燃烧剂对低温燃烧合成Pr-CeO2粉体结构与性能的影响

以乙酸铵和柠檬酸为燃烧剂,Ce(NO3)3·6H2O和Pr6O11为主要原料,采用低温燃烧法(LCS)制备了Ce0.95Pr0.5O2纳米晶粉体.用DSC、XRD、SEM及色度测试等手段研究了Ce0.95Pr0.5O2纳米晶微粒前驱体的着火温度、产物晶体结构、晶体形貌及色度.结果表明:乙酸铵和柠檬酸作为燃烧剂的反应前驱体着火温度分别在250℃和300℃左右.两种燃烧产物均为单一的萤石型固溶体.与柠檬酸相比,乙酸铵作为燃烧剂得到的燃烧产物结晶程度更完善、Pr离子进入CeO2晶格的含量更多、呈色更好,且颗粒的团聚程度变小.根据Scherrer公式计算,用两种燃烧剂制备产物的平均晶粒尺寸分别为20～30 nm和10～15 nm,为纳米晶颗粒.最后得到Ce0.95Pr0.5O2粉体的颗粒尺寸则在200～300 nm之间.乙酸铵与硝酸铈的最佳摩尔配比为2:1,柠檬酸与硝酸铈的最佳摩尔配比为3:1.     

用化学溶液方法在Ni-5at%W基底上制备La2Zr2O7过渡层的研究

La2Zr2O7(LZO)过渡层以其独特的物理化学性质越来越受到人们的关注。本文以乙酰丙酮镧和乙酰丙酮锆为前驱盐,丙酸为溶剂配置前驱液,用化学溶液方法(CSD)在具有立方织构的Ni-5at%W基底上制备了LZO过渡层薄膜。研究了前驱液成分、性质以及退火温度对LZO成相以及取向的影响。用常规XRD和X射线四环衍射仪分析了LZO薄膜的相成分和织构。结果显示,在1050℃下退火可以获得强立方织构的LZO薄膜,其中(222)峰的Phi扫描半高宽值为8.95°;(400)峰的Chi扫描半高宽值为6.8°。用高分辨扫描电子显微镜(FE-SEM)观察到LZO薄膜表面均匀致密,没有裂纹和空洞。     

Tailoring Pore Structure and Morphologies in Covalent Organic Frameworks for Xe/Kr Capture and Separation

As a rising star among porous solid materials, covalent organic frameworks(COFs) with excellent properties including but not limit to facilely controllable structure, high porosity, and multi-chemical functionality represent significant potential for efficient ¹²⁷Xe/⁸⁵Kr capture and separation. In this study, through tuning the length of the organic ligands, two-dimensional(2D) COF mate-rials with identical connection group but different pore properties, denoted as ATFG-COF and TpPa-COF with AA-stacking model and TpBD-COF with AB-stacking model were synthesized and tested for Kr and Xe adsorption for the first time. Adsorption measurements indicate that the narrower pore apertures and higher porosity are conducive for COF materials to capture Xe and Kr. Furthermore, the Henry's constant, isosteric heat of adsorption(Q_st), and ideal adsorbed solution theory(IAST) selectivity of ATFG-COF, the pore size of which is closest to the kinetic diameter of the Xe atom(0.41 nm) among 2D COF materials, were carried out based on the single component sorption isotherms. The results illustrate that the high isosteric heat values of Xe/Kr adsorption on ATFG-COF are 25 and 16 kJ/mol at room temperature, respectively. Henry's law predicts that the selectivity factor of Xe to Kr is 6.07, consistent with the adsorption selectivity(ca. 6) calculated based on the IAST.     

