碳酸氢铵沉淀法制备氧化钇粉体时反应条件对产物粒度的影响

研究了碳酸氢铵沉淀法的反应条件对氧化钇粒度的影响,探讨了粒度变化规律。发现在沉淀反应中,晶型碳酸钇铵的形成与否是影响氧化钇粒度的关键因素。在较低的反应温度下,当碳酸氢铵和氯化钇的浓度大于0.25mol·L-1,摩尔比大于5,陈化时间大于60min时得到碳酸钇铵沉淀,经煅烧可获得粒度(D50)大于1μm的氧化钇。当反应物浓度较低、摩尔比小,陈化时间较短时得到无定型碳酸钇沉淀,煅烧沉淀可获得粒度(D50)小于0.5μm的氧化钇。实验证明选择适当的沉淀反应条件,可制备D50在0.3～10μm范围内的不同粒度级别的氧化钇粉体。     

聚（3—丁基噻吩）电导的热稳定性

研究了导电聚合物聚（３－丁基噻吩）（ＰＢＴ）在大气环境下的导电热稳定性。在室温至２２０℃范围内，测试电导率随时间及温度的变化。ＴＧＡ分析以及化学分析的结果表明：掺杂态的ＰＢＴ大约在１４０℃附近有一转化温度，低于或高于这一转化温度，电导率下降的决定因素各不相同。高于转化温度时，电导率下降的主要原因是反离子和高分子主链的解离，进而发生化学反应，影响了高分子主链的结构。ＸＰＳ测试结果表明：经热处理后的Ｐ     

辐照聚甲醛聚合机理、结构与形态的研究——Ⅱ.三聚甲醛单晶辐照引发固相聚合产物的亚微观结构

三聚甲醛单晶经Co_(60)γ射线辐照可以得到一种结晶度很高的聚三聚甲醛。在辐照聚合制得的聚三聚甲醛的迴转图上,除出现普通聚甲醛的衍射点外,还存在着一些新的衍射斑点。 聚三聚甲醛沿着原来三聚甲醛的c轴可以劈成纤维,在迴转图中新的衍射斑点,当样品加温处理后会逐渐消失。 比较聚甲醛与三聚甲醛分子所占的空间,我们认为:聚甲醛确有四种不同取向的晶区,它们联结在一起形成许多曲棍状的微晶。     

Tree-gel and loop-gel conversions in nonlinear polymerization

Ａｓｉｓｗｅｌｌｋｎｏｗｎ,ｔｈｅｔｈｅｏｒｙｆｏｒｎｏｎｌｉｎｅａｒｐｏｌｙｍｅｒｉｚａｔｉｏｎｓｗａｓｉｎｉｔｉａｔｅｄｂｙＦｌｏｒｙａｎｄＳｔｏｃｋｍａｙｅｒ[1—3].ＭｉｌｌｅｒａｎｄＭａｃｏｓｋｏ[4—6]ｐｒｏｐｏｓｅｄａｒｅｃｕｒｓｉｖｅｍｅｔｈｏｄｆｏｒｄｅａｌｉｎｇｗｉｔｈｔｈｅｐｒｏｂｌｅｍｏｆｔｈｅｐｏｓｔｇｅｌｐｒｏｐｅｒｔｉｅｓｏｆｔｈｅｎｅｔｗｏｒｋｆｏｒｍｉｎｇｐｏｌｙｍｅｒｉｚａｔｉｏｎ.Ｓｔｅｐｔｏ[7]ｉｎｖｅｓｔｉｇａｔｅｄｔｈｅｇｅｌｇｅｌｒｅａｃｔｉｏｎｏｆＲＡｆｔ…     

萃取动力学光度法测定活化剂铝——铝(Ⅲ)-过氧化氢-铜(Ⅱ)-邻氨基酚/氯仿体系

研究了在pH 5.5的弱酸性介质中, 利用Al(Ⅲ)对Cu(Ⅱ)催化H2O2氧化邻氨基酚显色的指示反应的活化作用.用萃取平衡控制反应时间、水相中邻氨基酚的浓度和反应进行的程度.通过在424 nm下测量有机相的吸光度,建立了萃取催化光度法测定活化剂铝的新方法.方法的线性范围为0.004～0.25 mg/L,检出限为1.6×10 -6 g/L.用于水样和茶叶中铝含量的测定,结果满意.     

Designed nanostructured pt film for electrocatalytic activities by underpotential deposition combined chemical replacement techniques

Multiple-deposited Pt overlayer modified Pt nanoparticle (MD-Pt overlayer/PtNPs) films were deliberately constructed on glassy carbon electrodes through alternately multiple underpotential deposition (UPD) of Ag followed redox replacement reaction by Pt (II) cations. The linear and regular growth of the films characterized by cyclic voltammetry was observed. Atomic force spectroscopy (AFM) provides the surface morphology of the nanostructured Pt films. Rotating disk electrode (RDE) voltammetry and rotating ring-disk electrode (RRDE) voltammetry demonstrate that the MD-Pt overlayer/PtNPs films can catalyze an almost four-electron reduction of O(2) to H(2)O in air-saturated 0.1 M H(2)SO(4). Thus-prepared Pt films behave as novel nanostructured electrocatalysts for dioxygen reduction and hydrogen evolution reaction (HER) with enhanced electrocatalytic activities, in terms of both reduction peak potential and peak current, when compared to that of the bulk polycrystalline Pt electrode. Additionally, it is noted that after multiple replacement cycles, the electrocatalytic activities improved remarkably, although the increased amount of Pt is very low in comparison to that of pre-modified PtNPs due to the intrinsic feature of the UPD-redox replacement technique. In other words, the electrocatalytic activities could be improved markedly without using very much Pt by the technique of tailoring the catalytic surface. These features may provide an interesting way to produce Pt catalysts with a reliable catalytic performance as well as a reduction in cost.     

间位取代四苯基卟啉铁(Ⅲ)的紫外可见光谱及其与二乙胺轴配反应的研究

研究了二氯甲烷溶液中二乙胺(L)与氯合(meso-四-间甲基苯基卟啉)铁(Ⅲ)的轴向配位反应.用光谱法测得不同温度下反应的平衡常数,求得(m-CH₃)TPPFe(Ⅲ)Cl+L=(m-CH₃)TPPFe(Ⅲ)Cl·L反应的标准摩尔焓和摩尔熵.同时,对反应的动力学与反应机理进行了研究.也研究了反应物和产物的紫外可见光谱,并讨论了取代基及轴向配体对铁卟啉紫外可见光谱的影响。     

Synthesis and Crystal Structure of （Et4N）2[Pd2（mp）2（mpH）2]

ＳｙｎｔｈｅｓｉｓａｎｄＣｒｙｓｔａｌＳｔｒｕｃｔｕｒｅｏｆ（Ｅｔ_４Ｎ）_２［Ｐｄ_２（ｍｐ）_２（ｍｐＨ）_２］ＳｈｉＪｉ－Ｃｈｅｎｇ；ＨｕａｎｇＸｉａｏ－Ｙｉｎｇ；ＷｅｎＴｉｎｇ－Ｂｉｎ；ＤｅｎｇＹｕ－Ｈｅｎｇ；ＣｈｅｎｇＣｈａｎｇ－Ｎｅｎｇ；Ｌｉ?..