溶液燃烧法合成纳米ZnFe2O4晶体

采用溶液燃烧法合成了ZnFe₂O₄纳米晶体,系统考察了不同燃料,燃料/氧化剂的摩尔比对ZnFe₂O₄晶相组成和形貌的影响。采用XRD和SEM对产物的晶相组成、晶粒大小、晶体形貌以及表面形态进行了表征。结果表明:燃料种类和燃料/氧化剂比对合成产物晶相组成影响显著。以丙氨酸和甘氨酸为燃料合成所得的纳米晶相较好;以丙氨酸和甘氨酸为燃料时,都是在贫燃（—50%）时得到最好ZnFe₂O₄纳米晶型,尺寸分别为34.4nm和29.7nm。     

基于Al2O3/Pt纳米晶/HfO2叠层的MOS电容存储效应研究

采用电子束蒸发Pt和后快速热退火的方法,研究了退火条件对Pt纳米晶的生长特性的影响,结果显示Pt纳米晶的密度随退火温度的升高和退火时间的延长均表现出先增大后减小的趋势.在800℃下退火20 s能得到分布均匀的、密度为30×10¹¹ cm^-2的Pt纳米晶.进一步研究了基于Al₂O₃/Pt纳米晶/HfO₂叠层的MOS电容结构的存储效应,表明其在-3—+8 V扫描电压范围下C-V< 关键词： Pt纳米晶 快速热退火 原子层淀积 存储效应     

FeS2多晶薄膜电子结构的实验研究

用磁控溅射方法制各纯Fe薄膜，并硫化合成FeS₂. 采用同步辐射X射线近边吸收谱与X射线光电子能谱研究了薄膜的电子结构. 结果表明，合成的FeS₂薄膜，在费米能级附近，有较强的Fe 3d态密度存在，同时，在价带谱中2—10eV处有强度较大的S 3p态密度存在；Fe的3d轨道在八面体配位场作用下分别为t_2g和e_g轨道，实验中由Fe的吸收谱计算得到两分裂能级之差为2.1eV;实验测得FeS₂价带结构中导带宽度约为2.4eV，导带上方仍存在第二能隙，其宽度约为2.8eV. 关键词： 磁控溅射 二硫化铁 X射线吸收近边结构 电子结构     

非晶Fe73.5Cu1Nb3Si13.5B9合金激光纳米化的超精细结构研究

在CO₂激光功率为50—300W、扫描速度为20mm/s、激光散光斑为20mm照射条件下 ，诱导非 晶Fe_735Cu₁Nb₃Si_135B9带中发生结构重组，产生定量纳米α-F e(Si)晶相形成双相组织结构材料. 利用穆斯堡尔谱研究了非晶Fe_735C u₁Nb₃Si_135B₉合金激光纳米化的 超精细结构. 实验结果表明，激光诱导非晶 Fe_735Cu₁Nb₃Si_135B ₉纳米化后，其超精细磁场的分布随 着激光功率变 化由单峰向双峰变化，在高功率辐照时， 出现了双峰分布，并且峰位向高场移动. 高激光 功率辐照非晶Fe_735Cu₁Nb₃Si_{135B9合金纳米晶化相有四种超精细结 构，即2个超精细磁场较小的初晶相和2个超精细磁场较大的纳米晶化相. 其中超精细磁场较 大(17—25MA/m)的α-Fe(Si)相为DO3结构. 关键词： 激光 纳米晶α-Fe（Si) 735}Cu₁Nb< sub>3Si_135B₉')" href="#">非晶Fe_735Cu₁Nb< sub>3Si_135B₉ 超精细结构 超精细磁场     

Y2O3:Eu纳米晶中能量传递相互作用的研究

通过浓度猝灭曲线确定了引起Y₂O₃纳米晶中Eu³⁺发光浓度猝灭的是交换相互作用.测量了两种颗粒尺寸下Eu³⁺的⁵D₀—⁷F₂跃迁发光衰减曲线随掺杂浓度的变化,利用交换相互作用的理论衰减曲线对实验衰减曲线进行拟合.计算Eu³⁺离子的交换相互作用能量传递的效率,分析了Y₂O_{3关键词： 能量传递 2}O₃Eu纳米晶')" href="#">Y₂O₃Eu纳米晶 发光衰减     

