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991.
The magnetic and dielectric properties of multiferroic Sr- substituted Zn2-Y hexagonal ferrites 下载免费PDF全文
The magnetic and dielectric properties of Sr-substituted Zn2-Y hexagonal ferrites (Ba2-x SrxZn2Fe12O22, 1.0 〈 x ≤ 1.5) are studied in this paper. Sr substitution will lead to the variation of cation occupation, which influences both the magnetic and electric properties. As Sr content x rises from 1.0 to 1.5, magnetic hysteresis loop gets wider gradually and the permeability drops rapidly due to the transformation from ferrimagnetic to antiferromagnetic phase. Moreover, permittivity rises with increasing Sr content. Under a certain external magnetic field, the phase transition of helical spin structure of Ba0.5Srl.5Zn2Fe12O22 at about 295 K seems to open a possibility for the room-temperature ferroelectricity induced by magnetic field. But its low resistivity prevents the observation of ferroelectric and magnetoelectric properties at room-temperature. 相似文献
992.
The target type flowmeter based on fiber Bragg gratings (FBGs) is experimentally studied. The relationship between the central wavelength shift of FBG and the flux is derived and the analytic expression is also given. Simulation and preliminary experiments have been carried out, and experimental validation of the water further proves the feasibility of the sensor. The experimental results verify the proposed sensor which can measure flux range from 200 to 1200 cm^3/s. And on this basis, the improvement program is raised. 相似文献
993.
Cheng CX Tian Y Shi YQ Tang RP Xi F 《Langmuir : the ACS journal of surfaces and colloids》2005,21(14):6576-6581
Fabrication of honeycomb patterned films from our synthesized amphiphilic dendronized block copolymer by "on-solid surface spreading" method and "on-water spreading" method was reported for the first time in this paper. The comparison of the two methods indicated honeycomb-patterned films with smaller size, and larger surface density of micropores can be fabricated by spreading on water but with lower regular arrangement. Furthermore, several influencing factors on the formation of the honeycomb structure and the different morphologies, such as the concentration of the copolymer solution and the relative humidity in the atmosphere and the substrates, were investigated. The results showed that comparably high relative humidity from 80% to 95% was needed, and the mica plate as a spreading substrate was suitable to form orderly porous films for such a copolymer. The best ordered pattern could be formed from the copolymer with concentration of 1.00 mg/mL at the relative humidity of 85% using a mica plate. Besides, strong periodicity, regularity, and a large, defect-free area were notable, which made this structure extremely interesting for applications for templated molecular objects formed via intramolecular metal or metal oxide synthesis. 相似文献
994.
Square and round single crystalline SnO platelets have been prepared in a solution-based chemical route aided with sonication at room temperature. 相似文献
995.
S.L. Xu Q.D. Zeng P. Wu Y.H. Qiao C. Wang C.L. Bai 《Applied Physics A: Materials Science & Processing》2003,76(2):209-212
The molecular assembly of three different trialkyloxy-substituted benzaldehydes on graphite has been studied using scanning
tunneling microscopy (STM). It is found that these benzaldehydes, which do not have intermolecular hydrogen bonding, could
form a lamella arrangement in which the headgroups are aligned side by side. The effect due to the alkyl chain length on the
lamella structure is also presented.
Received: 21 January 2002 / Accepted: 22 March 2002 / Published online: 10 September 2002
RID="*"
ID="*"Corresponding author. Fax: +86-10/6255-7908 相似文献
996.
Xiao-Qing Shen Zhong-Jun Li Hai-Bin Qiao Hong-Ying Wang 《Journal of Physics and Chemistry of Solids》2005,66(10):1755-1760
The crystalline structure of some compounds containing the 1,3,4-thiadiazole moiety, (1) 5-ethyl-2-amino-1,3,4- thiadiazole (EATZ), (2) 5-benzylsulfany-2-amino-1,3,4-thiadiazole (BSATZ) and (3) 2,5-bis-benzylsulfanyl-1,3,4-thiadiazole (BBSTZ) were determined. Both EATZ and BBSTZ show orthorhombic structures with space group Pbca and BSATZ a monoclinic system with space group C2/c. The lattice parameters: a=0.72280 (14), b=1.0811 (2), c=1.6210 (3) nm for 1, a=2.5282 (5), b=0.59083 (12), c=1.5390 (3) nm for 2 and a=0.87530 (18), b=1.0365 (2), c=3.6098 (7) nm for 3. To compare the intra- and intermolecular interactions in thiadiazole containing organic crystals, thermal analysis studies on each crystal is performed using DSC and TG in N2 atmosphere to describe the thermal behaviors. Based on the results, the changing regularity of melting point and decomposition temperature of these compounds is educed 相似文献
997.
[reaction: see text] A versatile synthesis of PI(3,4)P2, PI(4,5)P2, and PI(3,4,5)P3 is disclosed, starting from L-(-)-quebrachitol, a byproduct of latex production. The crystalline nature of most intermediates and the utilization of inexpensive protecting groups facilitate this synthetic route and its scale-up. 相似文献
998.
999.
1000.
Er3+ doped SrTiO3 ultrafine powders were prepared by solid state reaction in a molten NaCl flux. The structural properties were characterized by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. The Stokes emission spectra of Er3+ in SrTiO3:Er3+ ranging from green to near infrared region were investigated under 514.5 nm laser excitation. The green and redupconverted luminescence spectra of Er3+ were measured under excitation into the 4I9=2 level by 785 nm laser. The upconversion mechanisms were studied in detail through laser power dependence and Er3+ ion concentration dependence of upconverted emissions, and results show that excited state absorption and energy transfer process are the possible mechanisms for the upconversion. The upconversion properties indicate that SrTiO3:Er3+ may be used in upconversion phosphors. 相似文献