掺银对TiBaCaCuO超导体性能的影响

本文研究了掺入适量的对TiBaCaCuO系超导体超导性能的影响。实验结果表明，当银的掺入量不超过0.3mol时，有利于2223相的形成；在掺入0.3mol银的同时，适当提高组成中Ti或Cu的含量，可以降低烧结温度，并能获得Tco=122K，Tonset=136K的TiBaCaCuO系超导体。     

4-甲基-2-(α-甲基苄基)酚铷钾萃取反应机理及热力学研究

为使卤水中的铷钾得到有效分离,文中研究了4-甲基-2-(α-甲基苄基)酚/脱芳溶剂油在碱性溶液中萃取铷、钾中的反应机理。通过考查分配比与p H值以及萃取剂浓度的关系,采用斜率法与饱和容量法测得了萃合物的组成为MOR·2ROH(M为K~+或Rb~+),确定了萃取反应方程式,证明了该萃取反应为阳离子交换机理,求得表观平衡常数K(Rb)=30.20,K(K)=14.79。通过考查分配比与温度的关系,求得萃取熵ΔS(Rb)=-128.94 J/(K·mol),ΔS(K)=-85.83 J/(K·mol);萃取焓ΔH(Rb)=-29.49 kJ/mol,ΔH(K)=-18.59 kJ/mol;吉布斯自由能ΔG(Rb)=-8.31 kJ/mol,ΔG(K)=-6.57 kJ/mol,证明萃取反应为放热反应,铷的萃取能力大于钾。     

(Al_2O_3,CaO)掺杂对x(MgO)=8%-ZrO_2纳米粉相组成和晶粒大小的影响

用尿素水解法制备了x(MgO)=8%-ZrO2及(Al2O3,CaO)掺杂的x(MgO)=8%-ZrO2纳米粉。经XRD、TEM等分析表明:掺入Al2O3有降低(c+t)-ZrO2体积分数和细化晶粒的作用;CaO的掺入可显著提高(c+t)-ZrO2含量,当掺入x(CaO)=3%时,可得到全稳定立方相氧化锆。     

铋系超导体的成相过程与机制

本文考察了铋系超导体的成相过程,解释了成相机制及高价离子对成相的影响.     

活性焦颗粒在移动床中的传热特性

为研究活性焦颗粒在移动床中的传热特性,以管壳式换热器为换热装置进行传热实验。空气经加热后与活性焦颗粒在换热器的壳程与管程中呈逆流流动,采用控制变量法,改变热空气流速u_s、开始卸料时热空气出口设定温度T_(air)以及活性焦颗粒卸料速度v_p等因素,测定不同实验工况下换热器的传热温差ΔT_m、传热负荷Q及总传热系数K,并观察其变化规律。结果表明,u_s对ΔT_m有很大影响,随着u_s增大,Q和K逐渐增大,在T_(air)=40℃,u_s=16 m/s,v_p=150 kg/h时,K高达9.32 W/(m~2·K),且K与u_s的幂次方n=0.64相关;随着T_(air)的升高,ΔT_m无明显变化,Q与K逐渐降低,T_(air)达到70~80℃后,K几乎无变化;随着v_p增大,ΔT_m增长非常缓慢,Q和K呈线性增长,K大于7.5 W/(m~2·K),v_p每上升50 kg/h,K增加0.9 W/(m~2·K)。     

CaF2-SiO2-CaO渣系的非等温挥发行为

使用同步热分析仪,以10 K/min的升温速率对CaF2-SiO2-CaO三元渣系的失重率进行测定,采用非等温热分析方法对渣系挥发反应动力学进行了研究,确定了渣系挥发的反应机理函数f(a),分析了挥发反应机理,并对建立的动力学模型进行验证. 结果表明,渣系挥发性与其液相线及物相组成密切相关,而碱度对其影响较小;引起渣系成分改变的挥发过程可分为1373~1573 K和1573~1773 K两个阶段,前者属三维扩散型机理函数,其微分形式为f(a)=3/2(1-a)4/3[(1-a)-1/3-1]-1,后者属随机成核和随后生长型机理函数,其微分形式为f(a)=1/4(1-a)[-ln(1-a)]-3. 70%CaF2-30%SiO2渣系2个阶段的反应活化能分别为550.10和376.16 kJ/mol,指前因子1gA分别为16.55和8.4. 实验结果与模型计算结果吻合很好.     

