覆度的复合颗粒.通过XRD、扫描电镜、透射电镜和EDS 等进行研究,发现纳米SiC 表面包覆上了一层金属铜层,形成了SiC-Cu 壳核复合颗粒,金属铜粒径大约为5nm.     

非均相沉淀法制备铜包覆纳米SiO2复合粉体

采用非均相沉积法,利用Cu^＋的歧化反应,在纳米SiO2表面沉积包覆一层Cu,制备铜包覆纳米SiO2复合粉体,并研究pH值对包覆效果的影响。通过扫描电镜（SEM）、电子能谱仪（EDS）、X射线衍射仪（XRD）和透射电镜（TEM）分析复合粉体的形貌、成分和结构。结果表明：Cu包覆纳米SiO2复合颗粒分散均匀,粒径约200nm,粒内均匀分布着纳米SiO2颗粒,且被铜包覆隔离;在反应温度为50℃,pH=2～3条件下利于形成核-壳结构的复合粉体。     

低烧损ZrB_2/SiC复合粉末制备及涂层抗烧蚀性能研究

采用喷雾造粒-胶粘包覆的方法制备了一种低烧损核壳结构ZrB_2/SiC复合粉末,研究了胶粘包覆过程中不同清漆含量对粉末包覆效果的影响。结果表明清漆含量不足时细粉包覆不完全,细粉出现单独团聚的现象;清漆含量过多时,造成原始球形颗粒的粘连;当清漆含量为4.5%时,获得包覆效果良好的粉末,外层包覆完整均匀。为了研究等离子喷涂过程中核壳结构粉末SiC发生分解烧损程度,对比了分别采用核壳结构和均匀弥散结构ZrB_2/SiC复合粉末所制备涂层的微观形貌及涂层中元素分布。结果表明核壳结构粉末喷涂涂层成分均匀性良好,高熔点ZrB_2保护内层SiC,可有效减少SiC在等离子焰流中的烧损,实现涂层和粉末成分的一致性。对核壳结构复合粉末制备的涂层进行了20s的氧-乙炔火焰烧蚀试验,涂层质量烧蚀率为1.837×10~(-3)g/s,对涂层抗烧蚀机理进行了初步探讨。     

不同程序脉冲升温条件下一些纳米粉体中氧的释放行为

用程序升温脉冲红外法分析纳米粉体中氧分量,精选Cu,Fe4N,Ag,Fe,FeNi28,FeNi49,Ni,Sm2Fe17等12幅纳米粉脉冲红外法分析氧分量图谱,剖析多种纳米粉体氧分量图谱的特征,分别给出以吸附氧和氧化物为主峰的典型图谱,解释了氧释放行为;对比分析4幅Fe-Ni纳米合金粉的氧分量图谱,表明合金特性介于母金属之间。从高能球磨法制备Sm2Fe17纳米磁性材料过程氧图谱的变化观察氧分量的变化趋势。     

多层级NaHoF4纳米核壳颗粒的制备及其抗癌诊疗

为能够在无Ce掺杂时增强NaHoF4的荧光发射能力,设计制备了Yb3+浓度梯度多层级纳米核壳颗粒,并对其微观形貌、荧光发射能力、相结构及抗癌诊疗效果进行了测试。结果表明,合成的六边形NaHoF4颗粒结晶度良好,尺寸约为20 nm;多层级包覆壳层薄且均匀,该结构的荧光发射强度高于无/单一壳层包覆。980 nm激光照射下,表面修饰Ce6的多层级NaHoF4纳米核壳颗粒在HeLa癌细胞中具有良好的抗癌诊疗作用。     

