ZrO2—Y2O3纳米晶的制备及其湿敏性能

以化学共沉淀法为基础，配合高速剪切均质并添加表面活性剂制备了粒径为２０￣４０ｎｍ的ＺｒＯ２－Ｙ２Ｏ３纳米晶，经ＸＲＤ分析为稳定立方相结构。用ＺｒＯ２－Ｙ２Ｏ３纳米晶为感湿材料制作了厚膜型湿敏元件，测试结果表明：（１）元件电阻随相对温度上升而下降。（２）在总电导中，离子电导占主要成分。（３）元件有较快的感湿响应速度。     

ZrO2基陶瓷超微粉的热分解及晶化过程研究

以Ｚｒ（ＯＣ３Ｈ７）４和Ｙ（ＣＨ３ＣＯＯ）３为原料，应用溶胶－凝胶法制备了ＺｒＯ２＋９％摩尔分数Ｙ２Ｏ３超微粉末。通过ＴＧ－ＤＴＡ，ＸＲＤ分析技术，研究了粉末的热分解过程及晶化过程，结果表明：ＺｒＯ２＋９％Ｙ２Ｏ３超微粉末的热分解过程分为三个阶段；水份和有机溶剂的蒸发；有机基团的燃烧和无定形ＺｒＯ２的形成，无定形ＺｒＯ２向立方相ＺｒＯ２的转变，钇稳定立方相ＺｒＯ２的合成温度在４７０℃左右。     

ZrO2（Y2O3）纳米粉在超高压下快速烧结

研究了超高压（５ＧＰａ）、高温（１３５０℃）下烧结的ＺｒＯ２（Ｙ２Ｏ３）纳米材料的结构及相关系。结果表明：水解法制备的纳米（９ｎｍ）２．２Ｙ－ＺｒＯ２粉体经超高压烧结１０ｓ，致密度即达９９．５％以上，晶粒迅速长大达６０ｎｍ。在０￣９９ｓ范围内，随烧结时间延长，２．２Ｙ－ＴＺＰ的ｔ相增加，四方度（ｃ·ａ＾－１）减小，表明Ｙ２Ｏ３固溶进入ＺｒＯ２晶格内。     

醇-水溶液加热法制备纳米ZrO2粉体及相关过程的研究

分析了醇－水溶液加热法制备纳米ＺｒＯ２（３Ｙ）粉体的过程及加热温度、时间对反应过程及最后所得粉体的影响。研究结果表明,该法制备纳米ＺｒＯ２粉体过程发生了一系列化学反应,这些反应使Ｙ２Ｏ３前趋体在ＺｒＯ２前驱体中均匀分布,Ｙ２Ｏ２在粉体煅烧期间逐渐渗透到ＺｒＯ２颗粒中使之转变为四方相。     

SiC-ZrO2(3Y)-Al2O3纳米复相陶瓷的力学性能和显微结构

本文介绍用非均相沉淀方法制备的纳米ＳｉＣ－ＺｒＯ２（３Ｙ）－Ａｌ２Ｏ３复合粉体经放电等离子超快速烧得到晶内型的纳米复相陶瓷,超快速烧结的升温速率为６００℃／ｍｉｎ,在烧结温度不保温,迅即在３ｍｉｎ内冷却至６００℃以下。     

热处理对ZrO2（8mol%Y2O3）固体电解质电性能的影响

采用化学共沉淀法制备ＺｒＯ２（Ｙ２Ｏ３）超微粉。利用热膨胀法，Ｘ射线衍射分析及复阻抗分析研究热处理温度及升降温速度对ＺｒＯ２（８ｍｏｌ％Ｙ２Ｏ３）固体电解质四方相（ｔ）向单斜相（ｍ）的转变以及晶界偏析的影响。结果表明：降温速度可以改变ｔ－ＺｒＯ２相含量，热处理还会使ｍ相的含量增加，晶粒长大及晶界偏析，从而导致ＺｒＯ２（８ｍｏｌ％Ｙ２Ｏ３）固体电解质电导率下降。     

TiO2—K2O—Y2O3—SiO2陶瓷薄膜结露元件的制备及其湿敏性能研究

采用淀粉产法制备了ＴｉＯ２－Ｋ２Ｏ－Ｙ２Ｏ３－ＳｉＯ２（Ｔｉ：Ｋ：Ｙ：Ｓｉ＝１：０．１＋０．０４＋０．０５,摩尔比）陶瓷薄膜结露元件,研究了陶瓷粉末和薄膜的结构以及元件的感湿性能。６００℃热处理后,陶瓷粉末和薄膜主要由锐钛矿型Ｔdisplay status     