对甲苯磺酸铜催化合成丙二酸二乙酯

以丙二酸和乙醇为原料,采用甲苯磺酸铜作催化剂合成丙二酸二乙酯。考察了催化剂用量、酸醇物质的量比、带水剂用量以及反应时间等因素对收率的影响。确定最佳酯化反应条件:n(丙二酸)=0.1 mol,n(乙醇)=0.3 mol,对甲苯磺酸铜1.0 g,带水剂环己烷20 mL,反应时间60 min。收率可达93.3%。     

纳米氧化高银分散液的制备

运用液相氧化沉淀法制备了纳米级复合氧化高银分散液.探讨了温度、氧化剂用量、过饱和度、分散剂用量以及末期反应时间对分散液颗粒粒径大小和纯度的影响.得到了产品的最佳制备工艺:采用非离子聚乙烯型DJ2004为分散稳定剂、反应温度60℃、DJ200/AgNO3=0.4、K2S2O8/AgNO3=10、末期反应时间-10min、C(AgNO3)=0.18～0.25mol/L.制备出粉体粒径为20～100nm、含氧化高银70%的纳米氧化高银分散液.     

以丙烯腈改性淀粉为分散剂的阳离子苯丙乳液的研制

以丙烯腈改性淀粉为分散剂,采用自由基聚合法在淀粉分子链上接枝苯乙烯(St)、丙烯酸丁酯(BA)、甲基丙烯酸二甲基氨基乙酯(DM)和丙烯酰胺(AM)等共聚单体,合成出一种新型的阳离子型淀粉接枝苯丙乳液施胶剂。探讨了K2S2O8/NaHSO3氧化还原型引发剂、共聚单体等对施胶剂施胶效果的影响。结果表明:当w(DM)=2%、w(AM)=0.3%、m(改性淀粉)∶m(单体)=1.0∶1.5、m(St)∶m(BA)=2.3∶1.0、引发剂中m(K2S2O8)∶m(NaHSO3)=1.0∶1.0且氧化剂w(K2S2O8)=0.10%时,施胶剂的施胶效果最佳,并且优于传统苯丙乳液施胶剂。     

两种新型水溶性卟啉的合成,表征及其酸碱平衡

以四吡啶基卟啉为中间体合成了四溴化间四(β-N-乙酸乙酯基吡啶基)卟啉(H_2T_(β-_N-_(EAES))-PyPBr_4)和四溴化间四(β-N-丙睛基吡啶基)卟啉(H_2T_(β-_N-_(PCN))PyPBr_4)两种新型水溶性卟啉。产率为77.3～85.0%。作了元素分析、紫外-可见光谱、红外光谱、拉曼光谱、~1HNMR 谱的表征,测量了两种新型水溶性卟啉在水溶液中的酸碱平衡。H_2T_(β-_N-_(BAES))PyPBr_4的浓度约10~(-8)mol/L,在 pH 1～14范围内服从比耳定律,无聚合现象。其 pK_((?)_(3,4))=2.29±0.11;pK_((?)_2)=6.44±0.37;pK((?)_1)=12.38±0.43。H_2T_(β-_N-_(PCN))PyPBr_4的浓度约10~(-5)mol/L,在 pH 1～9范围内不发生聚合,pK((?)_(3,4))=2.90±0.12;当 pH>9时,则发生聚合。     

贵金属修饰型TiO2 的催化活性及Fermi能级对其光催化性能的影响

采用自制纳米TiO2粉末,以磷酸铝为粘结剂,制备了负载型TiO2光催化剂。将Ag,Pt或Pd3种金属的盐溶液滴涂在负载TiO2的表面,从而得到修饰型负载光催化剂(M／TiO2)。通过甲基橙溶液降解实验研究了贵金属的掺杂种类和含量对TiO2光催化性能的影响。实验结果表明：适量掺杂Ag,Pt或Pd3种金属粒子均可提高TiO2的光催化活性,且3种金属粒子的最佳掺杂质量分数分别为0．5％,1．0％和1．0％。在最佳掺杂量时,Ag／TiO2[w(Ag)=0．5％]的光催化活性要高于Pt／TiO2[w(Pt)=1．0％]或Pd／TiO2[w(Pd)=1．0％]。另外,通过金属-半导体接触理论阐述了M／TiO2的光催化机理,并通过Ag,Pt,Pd金属的Fermi能级的不同,解释了Ag／TiO2,Pt／TiO2和Pd／TiO23种光催化剂催化性能的差别。     

Reactivity of Ceramic Superconductors with Palladium Alloys

Palladium alloy compositions were investigated for suitability as a nonreactive material for the processing of ceramic superconductors. Barium-based superconductors were tested on Pd-Au and Pd-Ag alloys for reactivity. Bismuth-based superconductors were tested on a Pd-Ag alloy. The least reactive was found to be 70% Pd-30% Ag for barium-based high-temperature superconductors (HTSC), whereas 30% Pd-70% Ag was found to be least reactive for bismuth-based HTSC.     