光纤耦合数码系统传像特性

建立了光纤传像元件与光电阵列器件的匹配耦合模型,引入变动因子反映像素光纤排列的不确定性,进行了光纤耦合传像特性的仿真研究.针对9×9 μm2光敏元的阵列器件,分析了光纤传像元件结构参数变化对系统分辨率的影响,在光纤直径约为光敏元尺寸1/3时获得了相对经济合理的匹配结构,表明光纤耦合数码系统设计时必须考虑优化匹配问题.仿真结果还解释了系统的图像输出存在条纹和局部结构背景的原因,给出了相应的数值分析方法.     

DISSOLUTION OF IRON TO COPPER IN Fe60Cu40 ALLOY BY MECHANICAL ALLOYING AND SUBSEQUENT DECOMPOSITION

A metastable alloy with composition Fe₆₀Cu₄₀ can be prepared in single phase of a fcc structure by mechanical alloying, although Fe-Cu system is virtually immiscible in its equilibrium state at ambient temperature. The M?ssbauer spectra of this supersaturated solid solution could be fitted by two subspectra whose hyperfine magnetic fields are 200 kOe and 250kOe. In this metastable alloy, the iron atoms at the interface are easy to form clusters characterized as α-Fe at a temperature below 250℃, whereas the iron atoms in the body will cluster together at a higher temperature above 350℃ and behave as γ-Fe, and then transform to ferromagnetic bcc iron occurs.     

High-order squeezing of pure superposition states

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Study of Intramolecular Cyclization of N-styryl-oxo-cinnamides (Ⅱ)

lnthepreviouspaper',wereportedtheintramolecularcyclizationsofamide4anditscis-eneisomerinanattempttosynthesizehomoclausenamideandzetaclausenamide2.Inordertostudytherelationshipbetweenthestereochemistryandtheilltramolecularcyclizationofthisseriesofcompounds,theamides5(cis-oxirane,trans-ene)and8(cis-oxirane,cis-ene)wereprepared,andtheirintramolecularcyclizationswerereportedinthispaper.Theamide5withm.p.152.O-l54.O"CwasobtainedfromDarzen'scondensationofcompound3withPhCHOinMeOHatl5-2OoCwithMeO…     

二阶拟线性椭圆型方程振动性的积分平均方法

§ 1.　IntroductionThepurposeofthispaperistostudytheoscillatorybehaviorofsolutionsofcertainquasi linearellipticequationsdiv( ｜Du｜m -2 A(x)Du) + p(x) ｜u｜m -2 u=0 ,x∈Ω Rn,(E)whereΩisanexteriordomain ,m >1 ,andfunctionsA(x) ,p(x)aretobespecifiedinthefollowingtext.Recently ,USAMI [6]consideredEq .(E)whenA(x)≡I (identitymatrix) ,andob tainedoscillationcriteriaforEq .(E)with“infiniteintegral”coefficient [cf.[6],Theorem 4].However,asfarasthepresentreferencesisconcerned ,therearefewo…     

碰撞电离产生Au L3空穴态定向行为的研究

采用一种简单的实验方法测定低能区几种离子与Ａｕ碰撞产生Ａｕ的Ｌ₃空穴态的定向度，及定向度的入射离子能量相关性；同时在平面波玻恩近似理论基础上加上库仑偏转效应的校正进行了理论计算，改善了实验点与平面波玻恩近似理论计算的符合程度，讨论了有关空穴态定向行为。 关键词：     

弹性结构封闭空间有源消声

本文研究了外力激励弹性结构条件下封闭空间有源消声问题。首先根据声弹性理论,提出分步代入法求解初、次级声场,然后以矩形空间为例,研究了不同介质条件下有源消声规律。结果表明:对于弹性结构封闭空间有源消声,当结构一声腔耦合较弱时,次级声源基本上只能抵消声腔模态;当结构一声腔耦合较强时,次级声源不仅能抵消声腔模态,而且对抵消与声腔模态耦合良好的结构模态辐射声也有作用。最后,以有限长圆柱封闭空间为模型,完成了结构受点力激励,腔内为空气介质和水介质条件下的单次级声源有源消声实验。验证了理论结果。