Sr_2CeO_4物相形成过程的XRD分析

采用X射线衍射技术分析了SrCO3和CeO2 (摩尔比 2∶1 )混合粉料经不同灼烧时间反应后的物相组成 .结果表明在Sr2 CeO4的形成过程中将出现不稳定的中间相SrCeO3,原始粉料CeO2 相会提前消失 ,SrCeO3与SrCO3反应生成最终稳定的目标相Sr2 CeO4.X射线衍射数据显示Sr2 CeO4属正交晶系     

SrF2颗粒涂覆增强Si/C负极电化学性能

The silicon-based material exhibits a high theoretical specific capacity and is one of the best anode for the next generation of advanced lithium-ion batteries (LIBs). However, it is difficult for the silicon-based anode to form a stable solid-state interphase (SEI) during Li alloy/de-alloy process due to the large volume change (up to 300%) between silicon and Li_4.4Si, which seriously limits the cycle life of the LIBs. Herein, we use strontium fluoride (SrF₂) particle to coat the silicon?carbon (Si/C) electrode (SrF₂@Si/C) to help forming a stable and high mechanical strength SEI by spontaneously embedding the SrF₂ particle into SEI. Meanwhile the formed SEI can inhibit the volume expansion of the silicon?carbon anode during the cycle. The electrochemical test results show that the cycle performance and the ionic conductivity of the SrF₂@Si/C anode has been significantly improved. The X-ray photoelectron spectroscopy (XPS) analysis reveals that there are fewer electrolyte decomposition products formed on the surface of the SrF₂@Si/C anode. This study provides a facile approach to overcome the problems of Si/C electrode during the electrochemical cycling, which will be beneficial to the industrial application of silicon-based anode materials.     

甲烷氧化偶联催化剂和部分氧化反应机理的原位及非原位谱学表征

采用原痊红外和原位显微Raman光谱技术及XPS、吡啶（Py)吸附的漫反射UV谱、Py-TPD、CO2-TPD等方法对含氟稀土基催化剂上甲烷氧化偶联（OCM）反应活性氧物种、催化剂表面酸碱性进行了考察。在O2预处理和/或工作条件下的SrF2/La2O3,SrF2/Nd2O3,LaOF,BaF2/LaOF和BaF2/CeO2等催化剂上原位观测到超氧物种（O2^-),并在其中前4种催化剂上检测到O2^-物种与CH4反应生成的气相C2H4,CO2和表面碳酸盐等OCM反应主、副产物。这些结果为O2^-是相应催化剂上OCM反应的活性氧物种首次提供了直接的光谱证据。研究结果表明,催化剂的OCM反应性能与其表面酸碱性的强弱并无简单的对应关系。采用原拉时间分辨红外光谱和原位显微Raman光谱技术对SiO2和γ-Al2O3负载的Rh、Ru催化剂上甲烷部分氧化（POM）制合成气反应的研究表明,由CH4直接氧化生成CO和H2是Rh/SiO2上POM反应的主要途径,而燃烧-重整机理是Ru/γ-Al2O3和Ru/SiO2上CO和H2生成的主要途径,反应条件下催化剂表面氧（O^2-)物种浓度的差异很可能是导致这两种催化剂体系上POM反应机理不同的主要原因,其本质可能源于Rh和Ru对氧的亲合力的不同。     

富马酸根插层的MgAl-LDH对水性环氧树脂涂层耐腐蚀性能的提升作用

使用超重力技术制备了富马酸根插层的镁铝层状双氢氧化合物(LDH-Fu)浆液，经水热处理后得到LDH-Fu粉末。利用X射线衍射仪(XRD)、傅里叶变换红外光谱仪(FT-IR)、X射线光电子能谱仪(XPS)及场发射扫描电子显微镜(FESEM)对LDH-Fu粉末进行了表征，结果表明与NO₃^-插层的LDH(LDH-NO₃^-)相比，LDH-Fu呈现出更加规则的六边形，并且分散性也更好。测试了富马酸根在0.01 mol/L NaCl溶液中从LDH层间释放的速度，结果表明LDH-Fu能对腐蚀性离子做出快速响应，并且能保持长时间的释放。将一定量的LDH-Fu添加到水性环氧树脂中，涂布在马口铁样板上，通过浸泡试验和盐雾试验测试了水性涂层的耐腐蚀性能，结果表明：在LDH-Fu添加量为0~7% (质量分数)的范围内，添加3% LDH-Fu的水性涂层具有最佳的防护性能；与添加3% LDH-NO₃^-相比，添加3% LDH-Fu的水性涂层具有更好的耐腐蚀性能。     