Ag/AgCl复合粉末的制备及光催化性能研究

AgCl光催化剂可以有效避免纳米TiO_2只对紫外光响应造成的缺陷和不足。围绕Ag/AgCl复合粉体的制备及其对催化降解有机污染物的性能进行研究,采用四种不同的方法制备了Ag/AgCl复合粉体,在波长λ420 nm的可见光下考察了Ag/AgCl复合粉体对甲基橙的降解能力,并探讨了其催化机理。结果发现,催化剂的活性与复合粉体样品的形貌结构有很大关联。以AgNO_3作为Ag源,利用乙醇将部分AgNO_3还原为纳米银颗粒,并利用聚乙烯吡咯烷酮(PVP)作为高分子保护剂制备出的Ag/AgCl复合粉体表现出良好的可见光催化活性和稳定性,在20 min内几乎将甲基橙完全降解,该光催化剂对甲基橙的一级降解反应常数为4.99×10~(-2)。     

Complexation-Coprecipitation Synthesis and Characterization of Erbium and Antimony Doped SnO2 Conductive Nanoparticles

Er was used as a dopant for the first time in preparing conductive powder to improve its performance. Er and Sb doped SnO₂ conductive nanoparticles were prepared by the complexation-coprecipitation method with Sn, Sb₂O₃ and Er₂O₃ as the raw materials. Thermal behavior, crystal phase, and structure of the prepared conductive nanoparticles were characterized by TG/DSC, FTIR, XRD and TEM techniques, respectively. The resistivity of the prepared conductive nanoparticles was 0.29 Ω·cm; TG/DSC curves showed that the precursors lost weight completely before 750 °C; FTIR spectrum showed that the vibration peak were wide peak in 711 × 600 cm⁻¹; the Er and Sb doped SnO₂ conductive nanoparticles had intense absorption in 4000 × 1600 cm⁻¹; Er and Sb doped SnO₂ had a structure of tetragonal rutile; complex doping was achieved well by complexation-coprecipitation method and was recognized as replacement doping or caulking doping; TME showed that the particles were weakly agglomerated, the size of the particles calcined at 800 °C ranged approximately from 10 to 30 nm.     

Composite material based on nanocrystalline SiC reinforced with continuous SiC fibers

A paste of nanocrystalline particles was obtained by magnetron sputtering of a target consisting of silicon and graphite powders. The target and a silico-organic oil were evaporated together. Model specimens were fabricated from the paste and continuous SiC fibers. Interaction between the fibers and nanoparticles was investigated by measuring the internal friction of the model composite materials. It was found that sintering occurs in 16–20 h at 1473–1500 K for pastes containing nanoparticles with a diameter of =2–4 nm, and in 60–100 h for pastes with diameter =6–10 nm. The sinterng temperature is 230–270 K below the degradation temperature of the fibers. It was shown that it is possible to manufacture a composite material consisting of a nanocrystalline SiC matric reinforced with continuous SiC fibers. The bend strength of the composite was σ _B = (73 ± 9)·10⁷ Pat at 1500 K, and (64±12)·10⁷ Pa after thermal cycling at 1500 K for 100 h. Materials Science Institute, Ukrainian Academy of Sciences, Kiev. Translated from Poroshkovaya Metallurgiya, Nos. 5/6(395), pp. 69–75, May–June, 1997.     

Synthesis,phase study and magnetic characterisation of Co50Fe40Cu10 ternary alloy nanopowders prepared by mechanochemical alloying process

Abstract

Mechanical milling and hydrogen reduction of pure oxide mixture and magnetic characterisation of Co–Fe–Cu ternary alloy nanopowders were investigated. A powder mixture of Co₃O₄, CuO and Fe₂O₃ with Co₅₀Fe₄₀Cu₁₀ stoichiometry was first milled by a high energy planetary ball mill and then reduced in a hydrogen reduction system.

The optimum condition of the reduction under the hydrogen atmosphere was 650°C and 1 h. The X-ray diffraction patterns exhibit that the powder has ordered bcc structure with b2–bcc space group and 2·87 Å lattice parameter. Mean crystallite sizes calculated from X-ray diffraction results and mean particle size observed from electron microscopes were over 75 nm. Magnetic evaluation of ternary alloy nanopowders showed a saturation magnetisation value about 143 Am² kg^–1 and a low coercivity value of 0·93 Am^–1.     