SiC晶须增韧Al2O3及ZrO2（Y2O3）基陶瓷复合材料的抗热震行为

采用三点弯曲及扫描电镜等方法研究了ＳｉＣｗ／Ａｌ２Ｏ３，ＳｉＣｗ／ＺｒＯ２）及ＳｉＣｗ／Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）陶瓷复合材料的抗热震性。结果表明ＳｉＣｗ的加入使Ａｌ２Ｏ３，ＺｒＯ２（Ｙ２Ｏ３）以及Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）基体的抗热震性显著提高，Ａｌ２Ｏ３陶瓷基复合材料的抗热震性明显优于ＺｒＯ２（Ｙ２Ｏ３）陶瓷基复合材料。同时发现在Ａｌ２Ｏ３＋ＳｉＣｗ材料基础上再加入少量ＺｒＯ２９２     

SiC晶须增韧Al_2O_3及ZrO_2（Y_2O_3）基陶瓷复合材料的抗热震行

采用三点弯曲及扫描电镜等方法研究了ＳｉＣｗ／Ａｌ２Ｏ３、ＳｉＣｗ／ＺｒＯ３（Ｙ２Ｏ３）及ＳｉＣｗ／Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）陶瓷复合材料的抗热震性．结果表现ＳｉＣｗ的加入使Ａｌ２Ｏ３、ＺｒＯ２（Ｙ２Ｏ３）以及Ａｌ２Ｏ３＋ＺｒＯ２（Ｙ２Ｏ３）基体的抗热震性显著提高，Ａｌ２Ｏ３陶瓷基复合材料的抗热震性明显优于ＺｒＯ２（Ｙ２Ｏ３）陶瓷基复复合材料．同时发现在Ａｌ２Ｏ３十ＳｉＣｗ材料基础上再加入少量ＺｒＯ２（２Ｙ）颗粒（１０Ｖｏ１％），也可进一步提高Ａｌ２Ｏ３＋ＳｉＣｗ材料的抗热震性．     

Si＿3N＿4－Al＿2O＿3－ZrO＿2系陶瓷表面氧化层组成的EPMA分析

利用ＥＰＭＡ和ＸＲＤ的分析方法，研究了Ｓｉ＿３Ｎ＿４－Ａｌ＿２Ｏ＿３－ＺｒＯ＿２系陶瓷材料表面氧化层组成。结果表明，Ｓｉ＿３Ｎ＿４－Ａｌ＿２Ｏ＿３－ＺｒＯ＿２系陶瓷材料表面氧化层是由方石英相、ＺｒＳｉＯ＿４相和含有Ａｌ＿２Ｏ＿３、ＣａＯ等的ＳｉＯ＿２玻璃相所组成，其中ＳｉＯ＿２玻璃相中Ａｌ＿２Ｏ＿３、ＣａＯ等的含量，随着氧化时间的增加而逐渐增加。     

VLE data for CO2-CF2Cl2, N2-CO2, N2-CF2Cl2 and N2-CO2-CF2Cl

Knowledge about vapour-liquid (VLE) is required as a basis of reliable calculations for separation processes. Correlations available for the prediction of T, p, x, y data are less accurate for mixtures at high pressures and mixtures containing supercritical components. The results of VLE experiments are reported and compared with data calculated with equations of state.     

Thermal diffusion in binary mixtures H2-CCl2F2 and H2-CHClF2

Thermal diffusion coefficients were measured in two gaseous mixtures, in which one component was close to the critical temperature, in the pressure range (19.6–127.4)·10⁴ N/m² and at a freon concentration of 0.25–0.8.     

Preparation of ZrO2-CeO2 and HfO2-CeO2 nanopowders

We prepared weakly agglomerated powders of ZrO₂-CeO₂ and HfO₂-CeO₂ solid solutions 5–8 nm in particle size, consisting of monoclinic and tetragonal phases. After heat treatment at 1200°C, the crystallite size was 30 and 14 nm, respectively. We also examined the effect of precipitate freeze drying on the crystallization of hafnia-based solid solutions containing up to 20 mol % CeO₂.     

Comparison of the Electronic Structures of La2CuO4, Sr2CuO2Cl2, and Sr2CuO2F2

First-principles cluster calculations are reported of the local electronic structure of the three compounds: La₂CuO₄, Sr₂CuO₂Cl₂, and Sr₂CuO₂F₂. The copper ${\text{3d}}_{x^2 - y^2 } $ and the planar oxygen 2p _σ atomic orbitals exhibit a similar degree of covalency. The out-of-plane orbitals, however, are quite different with the ${\text{3}}d_{3z^2 - r^2 } $ atomic orbital lowered significantly in energy for chlorine and fluorine apical positions.     

