ZrO2和ZrO2:Dy3+纳米晶发光特性

采用液相沉淀法制备了不同掺杂浓度和尺寸的ZrO2和ZrO2Dy纳米晶,研究了其发光特性.结果表明在纳米ZrO2中,存在着宽带激发和发射,起源为电子在价带和导带之间的跃迁.在Dy3+掺杂的样品中,随着颗粒尺寸的长大,其发光增强.并且共掺杂Li+的样品发光强度被极大地提高.随着Dy3+浓度的变化,黄发射和蓝发射的强度比(Y/B)发生改变,且浓度猝灭是通过近邻激活剂间的交换作用进行的.     

纳米La2O3:Eu的结构及其光致发光性质研究

采用共沉淀法制备出纳米级La2O3Eu.并采用相关光谱、X-射线衍射(XRD)、荧光光谱(PL)对所制备的纳米发光粉体进行表征.结果表明制备的纳米发光粉体的粒径均匀,集中在20nm左右;XRD结果证明制备的La2O3Eu粉体属于六方相,PL的结果说明La2O3Eu具有良好的发光性质.     

静电纺丝制备的ZrO2纳米纤维及其应用的研究进展

制备超细、高性能ZrO2纤维是实现其在催化、能源及环境等领域工程应用的关键。静电纺丝技术是一种近年来兴起的氧化物陶瓷纳米纤维制备新方法,能够制备直径较小、均一性高、连续性好的ZrO2纳米纤维,并且可通过控制前驱体纺丝液组成、静电纺丝工艺及热处理参数,对ZrO2纤维的组成、结构及性能进行调控。介绍了ZrO2纳米纤维制备、结构及性能方面的研究进展,并对经由原料组成、静电纺丝工艺及热处理条件调控的ZrO2纳米纤维结构、性能以及应用进行了综述和分析。     

高折光率环氧/ZrO2纳米杂化材料的制备

采用溶胶-凝胶法在环氧E51中原位生成无机纳米ZrO₂团簇,并利用有机环氧分子链上的侧羟基与无机纳米团簇间形成化学键,以增加有机无机组分间的相容性,并防止无机纳米团簇在体系中团聚。采用红外光谱、X射线衍射、扫描电镜、原子力显微镜和透射电镜等对其结构进行了表征,证明成功地在体系中原位生成了ZrO₂纳米粒子且分布均匀,所制备的薄膜材料具有很好的平整度。环氧/ZrO₂纳米杂化光学材料的折光率随着体系中无机纳米粒子含量的增加而呈线性增加,并实现折光率在1.512~1.749间连续可调;在可见光波长范围内,环氧/ZrO₂纳米杂化光学薄膜的透过率普遍维持在85%以上,当纳米粒子的含量增至25%后,透光率也能保持在80%以上。     

ZrW2O8 / ZrO2 可控热膨胀复合材料的制备

采用分步加热固相法成功制备了纯度较高的各向同性负热膨胀材料ZrW₂O₈ 。将ZrW₂O₈ 与ZrO₂ 按一定比例混合, 在1200 ℃烧结24 h 制备了热膨胀系数可控的ZrW₂O₈ / ZrO₂ 复合材料。研究结果表明, 通过改变ZrW₂O₈ 的体积分数, ZrW₂O₈ / ZrO₂ 复合材料的热膨胀系数可以控制为负、正或零。当ZrW₂O₈ 的体积分数为37 %时, 复合材料的热膨胀系数接近零。为了得到致密的ZrW₂O₈ / ZrO₂ 复合陶瓷, 采用Al₂O₃ 作为烧结剂, 取得了较好的效果。0. 35 wt % Al₂O₃ 的加入可以在不影响复合材料热膨胀性能的前提下, 显著提高复合材料的致密度。      

