Acid base and catalytic properties of Zr02 - Y203 systems

The surface acidity and basicity of mixed oxides of Zr and Y and their mixed oxides have been determined by titration method using Hammett indicators. The acid base properties are evaluated on a common scale of acid strength. Liquid phase reduction of cyclohexanone has been selected as a model reaction to correlate catalytic activity.

Gibbs energy of formation of nickel orthosilicate (Ni2SiO4)

Two solid state galvanic cells:Pt, Ni + Ni2Si04 + Si02/(Y203)Zr02/Ni + + NiO, Pt (1) and Pt, Ni + NizSiOj + Si02/CaF2/Ni + + NiO, Pt (11) have been employed for the determination of the Gibbs' energy of formation of nickel orthosilicate(Ni2Si04) from nickel oxide and quartz. The emf of cell (I) was reversible and reproducible in the temperature range 925 to 1375K whereas emf of cell (11) drifted with time and changed polarity. From the results of cell (I), the Gibbs' energy of formation of nickel silicate is obtained as,2Ni0 (r.s.) + Si02 (quartz) + Ni2Si04 (olivine)Gibbs' energy of formation of the spinel form of Ni2Si04 is obtained by combining the data for olivine obtained in this study with high pressure data on olivine to spinel transition reported in the literature. The complex time dependence of the emf of cell (11) can be rationalised on the basis of formation of calcium silicates from calcium oxide, generally present as an impurity in the calcium fluoride electrolyte, and silica. The emf of cell (11) is shown to be the function of the activity of calcium oxide at the electrolyte/ electrode interface. The results provide strong evidence against the recent suggestion of mixed anionic conduction in calcium fluoride.

Measurement of the Gibbs energy of formation of URh3 using an oxide solid electrolyte

The Gibbs' energy offormation of the intermetallic compound URh3has been measured in the temperature range 980 to 1320 K using an oxide solid state cell incorporating yttria-doped thoria as the solid electrolyte and a mixture of manganese and manganese oxide as the reference electrode. The cell can be represented as Pt, Mn + MnO I (Y203)Th02 I Rh + URh3 + U02 + x' Rh, Pt The reversible emf of the cell was a linear function of temperature E = 15.60 +0.0237 T (±0.8) mY. Using auxiliary thermodynamic data for MnO and U02+ x the Gibbs' energy of formation of URh3 from component metals has been computed. The results can be expressed by the equation L'.G?< URh3 > = -316240 + 13.22 T (± 3000) J mol-1. The "third-law" enthalpy of formation of URh3at 298 K is -293.2 (± 4) kJ mol-1, significantly more negative than the value of -181.5 kJ mol-1 calculated using Miedema's model.

Phase relations in the system SrO-Y2O3-CuO-O2 and CaO-Y2O3-CuO-O2 at 1173 K

Phase relations in the systems SrO-Y2O3-CuO-O2 and CaO-Y2O3-CuO-O2 at 1173 K were established by equilibrating different compositions in flowing oxygen gas at a pressure of 1.01 × 105 Pa. The quenched samples were examined by optical microscopy, X-ray diffraction (XRD), energy dispersive analysis of X-rays (EDAX), and electron spin resonance (ESR). In the system SrO-Y2O3-CuO-O2, except for the limited substitution of Y3+ for Sr2+ ions in the ternary oxide Sr14Cu24O41, no new quaternary phase was found to be stable. The compositions corresponding to the solid solution Sr14−xYxCu24O41 and the compound SrCuO2+δ lie above the plane containing SrO, Y2O3, and CuO,displaced towards the oxygen apex. However, in the system CaO-Y203-CuO-O2 at 1173 K, all the condensed phases lie on the plane containing CaO, Y203, and CuO, and a new quaternary oxide YCa2Cu306.s is present. The quaternary phase has a composition that lies at the center of the nonstoichiometric field of the analogous phase YBa2Cu307_~ in the BaO-Y203-CuO-O2 system. The compound YCa2Cu306.s has the tetragonal structure and does not become superconducting at low temperature. Surprisingly, phase relations in the three systems CaO-Y203-CuO-O2, SrO-Y203-CuO-O2, and BaO-Y203-CuO-O2 are found to be quite different.