Radial GRIN glasses in Li2O-Na2O-Al2O3-TiO2-SiO2 systems

A series of GRIN glass rods have been developed in Li2O-Na2O-Al2O3-TiO2-SiO2 systems. Negative radial refractive index profiles were generated by exchanging Na+ for Li+ ions in these glass rods. It has been observed that TiO2 plays a vital role in increase in the profile depth and maximum change in the refractive index because of its ambivalent nature. Change in the refractive index can be further increased by increasing the concentration of exchanging cation in the base glass.     

Thermoelectric power of single-phase samples of Tl2CaBa2Cu2O y and Ba2CaSr2Cu2O y

Single-phase 2122 samples of thallium and bismuth superconductors were made by the precursor matrix method. The thermopower of these samples was measured in the temperature range 250 K-T _c . The thermopower was positive and decreased linearly with increasing temperature aboveT _c (onset). The exponential enhancement of thermopower seen in the undoped and doped YBCO was not observed in these samples. The linear variation of thermopower can be explained on the basis of either a two-band model or a narrow band model.     

Si_2N_2O-Al_2O_3-La_2O_3和Si_2N_2O-Al_2O_3-CaO系统的亚固相关系

本文给出了 Si_2N_2O-Al_2O_3-La_2O_3和 Si_2N_2O-Al_2O_3-CaO 系统的亚固相图。实验结果表明:在 Si_2N_2O-Al_2O_3-CaO 系统中有一个未知结构的新化合物 CaO·Si_2N_2O,在3CaO·Si_2N_2O 和3CaO·Al_2O_3两化合物之间形成连续立方固溶体。而 Si_2N_2O-Al_2O_3-La_2O_3系统中则没有发现新化合物。在两个系统的富 Si_2N_2O区,过量的 Si_2N_2O 与 La_2O_3和 CaO 分别反应形成 Si_3N_4与 La_(10)[SiO_4]_(?)N_2(H-相)(和 CaSiO_3。所研究的这两个三元系统中,分别形成了如下几个四元相容性区。在 Si_2N_2O-Al_2O_3-La_2O_3系统内有:H-Si_3N_4-La_2O_3·Si_2N_2O-La_2O_3·Al_2O_3;H-Si_3N_4-La_2O_3·Al_2O_3-La_2O_3·11 Al_2O_3;H-Si_3N_4-La_2O_3·11 Al_2O_3-Al_2O_3;H-Si_3N_4-Al_2O_3-O′s.s;H-Si_3N_4-O′s.s-Si_2N_2O在 Si_2N_2O-Al_2O_3-CaO 系统内有:Si_3N_4-CaSiO_3-CaO·Si_2N_2O-3CaO·Al_2O_3;Si_3N_3-CaSiO_3-3CaO·Al_2O_3-2CaO·Al_2O_3·SiO_(?);Si_(?)N_(?)-CaSiO_3-2CaO·Al_2O_3·SiO_2-Al_2O_3;Si_3N_4-CaSiO_3-Al_2O_(?)-O′s.s;Si_3N_4-CaSiO_3-O′s.s-Si_(?)N_(?)O     

Elastic and Electronic Properties of Superconducting CaPd 2 As 2 and SrPd 2 As 2 vs. Non-superconducting BaPd 2 As 2

The first-principles calculations were performed to predict the elastic and electronic properties of the superconducting ThCr₂Si₂-type phases CaPd₂As₂ and SrPd₂As₂ in comparison with the non-superconducting CeMg₂Si₂-type phase BaPd₂As₂. Besides, the same properties were compared for CeMg₂Si₂- and ThCr₂Si₂-type polymorphs of BaPd₂As₂. We found that all these phases are mechanically stable and belong to soft materials with low hardness. The near-Fermi region is formed by the valence states of the blocks [Pd₂As₂] with decisive contributions of Pd 4d states. The values of N(E _F) increase in the sequence: CaPd₂As₂ < SrPd₂As₂ < BaPd₂As₂, i.e. in the reverse sequence relative to the transition temperatures T _C. Thus, the change in T _C cannot be explained by the electronic factor, i.e. by the simple correlation T _C～N(E _F). Most likely the decrease in T _C in the sequence CaPd₂As₂ → SrPd₂As₂ and the absence of a superconducting transition in BaPd₂As₂ are related to the structural factors and the peculiarities of the electron–phonon coupling mechanism.