高折射率ZrO2纳米杂化材料的制备与研究

以4,4’-二羟基二苯硫醚和9,9-二(4-羟苯基)芴,环氧氯丙烷为原料,在碱性条件下缩聚合成一种含S元素含芴结构的环氧树脂基体;通过溶胶-凝胶法,以四正丁醇锆为前驱体,以KH560为偶联剂,在基体上原位合成无机纳米ZrO₂粒子,再经过热固化制备出一种具有高折射率的光学纳米杂化材料。通过红外光谱、¹H核磁共振、X射线衍射、纳米粒度仪等手段对杂化材料的结构进行表征,并采用紫外分光光度仪、热重分析仪、椭圆偏振光谱仪对其性能进行了表征与测试。结果表明：ZrO₂粒子在聚合物基体中合成,并以纳米粒度均匀分散,杂化材料具有很好的光学性能,在可见光范围内普遍保持90%以上的透过率,随着ZrO₂含量的增加,杂化树脂折射率呈线性增加,ZrO₂含量在19.33%时,折射率达到1.739。     

环氧丙烷辅助制备ZrO2-SnO2复合溶胶的通用方法

以八水氧氯化锆和五水氯化锡为前驱体,通过环氧丙烷辅助制备出ZrO2-SnO2复合溶胶。研究了各添加剂和溶剂对体系的pH值以及凝胶时间的影响,并利用TG-DTA和XRD研究了热处理之后干凝胶的结构和组成。结果表明:当溶胶固含量为2wt%时,以RPO/Cl=1.5/1、水醇比VW/E=1/3、加入稀硝酸的量为1.5mL/100mL为配比制备的ZrO2-SnO2复合溶胶可以长时间保持稳定。所得溶胶粒子的平均粒径约为33.5nm。所得干凝胶在500℃～550℃处理后其组成为四方相ZrO2、四方相SnO2以及正交相ZrSnO4。     

超细ZrO2室温凝胶注模成型研究

为了探讨凝胶注模成型工艺在超细粉体领域的应用,研究了超细ZrO2粉体室温下的凝胶过程.通过记录凝胶过程中料浆温度的变化,采用扫描电镜观察坯体显微组织结构,并检测材料强度等方法,研究了去离子水/单体/交联剂的比例及引发剂和催化剂用量对超细ZrO2室温凝胶过程的影响.研究表明:去离子水/单体/交联剂比例(质量比)以100/15/1为宜,此时可形成稳定的网络结构;调整引发剂和催化剂的用量及比例,可以控制料浆的停留时间和聚合反应时间,在预混液/引发剂/催化剂比例(体积比)为100/1/0.5时,停留时间和聚合反应时间分别为20min和28min;超细ZrO2粉体凝胶注模成型工艺可以在室温下进行.     

ZrO2(Y2O3)含量对双峰晶粒度分布Mo-12Si-8.5B-ZrO2(Y2O3)复合材料力学性能的影响

多相Mo-12Si-8.5B合金是一种很有应用前景的高温结构材料,为了同时提高Mo-12Si-8.5B合金的强度和韧性,提出了采用纳米ZrO₂(Y₂O₃)强韧化具有双峰晶粒度分布Mo-12Si-8.5B复合材料的方法。首先采用溶胶-凝胶和高温氢还原法制备了纳米Mo-ZrO₂(Y₂O₃)复合粉末,然后以纳米Mo-ZrO₂(Y₂O₃)粉末和微米Mo粉末为原材料,采用放电等离子烧结(SPS)技术制备了具有双峰晶粒度分布的Mo-12Si-8.5B-ZrO₂(Y₂O₃)复合材料。结果表明,随着ZrO₂(Y₂O₃)含量的增加,制备的Mo-ZrO₂(Y₂O₃)纳米粉末的粒度和烧结体相对致密度均逐渐减小,ZrO₂(Y₂O₃)含量小于2.5wt%时,烧结体的相对致密度均大于98.1%。当ZrO₂(Y₂O₃)含量为1.5wt%和2.5wt%时,复合材料具有较高的硬度(9.76~9.98 GPa),抗弯强度(672~678 MPa)和断裂韧性(12.68~12.82 MPa·m1/2)。Mo-12Si-8.5B-ZrO₂(Y₂O₃)复合材料中Mo晶粒细化、粗细Mo晶粒的晶界强化和纳米ZrO₂(Y₂O₃)颗粒第二相强化是提高硬度和抗弯强度主要原因;复合材料中粗晶粒Mo和纳米ZrO₂(Y₂O₃)有助于断裂韧性的提高,材料的增韧机制主要是裂纹偏转和裂纹桥接。      