RF plasma MOCVD of Y2O3 thin films: Effect of RF self-bias on the substrates during deposition

Yttrium oxide (Y203) thin films have been deposited by radio frequency plasma assisted metal organic chemical vapor deposition (MOCVD) process using (2,2,6,6-tetramethy1-3,5-heptanedionate) yttrium (commonly known as Y(thd)3) precursor in a plasma of argon and oxygen gases at a substrate temperature of 350 C. The films have been deposited under influence of varying RF self-bias (-50 V to 175 V) on silicon, quartz, stainless steel and tantalum substrates. The deposited coatings are characterized by glancing angle X-ray diffraction (GIXRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), spectroscopic ellipsometry and scanning electron microscopy (SEM). GIXRD and FTIR results indicate deposition of Y2 03 (BCC structure) in all cases. However, XPS results indicate nonstoichiometric cubic phase deposition on the surface of deposited films. The degree of nonstoichiometry varies with bias during deposition. Ellipsometry results indicate that the refractive index for the deposited films is varying from 1.70 to 1.83 that is typical for Y203. All films are transparent in the investigated wavelength range 300-1200 nm. SEM results indicate that the microstructure of the films is changing with applied bias. Results indicate that it is possible to deposit single phase cubic Y203 thin films at low substrate temperature by RF plasma MOCVD process. RF self-bias that decides about the energy of impinging ions on the substrates plays an important role in controlling the texture of deposited Y203 films on the substrates. Results indicate that to control the structure of films and its texture, it is important to control the bias on the substrate during deposition. The films deposited at high bias level show degradation in the crystallinity and reduction of thickness. (C) 2013 Elsevier B.V. All rights reserved.

介孔材料的合成、性能以及应用

自从1992年美孚公司成功地研究开发出介孔材料M41S后，由于其具有不同寻常的结构特点-比较均一的孔径（2-50nm）而且连续可调、较高的比表面积、较大的孔体积、孔的长程有序性以及较好的热稳定性等，具有巨大的潜在应用价值，立即引起了全世界的关注。目前，世界各国的研究主要集中在研究介孔材料的特性、形成机理、介孔材料形貌、结构和孔径的控制、新一代介孔材料的研究开发、介孔材料的改性以及介孔材料的应用等方面。本论文主要在介孔材料的合成、性能以及应用方面开展了研究。选用头尾都是憎水的三嵌段共聚物为模板制备出具有三维无序虫状孔道的介孔材料和以有孔氧化铝膜为模板制备了形态可控的介孔材料，即具有介孔结构高有序纳米管。采用一步法合成了介孔Ag／silica和Y2O3：Eu／silica材料，采用基底受限法制备了银和Y2O3：Eu纳米粒子，同时研究了Ag／silic。作为催化剂时催化性能。（1）在酸性条件下，利用头尾都是憎水的三嵌段共聚物SBS为模板、TEOS为硅源，分别选用丁酮和甲苯作选择性溶剂，通过微乳技术制备出具有三维无序虫状孔道的介孔硅材料。我们通过在SBS胶束溶液中加入TEOS／水的油水混合乳液使SBS胶束与TEOS／水混合乳液之间形成一个界面，从而使TEOS这个界面上完全水解而且生成的小分子硅齐聚物包附在SBS胶束的外表面。经过加热则使TEOS凝聚同时形成具有介孔结构的SBS／硅材料。最后，通过锻烧以移除SBS，从而得到介孔硅材料。在选用甲苯作溶剂，研究发现随着SBS用量的增加或形成胶束温度的升高比表面积、孔体积和孔径等都相应减小。因此，这两个参数可以方便地调节介孔材料的孔径、表面积和孔体积等，进而更好地控制介孔材料的性能。所制备介孔材料的壁厚与SBS用量和形成胶束温度无关，且均超过IOnm，因而材料具有较好的热稳定性，这有利于其进一步在催化剂、吸附和分离等领域应用。（2）以有孔的氧化铝膜为模板制备了具有介孔结构高有序纳米管，即在加热条件下将P123一TEOS薄膜通过毛细力引入有孔的氧化铝膜孔内，同时根据优先润湿机理使P123一TEOS组分润湿氧化铝孔的内壁并同时伴随嵌段共聚物胶束的重排、TEOS组分的凝聚收缩，随后通过烧结手段除去嵌段共聚物、通过溶解手段除去氧化铝模板，这样便在硅基底上得到了形态可控的介孔材料即有序排列的具有介孔结构的纳米管。在一定时间范围内，退火时间对纳米管的形成和生长高度有一定的影响。纳米管垂直于硅基底且纳米管套内的介孔以六方形式排列在整个纳米管套同时介孔孔道相互平行，所制备的纳米管能保持受限在氧化铝模板时的尺寸而且稳定地粘附在硅基底上。（3）在酸性条件下，采用一步法即在模板剂（P123）形成胶束之后，加入硝酸银或氧化铺和氧化忆混合物同P123胶束形成新的复合体，随后加入硅源（TEOS）以包附在复合体的外表面，从而形成具有介孔相的复合物，通过热处理我们分别制备了高有序的具有二维六方结构的介孔Ag／silica和Y203：Eu／silica材料，其中金属银或YZO3：Eu纳米粒子分散在有序的介孔孔道内。二者的比表面积、孔体积和孔径分别为786m2／g、1．22cm3／g、6．Znm和791m2／g、0．95cm3／g、3．snm。另外，我们采用基底受限法，利用旋涂法分别使介孔Ag／silica和YZO3：E记silica材料分散在硅基底上，通过溶解法除去硅墙后便得到了没有聚集的且具有狭窄粒径分布的金属银（2．5-5．snm）和姚03：Eu（1．5-3．onm）纳米粒子。原子力显微镜（AFM）证实所得到的纳米粒子呈现良好的分散状态，具有狭窄的粒径分布而且粒子尺寸都小于其介孔材料孔径。（4）分别用一步法制备的介孔Ag／SBA－－15材料和金属银作为甲醇氧化制备甲醛反应的催化剂，利用甲醇转化率表示催化剂活性、甲醛和二氧化碳产率表示催化剂选择性来研究二者催化性能。由于具有高的比表面积（786扩／g）、较大的孔体积（1．22cm3／g）、较大的孔径（6．2nm）、狭窄的孔径分布和有序的介孔孔洞等特性，在反应温度473K-723K范围内，同本体银作催化剂相比尽管银仅占体系总重量的0．94wt％，介孔Ag／silic。材料却显示出极高的催化活性和催化选择性。