Preparation and thermoelectric properties of sulfur doped Ag2Te nanoparticles via solvothermal methods

In this work, n-type Ag(2)Te nanoparticles are prepared by a solvothermal approach with uniform and controllable sizes, e.g. 5-15 nm. The usage of dodecanethiol during the synthesis effectively introduces sulfur doping into the sample, which optimizes the charge carrier concentration of the nanoparticles to >1 × 10(20) cm(-3). This allows us to achieve the desired electrical resistivities of <5 × 10(-6)Ω m. It is demonstrated that Ag(2)Te particles prepared by this solvothermal process can exhibit high ZT values, e.g. 15 nm Ag(2)Te nanoparticles with effective sulphur doping show a maximum ZT value of ~0.62 at 550 K.     

掺杂与Bi系高Tc超导陶瓷的形成

本文探索了Ｂｉ系超导体２２２３相形成时，Ａｌ，Ｃｒ，Ｍｇ和Ｍｎ对高Ｔｃ超导相的形成，结构和超导电性的关系，实验证明，掺杂有利于高Ｔｃ相的形成，有利于提高超导电性。     

Effects of Silver and Palladium Doping on the Dielectric Properties of 0.9Pb(Mg1/3Nb2/3)O3–0.1 PbTiO3 Ceramic

The doping of silver and palladium into a 0.9Pb-(Mg_1/3Nb_2/3)O₃–0.1PbTiO₃ (PMN–PT) ceramic has been investigated. It was found that Ag could be incorporated into the PMN–PT lattice, though this was almost impossible with Pd. Doping at up to 0.2 mol% of Ag and Pd reduced the maximum dielectric constant ( K _max) from 21000 to 14000 without any conspicuous change in physical properties. Order–disorder transitions in the perovskite structure contributed to the decrease in K _max, since the diffuseness parameter, δ, which represents the degree of the order-disorder relationship, increased with Ag doping. However, addition of more than 0.2 mol% increased K _max. Increases in grain size and in the perovskite ratio contributed to this increase. The dielectric properties of Ag/Pd-doped samples were intermediate between the Ag- and Pd-doped samples.     

Sb2O5和Bi2O3添加剂对Ag(Nb1-xTax)O3陶瓷结构、形貌和性能的影响

研究了Sb2O5和Bi2O3添加剂对Ag(Nb1-xTax)O3陶瓷材料的结构、形貌和介电性能的影响.结果表明:当Sb2O5和Bi2O3的质量分数较少(＜2.5%)时,不会影响Ag(Nb1-xTax)O3的钙钛矿结构,但能促进其烧结,使所得陶瓷样品更均匀致密.添加适量的Sb2O5和Bi2O3均可使Ag(Nb1-xTax)O3的介电常数(ε)增大,介电损耗(tgδ)减小,介电性能的温度稳定性得到改善.Bi2O3较Sb2O5对降低Ag(Nb1-xTax)O3陶瓷损耗及改善温度稳定性的效果更佳.     

气固流化床混沌动力结构突变分析

A new method called structural catastrophe analysis was applied to the analysis of pressure fluctuation time series with chaotic and fractal characteristics in gas-solids fluidized bed.In every type of fixed bed,bubbling bed,turbulent bed,fast fluidized bed and pneumatic conveying stage,pressure fluctuation signals were sampled and dynamic exponents were solved.The changes of T_mean and T_max in different types of fluidized bed were analyzed and summarized.It was concluded that T_mean and T_max can indicate different types of fluidized,and T_max can also be recognized as a new characteristic parameter in addition to correlation parameters,LE exponent and K entropy.     

La2O3—AxOy系相图的概括和预测

本文是应用化学键理论概括和预测相图系列研究之一。作者对Dietzel概括相图中的相关规则作了改进,改进的相关性能够解释许多例外;研究讨论了和La_2O_3-A_xO_y系有关的超导陶瓷问题并与最近美国电话电报公司Bell实验室对超导体临界温度的研究作了对比讨论。     

One-pot fabrication of Ag–SrTiO3 nanocomposite and its enhanced thermoelectric properties

Ag–SrTiO₃ ceramic nanoparticles were fabricated by doping SrTiO₃ with various contents (0.5, 1, 3, and 5%, in mass ratio) of Ag. Composite samples were prepared through a one-pot solvothermal method and sintering process. The temperature-dependent thermoelectric properties of these sample were measured from 300 K to 500 K. The maximum power factor (843.3 μ·W/m·K²) at 500 K, which is ∼3.96 times higher than that of the pristine SrTiO₃ ceramics, was obtained for the Ag–SrTiO₃ composite sample with 1% of Ag. In addition, the thermal conductivity of the composites decreased due to the phonon scattering effect. The maximum thermoelectric figure of merit (ZT), i.e., ∼0.09, which was achieved with 1% of Ag at 500 K, yielded an enhanced power factor and a reduced thermal conductivity. This ZT value was ∼4.27 times larger than that of pristine SrTiO₃ at the same temperature.