ZrO2微粉表面化学镀镍动力学研究

化学镀法制备Ni包覆ZrO     

Photoluminescence and preparation of ZnNb2O6 doped with Eu and Tm nanocrystals for solar cell

Synthesis and luminescence properties of Eu³⁺ and Tm³⁺-doped ZnNb₂O₆ nanocrystals by the sol–gel process were investigated. The products were characterized by differential thermal analysis (DTA), scanning electron microscopy (SEM), and photoluminescence spectroscopy (PL). ZnNb₂O₆:Eu³⁺ shows bright red luminescence with maximum peak at 613 nm attributed to ⁵D₀ → ⁷F₂ transition. The major blue emission peak of ZnNb₂O₆:Tm³⁺ was at 483 nm, corresponding to the transitions ¹G₄ → ³H₆. The optimum concentration of Eu³⁺ and Tm³⁺ showing the maximum PL intensity was 4 mol% and 1 mol%, respectively.     

金属离子掺杂TiO2的光催化性能研究

用醇盐水解法制备了Ce4+、Ag+、Fe3+、Fe2+、Sn4+、Zn2+、Mo6+等金属离子掺杂的TiO2复合微粒.以罗丹明6G降解为目标反应,研究了所制备的复合微粒光催化活性与选择性.并用IR、XRD、TEM及BET等技术,对TiO2复合微粒进行了表征.结果显示在TiO2内掺入Ce4+、Ag+、Sn4+,可使纳米TiO2的光催化活性增强,而Fe3+、Fe2+、Zn2+、Mo6+等金属离子掺杂的二氧化钛复合微粒的催化活性呈下降趋势.     

Microstructure control for sputter-deposited ZrO2, ZrO2·CaO and ZrO2·Y2O3

The microstructure of pure and oxide-stabilized cubic ZrO₂ has been determined as a function of the principal deposition conditions for coatings prepared by r.f. diode reactive sputtering. Broad control of crystal structure, phase composition, grain size and crystallographic orientation is obtained by appropriate selection of the target composition, substrate bias and substrate temperature. The crystal structure and phase composition obtained for coatings are compared with predictions based on the equilibrium phase diagrams. The microstructural control demonstrated in this work should make possible rapid, efficient and systematic optimization of ZrO₂ coatings for future engineering applications.     

Efficient two-color luminescence of Er/Yb/Li:ZrO2 nanocrystals

We demonstrate the upconversion-photoluminescence spectra of Er³⁺, Yb³⁺ and Li⁺ ions doped ZrO₂ nanocrystals. By introducing Li⁺, emission intensities of single green and single red band increase by a factor of 1.93 and 1.65, respectively. Powder X-ray diffraction data and decreased slopes of the excitation power dependences on upconverted emission intensities give evidences that Li⁺ ions can tailor the local structure of host lattice and improve energy transfer processes from Yb³⁺ to Er³⁺, respectively.     

Photoluminescence of Bi ions in sol-gel derived Zn2SiO4

The luminescence of sol-gel derived Zn₂SiO₄ powder sample doped with Bi³⁺ ions has been presented in this paper. From the photoluminescence (PL) spectra of the doped sample, it can be concluded that Bi³⁺-doped Zn₂SiO₄ powder is an interesting PL material whose luminescence properties are adjusted by changing the excitation wavelength. The luminescence of Bi³⁺ ions is quite diverse in Zn₂SiO₄ powder sample. The blue and yellow emission bands have been observed from the doped Zn₂SiO₄ powder. This novel luminescence property is attributed to an energy transfer involving Bi³⁺, Zn²⁺, and Si⁴⁺ ligand of Zn₂SiO₄ lattice.     