重离子辐照阿维菌素产生菌的诱变选育

应用不同剂量12C+6重离子束对出发菌株ZJAV-A1进行辐照选育,并应用高效液相色谱法测定发酵液中有效组分B1a的含量.结果表明:当重离子束12C+6离子的辐照剂量为50Gy时,B1a含量的延变率最高,为34.2%;诱变后的菌落共培养出4种菌型,即草帽型、馒头型、光秃型和皱缩型,其中,草帽型高产菌株ZJAV-Y203的发酵液中B1a组分比出发菌株提高了51.43%.说明利用12C+6重离子束辐照处理阿维菌素产生菌,可以得到高产B1a组分的诱变菌株,其诱变效果显著.

纳米粉掺杂的Y2O3-ZrO2陶瓷的制备

采用纳米粉掺杂烧结制备了Y203-ZrOz陶瓷。测试发现，纳米粉的掺入在一定程度上可以使烧结体的密度和硬度得到提高。SEM和EDS分析表明，烧结体表面比较平滑，元素分布比较均匀，有较小的气孔存在。

Surface Electron Donor Properties of Dy2O3,Y2O3 and Their Mixed Oxides with Alumina Catalyst

The limit of electron transfer in electron affinity from the oxide surface to the electron acceptor (EA) are reported from the adsorption of EA on DY203, mixed oxides of DY203 with alumina and mixed oxides of Y203 with y-alumina. The extent of electron transfer is understood from magnetic measurements.

Desenvolvimento e caracterização de dispositivos de visualização eletroluminescentes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Scalable synthetic method for IT-SOFCs compounds

Póster presentado en: 12th EUROPEAN SOFC & SOE FORUM 2016. 5–8 July 2016, KKL Lucerne/Switzerland