纳米La2(MoO4)3∶Eu/Fe3O4磁性荧光粉末的制备及用于指纹显现的研究

采用水热法和共沉淀法分别合成了纳米La₂(MoO₄)₃∶Eu荧光材料和纳米Fe₃O₄磁性材料,并利用透射电子显微镜、X射线衍射仪、荧光光谱仪表征纳米材料的形貌尺寸、晶体结构、荧光性能。经表征,纳米La₂(MoO₄)₃∶Eu荧光材料的微观形貌为片状结构,晶体结构为四方晶型,其发射光谱中出现了Eu3+的特征发射峰;纳米Fe₃O₄磁性材料的微观形貌为球形颗粒,晶体结构为立方晶型,并具有超顺磁性。然后,将以上两种纳米材料以一定比例混合均匀,制备了具有超顺磁性的La₂(MoO₄)₃∶Eu/Fe₃O₄纳米荧光粉末。经表征,该磁性纳米荧光粉末的微观形貌为片状结构与球形颗粒的混合,其发射峰位置未发生变化,而发光强度有所降低,但仍能够满足指纹显现的需要。最后,将制备的纳米磁性荧光粉末用于显现不同类型客体表面的潜在指纹。显现效果表明,对于光滑客体表面的指纹,使用磁性纳米荧光粉末与纳米荧光粉末的显现效果无明显差异;对于粗糙客体表面的指纹,使用磁性纳米荧光粉末能够清晰显现出指纹的细节特征,其显现效果明显优于普通纳米荧光粉末,并能够有效避免粉末扬尘现象。本研究制备的纳米磁性荧光粉末是一种理想的指纹显现材料,其指纹显现具有背景干扰低、显现效果好、适用范围广、无粉末扬尘等优点,在刑事案件现场具有广阔的应用前景。     

SiO2的赝晶化及AlN/SiO2纳米多层膜的超硬效应

采用反应磁控溅射法制备了一系列不同SiO₂层厚度的AlN/SiO₂纳米多层膜，利用X射线衍射仪、高分辨透射电子显微镜和微力学探针表征了多层膜的微结构和力学性能，研究了SiO₂层在多层膜中的晶化现象及其对多层膜生长方式及力学性能的影响. 结果表明，由于受AlN六方晶体结构的模板作用，溅射条件下以非晶态存在的SiO₂层在其厚度小于0.6 nm时被强制晶化为与AlN相同的六方结构赝晶体并与AlN形成共格外延生长. 由于不同模量的两调制层存在晶格错配度，多层膜中产生了拉、压交变的应力场，使得多层膜产生硬度升高的超硬效应. SiO₂随层厚的进一步增加又转变为以非晶态生长，多层膜的外延生长结构受到破坏，其硬度也随之降低. 关键词： 2纳米多层膜')" href="#">AlN/SiO₂纳米多层膜 赝晶化 应力场 超硬效应     

双离子(40Ar+, C2H+6)辐照合成金刚石纳米晶颗粒

用双离子(⁴⁰Ar⁺，C₂H⁺₆)辐照实验完成了从多壁碳纳米管向金刚石纳米晶颗粒的转变.对转变机理进行了初步探讨.这一探索有望能成为一种金刚石纳米晶合成的新途径.由此可知，多重荷能离子辐照用于其他材料纳米结构的制备也不是凭空设想. 关键词： 金刚石纳米晶 离子辐照 透射电子显微镜     

高压导致纳米TiO2形变的电子显微研究

α-PbO₂相TiO₂高压相具有适宜的带隙能和可见光范围的光催化能力,是一种适用于可见光、高效且环保的光催化材料.本文使用金刚石对顶压砧对锐钛矿纳米球进行加压-卸压处理得到了α-PbO₂相TiO₂高压相.利用透射电子显微镜对比初始样品和卸压样品,观察结果表明晶粒发生了明显形变,高分辨图显示其晶粒中存在大量[100]方向层错和形变孪晶,其中亚微米级晶粒中形成了透镜形片层结构的形变孪晶带;纳米级晶粒中形成了扇形多重形变孪晶.研究表明高压下锐钛矿TiO₂可以发生明显的形变,其形变的微观机制与金属类似,主要为形变孪晶和层错滑移,形变孪晶的形成存在明显的尺寸效应.这些结果为TiO₂高压相变的尺寸效应研究提供了一个新的切入点,同时还为制备孪晶α-PbO₂相TiO₂高压相提供了方法.     

