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刘晓峻, Z. Y. Pan, *, †, X.J. Lin, ‡, S. Y. Zhang, G. J. Shen, †, L.G, Zhang, Z. H. Lu, and J. Z. Liu†
J. Phys. Chem. B 1997, 101, 9703-9709,-0001,():
-1年11月30日
Two kinds of cadmium sulfide (CdS) particulate films have been generated in situ by exposing stearic acid (SA) Langmuir monolayer at the air-aqueous CdCl2 interface to hydrogen sulficde(H2S) gas: particulate films composed of oriented rodlike nanocrystals (A-type particulate films), and those of dotlike nanocrystals which formed a stripelike domain with straight edges aligned with 6-fold symmetry(B-type particulate fims). The SA-coated CdS particulated films were transferred to a solid substrate and examined by transmission electron microscopy (TEM) and photoacoustic spectroscopy (PAS). The dark field image and the transmission particulte fims in detail. The PAS of the CdS particulate fims coposed of the oriented rodlike nanocrystals shows a new peak at 417.5nm. This peak implies some new physical phenomena corresponding to the oredred alignmert of the semiconductor nanocrystals. which exists in the ordered nanosystems. The novel synthesis method described here leads to the fabricaiton of the highly oriented semiconductor quantum wires and provides a new method to investigate the structure of the Langmuir monolayer at the air-water interface.
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刘晓峻, Y. Cheng, J. Y. Xu, and X. J. Liu*
PHYSICAL REVIEW B 77, 045134 (2008) ,-0001,():
-1年11月30日
We present theoretically a type of one-dimensional _1D_ structured ultrasonic metamaterial that exhibits a forbidden band where both the effective dynamic density and bulk modulus are simultaneously negative. The material consists of a 1D array of repeated unit cells with shunted Helmholtz resonators. The transmission coefficient, wave vector, negative dynamic density, and modulus are determined by means of the acoustic transmission line method (ATLM). The double negativity in the effective dynamic density and bulk modulus is an acoustic counterpart of negative permittivity and permeability in the electromagnetic metamaterials. The double negative band is ascribed to the localresonance. In order to confirm the ATLM results, we further calculate the field intensity, phase distribution, and transmission coefficient using the finite element method. In addition, the influences of some essential geometric acoustic parameters on the transmission properties, such as periodic constant L, are also discussed.
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【期刊论文】The second-harmonic generation of a conical sound source
刘晓峻, Desheng Ding, Xiaojun Liu
,-0001,():
-1年11月30日
The second-harmonic sound beam nonlinearly generated by a conical source is analytically described It is shown that the radial second-hamonic beam is distributed as the Bessel function and independent of the porpagation distance. Anoher important feature is that the beamwidth of the second-harmonic component is just equal to 1/2 time that of the fundamental, not 1/√2 times in the general cases. A potential application of this beam in the acoustic noninearity parameter B/A imaging or measurement is also discussed.
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刘晓峻, X.J. Liu*, Q.J. Huang, S.Y. Zhang, A. H. Luo. C.X. Zhao
Journal of Physics and Chemisry of Solids 65(2004)1247-1251,-0001,():
-1年11月30日
The themal diffusivity has been ivestigatedin double perovskite Sr2MMoO6 (M=Fe, Mn and Co) by means of the mirage effect. We have found that the thermal diffusivity of metallic Sr2FeMoO6 is 0.39 cm2/s, wihich is larger than that (0.33cm2/s) of insulating Sr2MnMoO6 and Sr2CoMoO6. We further investigate the substitution effects of the La3+ions for the Sr2+ions in Sr2FeMoO6 and Sr2MnMoO6, and have found that the thermal diffusivities of both samples significantly increase with the La cncentration. Such an enhancement of the thermal diffusivities has been a scribed ot occupation of the extra itinerant electrons on te conducion Mo4d band.
A., Oxides, D., Transport properties, D., Phase transitions
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【期刊论文】A tunable acoustic filter made by periodical structured materials
刘晓峻, Jingshi Wang, Xiaodong Xu, Xiaojun Liu, , a and Gangcan Xu
APPLIED PHYSICS LETTERS 94, 181908 (2009),-0001,():
-1年11月30日
Three kinds of the periodical structures are designed as low-pass, high-pass, and band-pass filters for elastic wave. The theoretical simulations have proved that the periodical surface slots can act as a ow-pass filter for elastic wave. With increasing depth of the surface periodical structure in the sample,he cutoff frequency of the low-pass filter is decreased. Unlike the surface periodical structure, the eriodical subsurface structure can work as a high-pass filter for elastic wave. The cutoff frequency of the igh-pass filter is suppressed by the increase of the subsurface structure thickness. When the two eriodical structures are combined together, the band-pass filter is obtained, in which the pass band is etermined by the cutoff frequencies of the low-pass and high-pass filters. © 2009 American Institute of Physics. (DOI: 10.1063/1.3131043)
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