Synthesis and characterization of Mo doped hierarchically porous SO4/ZrO2 solid acid catalyst

A novel hierarchically porous molybdenum-promoted SO₄²⁻/ZrO₂ solid acid with nanocrystallized framework of tetragonal phase and high surface area has been synthesized via a composite surfactant-assisted route combined with a hydrothermal treatment process. The XRD, N₂-adsorption, TEM, and FT-IR pyridine adsorption were used for the structural analysis and acidic characterization. The results show that the novel mesoporous solid acid exhibits classical tetragonal phase and excellent catalytic performance in the esterification reaction of acetic acid with n-butanol and can preserve the acid better than normal solid acids after several recycle experiments. This hierarchically zirconia solid acid has a good potential as catalysts in some chemical reactions such as esterification.     

Directionally solidified ZrO2-Ta and ZrO2(Y2O3)-Ta composites

Aligned eutectic composites of unstabilized ZrO₂-Ta and Y₂O₃-stabilized ZrO₂-Ta were grown by direct internal zone melting. Samples with unstabilized ZrO₂ were almost completely crack-free even though the matrix had transformed from the tetragonal to the monoclinic lattice. Stabilized ZrO₂-Ta composites were heavily cracked and exhibited less homogeneous fiber growth. The Ta fiber diameter in unstabilized eutectics decreased from 0.45 to 0.20 μm, as growth rates increased from 4.4 to 27 cm/h. The fracture of the composites always took place in a controlled manner. The reason is plastic deformation of the fibers and subsidiary crack formation within the twinned ZrO₂ matrix. The Ta fiber ductility is caused by solute Zr which reduces the oxygen solubility of Ta considerably.     

Fluorite related ordered compounds in the ZrO2CaO and ZrO2Y2O3 systems

ZrO₂:CaO and ZrO₂:Y₂O₃ systems have been examined for possible ordered compounds. Fluorite related ordered compounds CaZr₄O₉ and Zr₃Y₄O₁₂ have been successfully prepared and identified. While it is believed that the former is monoclinic with $\text{a}\text{= 17.813 ± 0.005}\text{A}\text{?}$, $\text{b}\text{= 14.612 ± .004}\text{A}\text{?}$, $\text{c}\text{= 12.065 ± .003}\text{A}\text{?}$ and β = 119.5 ± .02° and isostructural with CaHf₄O₉, the latter appears to be isostructural with M₇O₁₂ type of compounds with $\text{a}\text{= 9.723 ± .001}\text{A}\text{?}$ and $\text{c}\text{= 9.090 ± 0.002}\text{A}\text{?}$, which is formed commonly in compounds containing tri and tetravalent cations and is characterized by a chain oxygen vacancy along a 〈111〉 of the original fluorite. No other fluorite related ordered compound could be detected in these systems.     

Electrical characteristics of a ZrO2/SiO2 modified tunnel barrier for low-temperature non-volatile memory

The electrical characteristics of nonvolatile memory, which consists of an asymmetrical ZrO₂/SiO₂ (ZO) modified tunnel barrier, a high-k HfO₂ trapping layer and an Al₂O₃ blocking layer, were investigated for the application of a tunnel barrier engineered nonvolatile memory at low process temperatures. The efficiency of the ZO modified tunnel barrier on the charge trap flash (CTF) memory cell was compared to a conventional single SiO₂ tunnel barrier. The ZO tunnel barrier revealed field sensitivity larger than the single SiO₂ tunnel barrier. The programming and erasing speeds as well as the retention and endurance characteristics of CTF memory were largely enhanced. Moreover, the forming gas annealing process in 2% diluted H₂/N₂ ambient improved the charging trapping property and tunneling sensitivity of the ZO modified tunnel barrier.