BaCeO3和SrCeO3基钙钛矿型固体电解质

综述了ＢａＣｅＯ３基和ＳｒＣｅＯ３基钙钛矿型固体电解质,从结构、不同气氛中导电性方面进行了介绍,对其应用方面进行了较为详细的分析。在燃料电池、电解池、薄膜反应器、气体传感器等方面的应用分析表明这２类固体电解质有广泛的应用前景。     

金属粉末注射成形用石蜡-油-聚乙烯粘结剂

研制了用于Fe-2Ni粉末注射成形的石蜡-油-聚乙烯粘结剂,选择了石蜡和聚乙烯组分,考察了油的加入对组分相容性、生坯强度、粉末装载量、喂料比热容、溶剂脱脂速率的影响.实验结果表明石蜡-油-聚乙烯粘结剂是热力学不相容的体系;油的加入降低了混炼扭矩、最大粉末装载量和生坯强度,但同时也减少了注射缺陷,并使溶剂脱脂速率增大;加入该粘结剂,可使Fe-2Ni粉末装载量(体积分数)达60％,生坯强度达5.5MPa,溶剂脱脂速率大于2mm/h.     

Characteristics of tidal gravity changes in Lhasa, Tibet, China

Tidal gravity changes arise from the response of the solid Earth to the tidal forces of the Sun,Moon and planets close to the Earth,and are a comprehensive reflection of the structure and distribution of physical properties of the Earth’s interior.As a result,observations of tidal gravity changes are the basis of studies on other global and/or regional dynamic processes.The characteristics of tidal gravity changes in the region of the Tibetan Plateau were investigated through continuous gravity measurements recorded with a superconducting gravimeter (SG) installed in Lhasa over a year.Through contrast measurements with a spring gravimeter LaCoste-Romberg ET20 at the same site,the gravity observations in Lhasa were scaled to the international tidal gravity reference in Wuhan.Meanwhile,the scale factor of the SG was determined accurately as-777.358 ± 0.136 nm s-2V-1,which is about 2.2% less than the value provided by the manufacturer.The results indicate that the precision of the tidal gravity observations made with the SG in Lhasa was very high.The standard deviation was 0.459 nm s-2,and the uncertainties of for the four main tidal waves (i.e.O 1,K 1,M 2 and S 2) were better than 0.006%.In addition,the observations of the diurnal gravity tides had an obvious pattern of nearly diurnal resonance.As a result,it is affirmed that the Lhasa station can provide a local tidal gravity reference for gravity measurements on the Tibetan Plateau and its surrounding regions.The loading effects of oceanic tides on tidal gravity observations in Lhasa are so weak that the resulting perturbations in the gravimetric factors are less than 0.6%.However,the loading effects of the local atmosphere on either the tidal or nontidal gravity observations are significant,although no seasonal variations were found.After removal of the atmospheric effects,the standard deviation of the SG observations in Lhasa decreased obviously from 2.009 to 0.459 nm s-2.Having removed the loading effects of oceanic tides and local atmosphere,it was found that the tidal gravity observations made with the SG in Lhasa significantly differed by about 1% from those expected theoretically,which may be related to active tectonic movement and the extremely thick crust in the region of the Tibetan Plateau.A more-certain conclusion requires longer accumulation of SG data and further associated theoretical studies.     

超重力法制备超细二氧化硅及影响因素的研究

以水玻璃和硫酸为原料,在超重力反应器中采用沉淀法合成了超细二氧化硅粉体。探讨了反应pH值、陈化作用、旋转床转速等因素对二氧化硅性能的影响规律。研究结果表明：超重力环境不仅可以使沉淀反应时间大大缩短,而且有利于生成粒径小、比表面积大的超细二氧化硅产品;确定了最佳制备工艺条件为反应终点pH值2～3、陈化时间60～90min、旋转床转速800～1000r/min。     

超重力场辅助燃烧合成技术制备Fe3Al合金及其抗氧化性能研究

本课题利用超重力场辅助的两步燃烧合成技术成功制备了Fe3Al合金.首先利用Al/Fe2O3之间的铝热反应释放的高热量使得产物(Fe和Al2O3)转变成高温混合熔体,Fe熔体在1000 g超重力场的作用下迅速从高温混合熔体中分离,并和底部的纳米铝粉发生二次燃烧合成,生成致密的Fe3Al金属间化合物.Fe3Al样品中仅存在...     

纸张大变形非线性有限元分析

根据虚功原理和薄板度理论,对纸张在自重作用下的静动力学特性作了非线性有限单元法数值建模。就纸张大变形问题给出了几何非线性增量格式更新拉格朗日描述,编制了2D有限元计算程序,并采用Newton-Rephson迭代法对送纸过程中纸张的大幅弯曲垂落进行数值分析。计算结果表明,此法计算量小、精度高,二维结果优于一维结果,与实测值相当吻合,适用于分析纸张的机械特性。