Er2(Fe1-xCox)15Ga2化合物的磁晶各向异性

通过X射线衍射和磁性测量等手段研究了Er₂(Fe_1-xCo_x)₁₅Ga₂化合物的结构与磁性，重点讨论了它们的磁晶各向异性.实验结果表明，Er₂(Fe_1-xCo_x)₁₅Ga₂化合物均为Th₂Ni₁₇型六角结构，晶格常数a,c和单胞体积V随Co含量的 关键词：     

Physicochemical properties of core/shell structured pyrite FeS2/anatase TiO2 composites and their photocatalytic hydrogen production performances

A new photocatalytic system using anatase TiO₂ loaded onto pyrite FeS₂ (FeS₂/TiO₂) was developed to enhance the production of hydrogen. The FeS₂ (3.0, 5.0, 10.0, and 15.0 wt-%)/TiO₂ particles in SEM photos showed a core/shell structure composed of pyrite FeS₂ with a grape-like morphology of length of ～1.0 μm and anatase TiO₂ of diameter <50 nm. The evolution of H₂ by methanol/water (1:1) photo splitting over FeS₂/TiO₂ in a liquid system was enhanced as compared with that obtained using pure TiO₂ and FeS₂. In particular, 9.8 mmol of H₂ gas was produced in 10 h when 0.5 g of a 10.0 wt-% FeS₂/TiO₂ core/shell composite was used. Hydrogen production was increased by adding KOH electrolyte to 11.2 mmol. On the basis of cyclic voltammetry (CV) and UV–visible spectra results, this photoactivity of the FeS₂/TiO₂ composite was attributed to a shorter band gap than those of pure TiO₂ and FeS₂.     

Controlled growth of uniform nanoflakes-built pyrite FeS<Subscript>2</Subscript> microspheres and their electrochemical properties

Nanoflakes-built pyrite FeS₂ microspheres were synthesized through a simple solvothermal process in mixed solvents of N, N-dimethytformamide and ethylene glycol without using any surfactant. Both the composition of the solvents and urea were key factors for the formation of the uniform products. It was found that the flake-like intermediate products transformed into FeS₂ nanoflakes in situ in the early stage and Ostwald ripening growth mechanism would contribute to the uniformity of the final products. Electrochemical studies revealed that the nanoflakes-built pyrite FeS₂ microspheres exhibited large lithium storage capacities. This method can be easily controlled and is expected to be extendable to the fabrication of other metal chalcogenides with controlled shape and structure.     

Hydrothermal synthesis of FeS2 for lithium batteries

Nanocrystalline FeS₂ cathode material of lithium cell was synthesized from cheap materials of FeSO₄, Na₂S₂O₃, and sulfur by a hydrothermal process. The scanning electron microscopy analysis showed the obtained material was nano-sized, about 500 nm. The X-ray powder diffraction analysis showed that the synthetic FeS₂ material had two phases of the crystalline structure, pyrite and marcasite. The phase of marcasite seems to have no negative effect on the electrochemical performance of the material. The synthetic FeS₂ showed a significant improvement of electrochemical performance for Li/FeS₂ cells.     

A 57Fe Mössbauer study of four pyrite compounds: CoS2, NiS2, CoSe2 and NiSe2

Mössbauer spectra of ⁵⁷Fe-doped CoS₂, NiS₂, CoSe₂ and NiSe₂ have been taken at various temperatures between 300 and 16 K, and the hyperfine parameters H and θ measured for those substances showing magnetic hyperfine splitting. Quadrupole splitting $\text{QS}\text{(=}\text{1}\text{2}\text{e}{}^2\text{qQ)}$ was also measured and for NiS₂ and CoS₂ the sign of QS was determined.The room temperature value of QS showed a similar behaviour in the series FeS₂CoS₂NiS₂ to that in the series FeSe₂CoSe₂NiSe₂. The absolute value of QS decreased slightly below the magnetic transition temperature in those compounds which showed magnetic ordering.     

