低温燃烧法制备纳米Ce1-xNdxO2-x/2(0≤x≤0.6) 粉体的研究

采用低温燃烧合成工艺，在甘氨酸-硝酸盐体系下制备出纳米Ce1-xNdxO2-x/2(0≤x≤0．6)系列粉体(NDC)。X射线衍射(XRD)结果表明。Nd^3 取代Ce^4 进入晶格内部，形成具有单相立方萤石型结构的固溶体，其晶格常数随Nd^3 掺杂浓度的增大而线性增加，晶粒尺寸在17～28nm之间。透射电镜(TEM)结果表明，粉体尺寸在30-40nm之间，具有较高的烧结活性。拉曼光谱(Rman spectrum)表明％宽化峰与掺杂后固溶体中产生的氧空位有关。     

弱磁场下低温中和法制备亚微米非晶态δ-FeOOH的研究

利用XRD和SEM分别对在弱磁场下通过低温中和法制备的羟基铁氧化物进行相成分和颗粒形貌分析. 试验结果表明: 无磁场下, 产物是由部分球形和部分针状的α-FeOOH组成. 0.1 T磁场下, 产物是纺锤形的γ-FeOOH, 但是, 其粒度分布很不均匀. 0.3 T磁场下, 产物是球形的Fe_1.833(OH)_0.5O_0.25. 0.5 T磁场下, 产物是100 nm左右的球形的非晶态δ-FeOOH. Fe_1.833(OH)_0.5O_0.25是无磁场下制备的α-FeOOH向弱磁场下制备的δ-FeOOH转变的中间产物. 并且, 亚微米球形Fe_1.833(OH)_0.5O_0.25和亚微米非晶态球形δ-FeOOH的粒度分布都很均匀. 此外, 弱磁场影响羟基铁氧化物的结晶度.     

N-对甲基苯基-N′-（2-吡啶基）脲的低温热容及热分析

通过低温量热和热分析方法,测定了N-对甲基苯基-N′-（2-吡啶基）脲(以下简称NPMPN′2PU)的低温热容和热力学性质.通过对NPMPN′2PU进行低温量热,得到了NPMPN′2PU在80～370 K 温区的热容曲线,热容曲线光滑,没有任何热异常现象,由此实验热容数据计算出NPMPN′2PU在这段温区内的热力学数据.从DSC实验结果发现, NPMPN′2PU熔化峰值出现在173.86 ℃,熔化焓为204.45 kJ•mol－1.紧接熔化峰后NPMPN′2PU开始分解,分解峰只有一个,分解峰值温度为226.11 ℃.TG和DTG的实验结果表明,NPMPN′2PU失重的峰值为227.2 ℃,这些结果与DSC实验结果吻合.     

ZnS纳米粒子的固相合成及其光学性能

将不同的添加剂引入到低温固相反应中，快速合成了不同尺寸的ZnS纳米粒子。利用TEM表征了产物形貌，利用XRD研究了不同的添加剂、同一添加剂下不同的反应温度、不同反应时间对纳米粒子尺寸的影响。结果表明，不同的添加剂对粒子的尺寸影响较大，其中，十二烷基胺以其特殊的反应方式在较高温度下获得了较小的纳米粒子。另外，在PEG400存在条件下，反应温度和反应时间对粒子尺寸均有一定的影响。同时，对不同条件下所得产物的紫外-可见光吸收性能也进行了测试。     

Zn-CCl2F2-H2O体系的低温基质隔离化学反应

低温基质隔离技术与各种光谱技术相结合,作为研究活性分子、分子结构、催化、光化学和制备新物质的一种重要方法,在国外已相当普遍,特别是在无机低温制备方面,由于涉及金属原子的低温化学反应具有简单性和自发性两大优点,近十多年来已有很大发展,专家们预言,低温无机合成化学,二十年后将成为一种重要的合成方法.目前国内尚未见有报道,本文介绍我们在这方面的初步尝试.     