氧化钨单晶纳米带和纳米线的气相合成

利用W纳米粉和Ni(NO3).26H2O的高温反应,可制备出长度超过20μm,宽度在200～2000nm,厚度在50 nm以下的氧化钨纳米带和长度在20μm以上,直径在100nm以下的氧化钨纳米线。合成的纳米带和纳米线均排列成放射式花状结构。XRD,SEM,TEM和EDS等一系列分析表征结果表明,合成的氧化钨纳米带和纳米线是沿<010>方向生长的,具有完好单晶结构的W18O49相。化学反应热力学分析与计算结果表明,合成的氧化钨纳米带和纳米线是通过气相沉积的方式形成的。     

约束弧等离子体制备铝纳米粉体的研究

利用自行研制的约束弧等离子体制备金属纳米粉试验装置,成功制备了平均粒度为44nm的铝纳米粉体。利用X射线衍射(XRD)、BET吸附法、透射电子显微镜(TEM)和相应选区电子衍射(SAED)等测试手段对所制备样品的晶体结构、形貌、粒度及其分布、比表面积进行性能表征。试验结果表明:约束弧等离子体法制备的铝纳米粉晶体结构为fcc结构的晶态,与体材料相比晶格常数发生膨胀。比表面积为41m2.g-1,粒径范围分布在20~70nm之间,平均粒径为44nm,粒度均匀,分散性好,呈规则球形链状分布。     

纳米颗粒Ag2Te掺杂p-(Ag2Te)x(Bi0.5Sb1.5Te3)1-x的快速热压制备和热电性能表征

通过溶剂热法制备出六方相Bi2 Te3纳米粉体,采用真空封管熔炼法得到Sb掺杂的Bi0.5Sb1.5Te3合金.采用溶剂热法合成粒度为40 nm的Ag2 Te纳米粉体,并通过高能球磨工艺将其掺入Bi0.5Sb1.5Te3合金,从而得到p-(Ag2 Te)x(Bi0.5 Sb1.5 Te3)1-x合金(x为Ag2 Te摩...     

Low-temperature thermocatalytic particulate carbon decomposition via urea solution-combustion derived CeO_2 nanostructures

A facile,one-pot,urea solution combustion route was utilized to synthesize highly catalytic CeO_2 nanostructures.CeO_2 prepared under varying thermal conditions was characterized by electron microscopy,energy dispersive X-ray spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,infrared and Raman techniques.As the synthesis temperature is raised from 400 to 1000℃,the crystallite size and dspacing of nanoparticles are observed to reduce while cell parameters remain in the same range.Particle size exhibits an accession from ～20 to ～50 nm along the process.Initial CeO_2 nanoparticles are detected as a composite structure of CeO_2 and graphitic carbon nitride(g-C_3 N_4) produced by the pyrolysis of urea.Concerning the solid carbon particulate oxidation capacity,an outstanding performance is exhibited by CeO_2 synthesized at 800℃ where the oxidation onset temperature is reduced by 27% compared with the others.The superior performance is attributed to the carbon nitride-generated unique CeO_2 nanomorphology consolidating ample reactive sites and facilitated oxygen delivery for a highly efficient thermocatalytic process.Concerning atmospheric pollution mitigation,synthesis of these CeO_2 nanostructures represents a cost effective and convenient abatement technique for carbon particulates in comparison to cost-intensive,environmentally detrimental and noble-metal based techniques.     

高分子保护固相法制备纳米氧化镁

以六水氯化镁和草酸钠为原料,用聚乙二醇作保护剂,通过室温固相化学反应制备了纳米氧化镁的前驱物,真空干燥后,在500℃焙烧前驱物3 h,得到产物纳米氧化镁。采用热分析仪、红外光谱仪、X-射线粉末衍射仪和透射电镜等研究了纳米氧化镁的形成过程和结构;并考察了焙烧温度、焙烧时间和高分子用量对粒径大小的影响。结果表明:高分子保护固相法制备的纳米氧化镁为球形立方晶系结构,纯度高,粒径小,分布范围窄,分散性好,无硬团聚,平均粒径约7.8 nm;高分子保护固相法制备纳米氧化镁的适宜工艺条件为:焙烧温度500℃,焙烧时间3 h,高分子用量3 mL。