Transformations of Pyrite and Pyrrhotite in Supercritical Water

The interaction of pyrite (FeS₂) with water at the uniform heating (1.5 K/min) of the reaction mixture to 923 K and its subsequent cooling (about 3 K/min) to 423 K is studied. The reaction products are analyzed using the methods of mass-spectrometry, elemental and X-ray diffraction analyses, and scanning electron microscopy. It is established that H₂S, SO₂, and rhombic and hexagonal pyrrhotite (FeS) are formed while heating, and the subsequent cooling of the reaction system gives rise to the formation of H₂S, H₂, cubic pyrite, and monoclinic pyrrhotite exhibiting ferromagnetic properties. It is shown that the transformations FeS₂ → FeS → FeS _x (1 < x ≤ 2) are accompanied by changes in the morphology and size of particles.     

EDTA辅助水热合成FeS2/NiSe2复合纳米晶及其薄膜光电性质

以EDTA为螯合剂,加入MX2结构化合物NiSe_2作为晶种,水热合成了FeS_2 纳米晶 .x射线衍射分析结果表明产物为单一相黄铁矿型FeS_2 (pyrite) ,平均粒径约 4 0— 5 0nm .丝网印刷成膜且高温退火后FeS_2 薄膜光学直接带隙变宽 .随晶种量的增加 ,吸收边在紫外—可见光谱区红移、方块电阻升高、霍尔迁移率上升和载流子浓度下降 ,实现了n型掺杂 .并且对FeS_2 的形成机理进行了讨论     

Force field of FeS2 with pyrite structure at zero wave vector

Published experimental frequencies are used to calculate force field and effective charge of FeS₂ with pyrite structure. The values obtained are discussed. Some preliminary calculations on MnS₂ are reported.     

同步辐射光激励的二氧化硅薄膜刻蚀研究

利用热氧化法在硅晶片上生长SiO₂薄膜，结合光刻和磁控溅射技术在SiO₂薄膜表面制备接触型钴掩模，通过掩模方法在硅表面开展了同步辐射光激励的表面刻蚀研究，在室温下制备了SiO₂薄膜的刻蚀图样.实验结果表明：在同步辐射光照射下，通入SF₆气体可以有效地对SiO₂薄膜进行各向异性刻蚀，并在一定的气压范围内，刻蚀率随SF₆气体浓度的增加而增加，随样品温度的下降而升高；如果在同步辐射光照射下，用SF₆和O₂的混合气体作为反应气体，刻蚀过程将停止在SiO₂/Si界面，即不对硅刻蚀，实现了同步辐射对硅和二氧化硅两种材料的选择性刻蚀；另外，钴表现出强的抗刻蚀能力，是一种理想的同步辐射光掩模材料. 关键词： 同步辐射刻蚀 接触型钴掩模 二氧化硅薄膜     

使用硫化物纳米前驱物墨水法制备铜铟硫薄膜

提出了一种通过反应烧结来制备CuInS₂多晶薄膜的低成本旋涂工艺路线．通过将前驱物粉末在氢气中预还原的方法来优化旋涂时使用的墨水成分,氢气还原会使前驱物纳米粉末从硫化物混合粉末转变成CuInS₂和Cu-In合金的混合物．扫描电子显微镜、电子能谱、X射线衍射以及拉曼图谱的结果表明,这种优化能极大的提高CuInS₂多晶薄膜的性能,其中包括薄膜的排列密度更高,杂质相减少,薄膜质量变得更好等．吸收光谱测得优化后的铜铟硫薄膜的带隙约为1.45 eV．     

Ab initio study of phonon dispersion and thermodynamic properties of pure and doped pyrites

Pyrites (FeS₂) are solid minerals that are found abundantly in Nigeria and are easy to prepare in laboratories. In this work, FeS₂ is studied extensively in its pure state as well as when iron is substitutionally doped with zinc and calcium at concentrations of 0, 0.25, 0.5, 0.75 and 1. Using density functional theory, the eectronic, dynamic and thermodynamic properties were calculated. The results revealed that the lattice parameters and bulk modulus increases with increasing concentration and the obtained values are in agreement with available experimental and theoretical values. Though pyrite, when doped with zinc, obeys Vegard’s law, doping with calcium revealed pronounced deviation from this law. The calculated band structures showed that FeS₂ has an indirect band gap whose size decreases after introducing zinc while doping with calcium increases the band gap. The phonon dispersion of the end members FeS₂ and ZnS₂ indicate that the systems are dynamically stable while CaS₂ is dynamically unstate. Also, the thermodynamic properties of the pure and doped pyrites were calculated and the ranges of temperature at which the lattice and electronic degrees of freedom contribute to the specific heat capacity are presented.