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91.
简要回顾了20世纪20年代以来我国现代磁学研究的历史。20世纪80年代初期正值我国改革开放浪潮之时,科技人员纷纷走上科技成果产业化道路。建立于1985年的中国科学院三环公司就是一个成功的代表,同时好也是我国现代磁学研究结出的一颗硕果。 相似文献
92.
XIE Bai-Song DU Shu-Cheng 《理论物理通讯》2006,46(10)
Numerical axisymmetric soliton and oscillating wave solutions for the Flierl-Petviashvili equation in plasmas are presented. Solution branch paradigm and examples are given. Some implications of results to ion drift wave as well as force-free field of magnetic equilibrium are briefly discussed. 相似文献
93.
The dynamic Young modulus (E) of magnetic Nd2Fe14B+αFe nanocomposites is investigated with mechanical spectroscopy techniques (vibrating reed configuration, f≈1.5 kHz <10−6). Reduced values of E are obtained (88–152 GPa) as compared with that predicted by the rule of mixtures for the composite (164 GPa). Three contributions to this reduction are briefly discussed: a large volume fraction of the specimen with grain boundary like structure; internal pores, resulting from the high cooling rate during processing (106 K/min) and magneto-mechanical effects. Even when porosity is identified as the principal cause of modulus reduction, magnetic effects are also detected. 相似文献
94.
M. A. Macrì C. Del Gratta L. Di Donato S. Di Luzio G. L. Romani S. Della Penna A. Pasquarelli 《Il Nuovo Cimento D》1994,16(5):425-432
Summary A preliminary study is here reported on a new potential marker for biomagnetic measurements. The marker consists of superparamagnetic
polymer microspheres which were detected in the presence of external steady magnetic fields by means of an r.f.-SQUID magnetometer.
The particles were prepared in samples differing in the concentration value and immersed in a homogeneous magnetic field of
variable intensity. A simple model was taken into account for the distribution of the microspheres in the samples, so that
the theoretical values were compared to the marker field values measured by the biomagnetic sensor. The overall sensitivity
of the experimental apparatus and the minimum concentration value of the marker were then estimated. 相似文献
95.
K. Prokeš 《Czechoslovak Journal of Physics》2002,52(2):253-258
Many materials exhibit various magnetic phenomena as a function of magnetic field, temperature and/or pressure. Usually, bulk magnetic measurements provide first information on the magnetic state of the material by measuring their response on the applied magnetic field. However, it is necessary to investigate materials also on a microscopic scale. This is often done by means of neutron scattering. In this contribution we discuss basic ideas of this method and we report on few experimental results obtained with a split-pair coil 14.5 T superconducting magnet which can be combined with dilution stick offering temperatures as low as 30 mK and/or with a small clamped-type pressure cell which offers pressure up to 1.0 GPa. 相似文献
96.
In this paper, experimental results of the investigation of the periodic structure on thermoelectric semiconductor Cu2Se are presented. Periodic structures were formed on surfaces of semiconductors due to multi-beam interaction of Q-switched Nd:YAG laser, which was operated in the lowest order of Gaussian mode and pulse duration 7 ns. Surface temperature evolution and transient reflectivity are studied during laser treatment. Creation of Cu islands in the maximal intensity of interference pattern was found. 相似文献
97.
E. V. Voronina E. P. Yelsukov A. V. Korolyov A. E. Yelsukova 《Hyperfine Interactions》2006,168(1-3):1079-1083
The experimental data from Mössbauer spectroscopy and magnetic measurements are presented as functions of the temperature and external magnetic field for a B2-type ordered Fe 66 Al 34 alloy. 相似文献
98.
B. Sahoo W. Keune E. Schuster W. Sturhahn T. S. Toellner E. E. Alp 《Hyperfine Interactions》2006,168(1-3):1185-1190
Amorphous (a-) Fe x Mg1?x alloys are interesting materials for the investigation of non-Debye-like low-energy vibrational excitations. We have prepared a-Fe x Mg1?x alloy thin films (0.3 ≤ × ≤0.7) by vapour quenching. The amorphous state was confirmed by conversion electron Mössbauer spectroscopy between 4.2–300 K, and the x- and temperature-dependence of the isomer shift and hyperfine magnetic field was measured. For x= 0.6 and 0.7, magnetic ordering occurs below ~150 K. The atomic vibrational density of states, g(E), was determined by nuclear resonant inelastic scattering, providing clear evidence for the non-Debye-like low-energy vibrational excitations. 相似文献
99.
Alignment of photon-induced L3 vacancies is studied in rare earth and highZ elements at energies of experimental interest, near thresholds to 60 keV, under nonrelativistic dipole approximation. Numerical
calculations of the matrix element are undertaken to produce theoretical data for comparison with the experimental findings.
The A2 values being s>0.1 at photoelectron energies <20 keV are certainly higher than 5–8% uncertainties quoted in experimental
results. Present findings are from a very basic model, hydrogen-like and can further be treated as reference to observe the
impact of screening, relativistic, multipole and retardation corrections to the model 相似文献
100.
Michael Grätzel 《Journal of Sol-Gel Science and Technology》1994,2(1-3):673-677
Transparent nanocrystalline films of oxide semiconductors such as TiO2 and Fe2O3 have been prepared on a conducting glass support employing a sol-gel procedure. The films are composed of nanometer-sized particles sintered together to allow for percolative charge carrier transport. The internal surface of these films is very high, roughness factors of the order of 1000 being readily obtained. Electric polarization was applied for forward and reverse biasing of the films and the resulting optical changes have been analyzed to derive their flat band potential. Band gap excitation of such nanocrystalline semiconductors produces electron-hole pairs which migrate through the film to be collected as electric current. Steady state photolysis and time resolved laser techniques have been applied to scrutinize the mechanism of light induced charge separation within the nanostructure. When derivatized with a suitable chromophore, TiO2 films give extraordinary efficiencies for the conversion of incident photons into electric current, exceeding 90% for certain transition metal complexes within the wavelength range of their absorption band. The underlying physical principles of these astonishing findings will be discussed. Exploiting this discovery, we have developed a new type of photovoltaic device whose overall light to electric energy conversion yield is 10% under simulated AM 1.5 solar radiation. 相似文献