邻乙氧基苯甲酸的氢键模式随温度的变化关系

晶体中邻甲氧基苯甲酸以分子间氢键形成的二聚体形式存在,但邻乙氧基苯甲酸却以分子内氢键形成的单体存在.本文用低温红外光谱,结合氘代和酰氯化实验揭示了邻乙氧基苯甲酸晶体中也存在二聚体,但室温时含量很少,随着温度降低,含量逐渐增加.     

新型阴极材料Ba0.5Sr0.5Co0.8Fe0.2O3-σ制备与性能研究

Ba_0.5Sr_0.5Co_0.8Fe_0.2O_3-σ(BSCF), a new cathode material for solid oxide fuel cell (SOFC), was synthesized by polyacrylicacid (PAA) method. The lattice structures of samples calcined at different temperatures were characte-rized by XRD. Shrinkage, porosity and pore size of the porous BSCF as a function of sintering temperature were investigated. It was found that the cubic perovskite structure could be formed after calcination at 800 ℃ for 2 h, but not well crystallized as seen from some unknown phases, and the pure cubic perovskite structure was formed after calcination at 1 150 ℃ for 2 h. The particle size of BSCF was less than 1～2 μm. The shrinkage of the porous BSCF increased with sintering temperature, but the opposite was true for the porosity. After sintering at 1 100 ℃ for 4 h, the porous BSCF was still in an appropriate structure, with porosity of 29% and electrical conductivity above 400 S·cm^-1.     

Low-Temperature Heat Capacities and Thermodynamic Properties of Octahydrated Barium Dihydroxide,Ba（OH）2·8H2O（s）

Low-temperature heat capacities of octahydrated barium dihydroxide, Ba（OH）2·8H2O（s）, were measured by a precision automated adiabatic calorimeter in the temperature range from T=78 to 370 K. An obvious endothermic process took place in the temperature range of 345-356 K. The peak in the heat capacity curve was correspondent to the sum of both the fusion and the first thermal decomposition or dehydration. The experimental molar heat capacifies in the temperature ranges of 78-345 K and 356-369 K were fitted to two polynomials. The peak temperature, molar enthalpy and entropy of the phase change have been determined to be （355.007±0.076） K, （73.506±0.011） kJ·ol^-1 and （207.140±0.074） J·K^-1·mol^-1, respectively, by three series of repeated heat capacity measurements in the temperature region of 298-370 K. The thermodynamic functions, （Hr-H298.15 k ）and （Sr-S298.15k）, of the compound have been calculated by the numerical integral of the two heat-eapacity polynomials. In addition, DSC and TG-DTG techniques were used for the further study of thermal behavior of the compound. The latent heat of the phase change became into a value larger than that of the normal compound because the melfing process of the compound must be accompanied by the thermal decomposition or dehydration of 71-120.     

低温陈化法制备SO42-/ZrO2-TiO2超强酸及其催化性能和稳定性研究

本文采用低温陈化法制备了SO₄^2-/ZrO₂-TiO₂固体超强酸,并将其用于催化乙酸正丁酯的酯化反应,采用TEM、IR和XRD等对样品进行了检测。结果表明,低温陈化的样品具有较强的酸性和催化活性,空气中放置30天后其酸性和催化活性变化不大。XRD谱图显示,低温陈化的样品经550℃焙烧后出现了较强的锐钛矿晶相衍射峰。     

氯化钐与甘氨酸配合物Sm(Gly)2Cl3·3H2O热化学研究

A complex of samarium with glymine， [Sm(Gly)₂Cl₃·3H₂O]， was synthesized and characterized by DSC， TG and DTG. A possible mechanism of thermal decomposition of this complex was suggested. The heat capacities of the complex were measured by a precision adiabatic calorimeter over the temperature range from 82 to 375 K. The solution enthalpies of reactants [SmCl₃·6H₂O+2Gly] and the products [Sm(Gly)₂Cl₃·3H₂O+3H₂O] were determined by an isoperibel solution- reaction calorimeter at 298.15 K， respectively; the standard molar enthalpy of formation of [Sm(Gly)₂Cl₃·3H₂O] was calculated through a designed thermochemical cycle.