超细Fe3O4粒子表面包覆酞菁钴性质研究

本文研究了合成载氧体的金属有机化学液相淀积法制造工艺，所得产物经ＴＥＭ、ＸＰＳ、Ｍｏｓｓ－ｂａｕｅｒ谱和Ｂ－Ｈ仪等手段，研究了它的结构和磁性能。实验表明，酞青钴以薄层形式包覆在Ｆｅ＿３Ｏ＿４的表面，封闭了Ｆｅ＿３Ｏ＿４的表面孔洞，稳定了Ｆｅ＿３Ｏ＿４的物相，增强了磁性能。     

冲裁模CAD／CAM结构库之原型法

本文首先给出了一种新的2.5D 实体表示法,然后在此基础上提出了“原型”的概念。原型法的思想运用在结构库的管理中主要体现在它将模具结构与构成这种结构的零件之间的强联系变成弱联系,结构库面向的对象是一个具有整体性和可运算性的结构原型。这样的原型结构库基本上达到了通用性与开放性的要求。     

BaFe12O19/SiO2-B2O3微晶玻璃陶瓷的制备和微波性能

采用柠檬酸sol-gel工艺合成了BaFe12O19/SiO2-B2O3微晶玻璃陶瓷，研究了SiO2-B2O3玻璃的含量，Ba/Fe原子比和热处理温度对体系析出晶相的影响，以及介电常数和磁异率在1MHz-6GHz频率范围的变化规律，结果表明，休系中SiO2-B2O3玻璃的含量和Ba/Fe比越高，BaF312O19相的析出越困难，前驱体合适的热处理温度为1000℃，介电常数和磁导率基本上随测试频率的增而加下降；介电损耗的最大值为0．43，磁损耗较小。     

FeBP非晶态合金超细微粒的合成及其对PH3分解的催化作用

用化学还原法合成了FeBP非晶态合金超细微粒，用电感耦合等离子体光谱（ICP）、X射线粉末衍射（XRD）、透射电子显微镜（TEM）和差热分析（DSC）等手段对其进行了物性表征，并用微型催化反应装置考察了其对PH3分解的催化作用，结果表明，非晶态合金FeBP对PH3的分解具有良好的催化作用，能使PH3的分解温度从800℃以上降到500℃左右。490℃时分解率超过90％，540℃时达100％。     

Effects of Ca and Zr substitution upon structure and properties of Ba5LaTi3Ta7O30 low-loss dielectric ceramics

Effects of Ca and Zr substitution upon the dielectric properties of Ba₅LaTi₃Ta₇O₃₀ ceramics were investigated together with the structural characterization. All the samples of Ba₅La(Zr_xTi_1−x)₃Ta₇O₃₀ formed a filled tungsten-bronze structures, whereas the solid solution limit was determined as x=0.25 in (Ca_xBa_1−x)₅LaTi₃Ta₇O₃₀. Beyond this limit secondary phase of CaTa₂O₆ was detected and it would become the major phase for the Ca-rich compositions. The temperature coefficient of dielectric constant was improved with increasing Zr content while the dielectric constant decreased and the low dielectric loss varied little (in the order of 10⁻⁴). In the case of (Ca_xBa_1−x)₅LaTi₃Ta₇O₃₀, small temperature coefficient of dielectric constant could be obtained with increasing Ca content while the dielectric constant decreased significantly, and a small amount substitution of Ca for Ba induced decrease in dielectric loss.     

A comparative study of the gas sensing behavior of nanostructured nickel ferrite synthesized by hydrothermal and reverse micelle techniques

A comparative study of gas sensing behavior of nanocrystalline nickel ferrite synthesized by micro-emulsion and hydrothermal method to liquefied petroleum gas (LPG) is presented. Nanocrystalline nickel ferrite synthesized by hydrothermal method indicated higher electrical conductivity and gas sensitivity at low operating temperature compared to nanocrystalline nickel ferrite synthesized by reverse micelle technique. This difference in the gas sensing behavior can be attributed to the presence of more oxygen vacancies (i.e. non-stoichiometry) in the hydrothermally synthesized nickel ferrite. Incorporation of palladium had a catalytic effect and the operating temperature was significantly reduced in both the samples. The higher operating temperature of the reverse micelle nickel ferrite material makes the sensor response speed faster (∼10 s) compared to the hydrothermally synthesized material (∼1 min).     

Synthesis of LiFePO4 with fine particle by co-precipitation method

LiFePO₄ is a potential candidate for the cathode material of the lithium secondary batteries. A co-precipitation method was adopted to prepare LiFePO₄ because it is simple and cheap. Nitrogen gas was needed to prevent oxidation of Fe²⁺ in the aqueous solution. The co-precipitated precursor shows the high reactivity with the reductive gas, and the single phase of LiFePO₄ is successfully synthesized with the aid of carbon under less reductive conditions. LiFePO₄ fine powder prepared by co-precipitation method shows high rate capability, impressive specific capacity and cycle property.     

Effects of gallia additions on sintering behavior of gadolinia-doped ceria

The effects of gallia additions on the sintering behavior of gadolinia-doped ceria were systematically investigated from the following aspects: the variation in sintered density, the variation in grain size, and the existing forms of Ga₂O₃ in CeO₂.Sintered density increased with increasing Ga₂O₃ content up to 5 mol.% and then it decreased with further addition of Ga₂O₃. Grain size also increased with increasing Ga₂O₃ content up to 5 mol.% and then decreased with further addition of Ga₂O₃. Decrease in grain size was caused by a pinning effect of Ga₂O₃ precipitation at grain boundaries. Lattice constant decreased with increasing Ga₂O₃ content up to 5 mol.%. This decrease will be due to the substitution of smaller Ga³⁺ ions for Ce⁴⁺ ions in the CeO₂ structure. According to the results obtained from scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses, the solubility limit of Ga₂O₃ in Ce_0.8Gd_0.2O_1.9 ceramics can be estimated to be nearly 5 mol.%. The addition of Ga₂O₃ up to the solubility limit was found to promote the sintering properties of Gd₂O₃-doped CeO₂.     

Electrical conductivity and gas sensitivity of Zn-Sb-O thick films

The thick film of Zn-Sb-O was prepared by coating the paste of nanoparticles mixture (Sb₂O₃:ZnO=1:3) on the alumina substrate, followed by sintering at 500-900 °C for 2 h in air. The electrical resistance and gas-sensing properties to benzene, alcohol and acetone of Zn-Sb-O films were found to be dependent on the change of phase structure caused by sintering temperature.