Modified Pechini Synthesis of Proton‐Conducting Ba(Ce,Ti)O3 and Comparative Studies of the Effects of Acceptors on its Structure,Stability, Sinterability,and Conductivity

The phase structure, chemical stability, sinterability, and electrical performance of the proton‐conducting Ba(Ce,Ti)O₃ solid solution with a series of acceptors M (M = In, Y, Sm) synthesized by a modified Pechini method were systematically investigated. The substitution of cerium with titanium was proved as an effective way to improve the stability of BaCeO₃. Especially for the BaCe_0.95Ti_0.05O_3?δ sample doped with In, no change in the phase was found even after treatment in the atmosphere containing both CO₂ and H₂O at 700°C for 10 h. Thanks to the highly sinteractive powders with particle size of ~100 nm, dense ceramics were easily acquired. Moreover, compared with the undoped BaCe_0.95Ti_0.05O₃ sample, In, Y, and Sm dopants further improved the sinterability of the solid solution. In particular, In played a role of sintering aid and led to the largest linear shrinkage of the ceramics. As to the electrical performance, the transport properties of the samples under various atmospheres were analyzed and compared. The impedance tests demonstrated the best electrical performance of the Y‐doped samples.     

A New Ferroelectric Phase of YMnO3 Induced by Oxygen‐Vacancy Ordering

Manganese oxides are good candidates of strongly correlated electron materials due to the uniqueness of electronic structure of manganese and the mobility of oxygen among lattice sites under external impacts. Here, we used electron beam as the excitation source to explore the structural evolution of YMnO₃ and identified a new phase under the radiation of electron beam in the transmission electron microscope. Analyses of the electron energy‐loss spectra reveal that this phase originates from ordered oxygen vacancy. We applied the first principles calculation to pick out the optimized stable structure with a lower polarization, and verified its correctness by electron diffraction and image simulations. Analyses of density of states indicate that weak Y–O covalence is favorable for the existence of ferroelectricity, supporting the electrostatic nature of ferroelectricity in the YMnO₃.     

混合溶剂芳脂比与特定温度下密度的关系

为提高生产效率、降低生产成本、快速判断混合溶剂芳脂比,研究了混合溶剂芳脂比与特定温度下密度的关系。实验结果表明,混合溶剂的芳脂比与其特定温度下的密度之间存在明显线性关系,且该线性关系对生产具有指导意义。     

Alkaline activation of coals and carbon-base materials

Data on the reactions and processes occurring under the conditions of the alkaline activation of carbon substances—the production of activated carbons by the thermolysis of carbon substances in the presence of alkali metal hydroxides MOH—are summarized. The following most important activation processes were recognized: (1) the interaction of functional groups with MOH and the formation of intermediate structures with the C-O-M group; (2) their conversion into metal-containing compounds (primarily, M₂CO₃ and M₂O) in reactions with carbon, especially, with terminal C atoms on the periphery of graphenes; and (3) the reduction of M₂CO₃ and M₂O to the metal M, which is intercalated into the interlayer spaces of crystallites. The mechanism of alkaline activation was studied in most detail for KOH as an activating agent. The thermally initiated reduction of potassium oxide with carbon and the intercalation of potassium metal are the two most important processes for the development of the microporosity of activated carbon.     

降低介耗 提高精煤产率

针对河南禹州地区煤质煤泥含量高、浮选精煤粒度组成过细、细粒级颗粒偏多等极难选特征,为了优化极难选高细泥含量原煤洗选加工工艺、提高精煤产率、降低介耗,河南永锦选煤有限公司通过应用3GDMC1100/780AI型无压给料三产品重介旋流器,采取提高精煤产率措施与降低介耗途径,实现精煤产率提高2%,原煤介耗由2.5 kg/t降至1.21 kg/t,降低了材料消耗,增加经济收益1 347万元。     

Refractory Ceramic Fiber and the Products GB/T 3003-2006

正GB/T 3003-20061 Scope This standard specifies the terms,definitions,classifications,brands,technical requirements,test methods,quality appraisal procedure,packing,marking,transportation,storage and quality certificate of     

中专化学“复习方法”初探

根据教材特点和教学对象的特性,采用行之有效的"化学复习方法",既可提高学生的学习效率也能增强学生的学习兴趣。从而进一步提高中专生的综合能力和专业素质。     

Hydrogenated silicon oxycarbonitride films. Part II. Physicochemical and functional properties

The optical, and electrophysical characteristics of hydrogenated silicon oxycarbonitride films synthesized by the plasma enhanced chemical vapor decomposition of the mixtures of 1,1,1,3,3,3-hexamethyldisilazane with oxygen and nitrogen in the temperature range of 373–973 K have been studied. It has been shown that the obtained films are highly transparent (transmittance is ～92–99%) in the UV, visible, and IR ranges of the spectrum; they have refractive indices in the range of 1.43–2.25, a low reflection coefficient of visible light (nearly 3%), and low dielectric permittivity.     

Preparation and Characterization of C10–C14 Alkyl Cellulose Ester Sulfate Surfactant

The aim of this work is to synthesize surfactants based on cellulose with different molecular weights. Raw cotton cellulose was tailored into cellulose segments with different molecular weights by a hydrothermal process, then the average degree of polymerization (DP) was determined by viscosimetry and the molecular weight distribution was estimated by gel permeation chromatography. The C₁₀–C₁₄ alkyl cellulose ester sulfate surfactants were prepared by hydrophilic sulfonation and hydrophobic esterification. The surface tension of the surfactants solution was obtained by the Wilhelmy plate method. Results showed that the cellulose segments presented a broader distribution compared with the raw material. The critical micelle concentration (CMC) value decreased from 1.08 to 0.86 wt% as the hydrophobic chain length was increased from 10 to 14. The CMC values of cellulose surfactants with C₁₄-acyl chloride hydrophobization decreased from 1.32 to 0.86 wt% as the DP was decreased from 2,700 to 296.