Cr掺杂对La0.75Ca0.25MnO3陶瓷材料磁性能的影响

采用传统的固相烧结工艺,制备了La0.75Ca0.25Mn1-xCrxO3(x=0,0.02,0.05,0.1)陶瓷样品,用X射线衍射对其微结构进行了分析,并测量了样品的铁磁性能.X射线谱显示样品为四方系晶体.ESR表明掺杂对样品朗德因子g几乎没有影响,而且样品总磁偶极矩的绝大部分是由自旋磁偶极矩贡献的.磁化曲线显示样品存在明显的自旋倾斜态,而掺杂可以削弱甚至破坏样品的自旋倾斜;样品热磁曲线表明,B位高掺杂导致样品晶格畸变从而使得样品磁化强度减小.     

MOCVD生长中载气H2对N掺杂ZnO性质的影响

采用MOCVD方法在石英衬底上生长ZnO。实验使用二乙基锌(DEZn)为锌源,N2O作为氧和氮源,H2作为载气。采用PL和Raman光谱方法对ZnO样品进行表征,结果表明H2的加入大幅度减少薄膜中碳的掺入,明显改善了薄膜的光学质量。采用N2O离化技术,可以进一步提高其带边峰的强度,抑制带内发光。XRD测量表明,生长的ZnO薄膜具有c轴择优取向。目前生长高质量N掺杂的p型ZnO薄膜是很困难的,而H2作为载气的加入明显改善了ZnO薄膜的光学性质,在生长过程中加入H2将为获得高质量N掺杂的p型ZnO薄膜提供一种途径。     

过氧杂多阴离子型层柱化合物的合成、表征及催化活性

通过离子交换法,将含Zr过渡金属离子1,3取代钨硅、钨磷过氧杂多酸盐嵌入Zn2Al类水滑石中,获得了层柱化合物,并用XRD,IR,UV等手段对产物的结构进行了表征.结果表明过氧杂多阴离子进入水滑石层间后,水滑石的层间距从0.92增大到1.47 nm,且过氧链没被破坏.层柱化合物在酯化反应中显示优良的催化性能.     

Al2O3/SnO2 Co-Nanoparticle Modified Grafted Collagen for Improving Thermal Stability and Infrared Emissivity

Al2O3/SnO2 co-nanoparticles were prepared with a modified sol-gel technique followed by a thermal treatment process. With these co-nanoparticles the grafted collagen-Al2O3/SnO2 nanocomposites were obtained using a supersonic dispersion method. X-ray diffraction, FT-IR analysis, transmission electron microscopy, TGA/DTA and infrared emissivity test were performed to characterize the resulting nanoparticles and nanocomposites, respectively. The Al2O3/SnO2 co-nanoparticles showed a narrow distribution of size between 20-40 nm and could be uniformly absorbed on the tri-helix scaffolds of the grafted collagen without any aggregation. The nanocomposites possessed better thermal stability and substantially lower infrared emissivity than the grafted collagen and Al2O3/SnO2 co-nanoparticles with an increase of degradation temperature from 39 to 210 ℃ and a decrease of infrared emissivity from 0.850 of the grafted collagen and 0.708 of the Al2O3/SnO2 co-nanoparticles to 0.424, which provided a potential application of the nanocomposites to areas such as photoelectronics.     

SHAPE MEASUREMENT OF SYNCHROTRON RADIATION WITH HIGH TIME RESOLUTION

By using BWS-5k II streak camera made in China,we have measured the time structure of Synchrotron Radiation (SR) from the relatrivistic electron and positron beam bunches of Beijing Electron Positron Collider (BEPC).The dependence of SR width to the intensity of beam current and the voltage of RF source was also measured.The main data taken with 30ps time resolution in the experiment are as follows: The length of VR at E_e=1.549GeV is changed from 220ps to 670ps when the average beam current from 2mA to 30mA,the variation range of CR length at 20mA beam current is 500—700ps with RF source voltage varying between 250kV and 500kV.The time calibration uncertainty of the experiment is ±15%.The trigger jitter is less than ±200ps.     

过氧杂多阴离子柱撑水滑石的合成、表征及催化性能的研究

通过离子交换法, 将含钛过渡金属离子一、三取代钨硅、钨磷过氧杂多配合物嵌入Zn2Al类水滑石中, 获得了柱撑化合物, 并用XRD, IR, XPS, 元素分析等手段对产物的结构和组成进行了表征。结果表明, 过氧杂多阴离子进入水滑石层间后, 水滑石的层间距从0.92nm增大到1.47nm, 且O2^2^-链没有被破坏。柱撑产物在环己烯氧化反应中显示优良的催化性能。     

大直径高能KrF激光束强度分布实验研究

 利用阵列探测器测出大直径（φ267mm）、高能量（400J）KrF激光束强度空间分布的均匀性和总能量。随着二极管电压的降低, 双向泵浦的束强度空间分布的均匀性变差,甚至成为马鞍型。二极管的最佳工作电压为550～600kV。     

双环氮杂锡氧烷配合物反应性质研究 5: 烷基化反应

首次讨论了双环氮杂锡氧烷配合物与卤代烷的烷基化反应,合成了5种新的双环氮杂锡氧烷配合物,并利用元素分析,IR,^1HNMR,^1^1^9SnNMR以及MS等数据确定了它们的分子结构。     

In-situ Synthesis of ZSM-5 with Different Si/AlRatios on Honeycombshaped Cordierite and their Behavior on NO Decomposition

Thecleaningtechniquestoreduceairpollutionproducedbytheedriaustgasesfromvehicles'enginearefocusedbyresearchworkersinrecentyearsl-2.Amongthem,thecatalyticconversionofthepoisonoussubstances,suchasCO,HCandNOxintonon-orlesspoisonousonesmaybethemosteffective.Thecatalystthatiscalled"monolithiccatalyst"wascomposedofthreepartsfsubstrate,activecoatingandactivecomponents3.Thesubstrateincommonusewasthehoneycomb-shapedcordierite,whosemaincomponentwasfZMgO.ZAI,O,.SSiO,.Theactivecoatings(Y-Al,O,,zeol…     

有电荷转移络合物参与的共聚体系竞聚率

从有电荷转移络合物参与的共聚体系增长基元反应出,提出一种有ＣＴＣ参与的共聚体系竞聚率的求法,从中得到４个竞聚率,自由单体和ＣＴＣ的相对活性等信息。