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151.
小分子在聚四氟乙烯上吸附的量子化学研究Ⅱ.聚四氟乙烯—H_2、O_2、CO和CH_4体系刘尚长,马玉满,高扬,姜莉(辽宁大学化学系)(沈阳进出口商贸检局)关键词聚四氯乙烯;分子簇络合物;吸附共吸附;CNDO/2方法;掺杂聚合物各种构象的线性聚合物的相对?.. 相似文献
152.
应用本组改进加速的CNDO/2量子化学方法计算和确定了GeCl2及其掺杂聚吡咯络合物的结构参数,从而给出了稳定形态的电子结构,比较合理的解释了成键情况,并对其络合物(PPGC)的合成和应用价值进行了理论上的评估,对以往仅是Lewis酸阴离子掺杂的看法,提出了重要的补正。此类研究尚未见报道。 相似文献
153.
马全喜 《河北大学学报(自然科学版)》1992,(2)
本文从电子占据能级的几率出发,经过严格数学推导,得到了杂质半导体的电离率、电离能、浓度及温度各量关系的一般表达式,并与某些极端条件下的近似结果进行了比较。分析表明,本文得到的表达式具有普遍意义,该关系式对于分析上述各量关系,特别是在非极端条件下,具有实际意义。 相似文献
154.
Investigations have been made on luminescence properties of copper-doped CdSe nanoparticles, synthesized via green chemical route. The nanoparticles remain stable under normal atmospheric conditions and can be redispersed in suitable solvents (water and dimethyl formamide). The photoluminescence peak positions in the copper doped CdSe nanoparticles are found to strongly depend on the copper ion concentration. Under UV irradiation visible luminescence covering the entire visible range has been observed. 相似文献
155.
S. Jandl A.A. Mukhin V. Yu Ivanov A. Balbashov M. Orlita 《Journal of magnetism and magnetic materials》2009,321(21):3607-3610
Nd3+ crystal-field excitations in Nd1−xCaxMnO3 (x=0.025, 0.05 and 0.1) single crystals are studied via infrared transmission as a function of temperature and external magnetic field. We report excitations associated with Nd3+ sites as detected in NdMnO3 and excitations due to Ca doping. The latter reveal phase separation between the usual A-type antiferromagnetic states and the insulating canted (ferromagnetic) spin states in the vicinity of doped Ca2+ ions. Both Nd3+ crystal-field levels could be described using calculated parameters for NdMnO3. Also, while oxygen stoichiometry and coherent Jahn–Teller distortions seem not to be affected by Ca doping, increased absorption bandwidths characterize the doped crystals. 相似文献
156.
Ji-Jing Xu Hai-Feng Zou Gui-Mei Gao Shu-Cai Gan 《Journal of magnetism and magnetic materials》2009,321(19):3231-3235
Z-type ferrites doped with La3+, Ba3−xLaxCo2Fe24O41 (x=0.00-0.30), were prepared by sol-gel method. The effect of the substitution La3+ rare-earth ions for Ba2+ ions on the microstructure, complex permeability, permittivity and microwave absorption of the samples was investigated. The results show that the major phase of the ferrites changed to Z-phase when sintering temperature was 1250 °C for 5 h. With the increase of the substitution ratio of La3+ ions from 0.0 to 0.3, the lattice parameters a and c increased gradually, which resulted in the change of the particle shape and size. The data of magnetism showed that the addition of La3+ ions make the ferrite a better soft magnetic material due to increase of magnetization (σs) and decrease of coercivity (Hc). The La3+ ions doped in the ferrite not only improved complex permeability and complex permittivity, but also microwave absorbency. 相似文献
157.
稀土掺杂铕(Ⅲ)二苯甲酰甲烷邻菲咯啉三元配合物的合成和荧光性质 总被引:5,自引:1,他引:4
合成了 3个系列稀土掺杂铕二苯甲酰甲烷 (Hdbm)邻菲咯啉 (phen)三元配合物 Eux RE1 -x(dbm) 3 phen(RE=La,Y,Gd;x=0 .0 0、0 .1 0、0 .30、0 .5 0、0 .70、0 .80、0 .90、1 .0 0 ) ,通过元素分析、摩尔电导率、红外光谱、X射线粉末衍射对配合物进行了表征。对各配合物系列进行荧光光谱研究 ,发现 L a3 、Y3 和 Gd3 对Eu3 离子均有荧光增敏作用 ,其荧光增敏顺序为 L a3 >Y3 >Gd3 。 相似文献
158.
采用第一性原理方法研究了Ni_3Al_(1-x)V_x(x=0-0.4)的力学性质,发现当V含量为0.1时,Ni_3Al_(1-x)V_x的块体模量、剪切模量、杨氏模量和硬度都出现极大值,因此V掺杂对于Ni_3Al力学性能的提升具有重要作用.另外,还研究了不同压强下Ni_3Al_(0.9)V_(0.1)的吉布斯自由能、焓、熵、热容等热力学性质随温度的变化关系,结果表明:在高温高压条件下,Ni_3Al_(0.9)V_(0.1)的吉布斯自由能、焓、熵、定压热容都出现明显变化.通过计算Ni_3Al_(0.9)V_(0.1)的体膨胀系数,发现压强对于Ni_3Al_(0.9)V_(0.1)的体膨胀效应具有明显的抑制作用. 相似文献
159.
S. Selladurai K. Muthukkumaran P. Kuppusami R. Divakar E. Mohandas V. S. Raghunathan 《Ionics》2007,13(2):87-92
Microstructural characterization of thin films of 5 mol% gadolinia-doped ceria films deposited by pulsed laser ablation in
the energy range 100–600 mJ/pulse has been investigated. As-deposited films were found to be nanocrystalline with preferred
orientation. X-ray diffraction (XRD) analysis revealed that the size of the nanocrystals of doped ceria does not vary significantly
with increasing laser energy, while transmission electron microscopy (TEM) study showed a uniform distribution of nanocrystals
of 8–10 nm for energies ≤200 mJ/pulse and nanocrystals embedded in a large crystalline matrix of doped ceria for energies
in the range 400–600 mJ/pulse. Though, the laser-ablated films were totally free from secondary phases, lattice imaging of
the large grained doped ceria showed growth-induced defects such as dislocations and ledges.
This artice was accidentally published twice. This is the second publication, please cite only the authoritative first one
which is available at . An additional erratum is available at .
An erratum to this article can be found at 相似文献
160.
Performance of radar absorbing materials by waveguide measurements for X- and Ku-band frequencies 总被引:1,自引:0,他引:1
Magali Silveira Pinho Maria Luisa GregoriRegina Célia Reis Nunes Bluma Guenther Soares 《European Polymer Journal》2002,38(11):2321-2327
In this work, samples consisting of an elastomeric matrix containing different kinds of active materials in particulate form were prepared for reflectivity measurements. The materials individually used in weight contents of 80% in polychloroprene matrix were: carbonyl-iron (CI) and doped ferrite powders. The microwave reflectivity levels were determined from the magnetic and dielectric properties of the elastomeric composites obtained from scattering data, by fitting the samples in a waveguide, for measurements in the frequency range from 8 to 16 GHz. Better microwave absorption for X-band was obtained for CI while doped ferrite absorbed at higher frequencies (Ku-band). 相似文献