科研论文

返回至主页
  • Interface optical phonons in k-component fibonacci dielectric multilayers

    • 摘要:

      We present the studies of the interface optical phonons in k-component Fibonacci (KCF) dielectric multilyaers, in which k different incommensurate intervals are arranged according to a substitution rule. In the dielectric continuum approximation, the dispersion relations and the frequency spectra are obtained by the transfer-matrix method. Free-boundary and periodic-boundary conditions are taken into account. With the free-boundary condition, the dispersion relations of the interface optical phonons in the KCF multilayers are demonstrated to possess two bands of dual structures. For the KCF multilayers with (Formula presented) each subband is a self-similar structure and contains (Formula presented) filial generations; for the KCF multilayers with (Formula presented) the sub-bands do not show self-similarity, but they still have the hierarchical characteristic (where k is the number of different incommensurate intervals). In the case of the periodic-boundary condition, the frequency span of interface optical phonons in the KCF multilayers is singularly continuous and the frequency spectra are analyzed by a multifractal concept. A dimensional spectrum of singularities associated with the frequency spectrum, (Formula presented) demonstrates that in the KCF multilayers the interface optical phonons distribution presents a genuine multifractality. It is also shown that by increasing the number of different incommensurate intervals in KCF multilayers, the fractal dimension of the corresponding support decreases. © 1999 The American Physical Society.

    • 作者:

      Peng R. W.;Jin G. J.;Wang Mu;Hu A.;Jiang S. S.;Feng D.

    • 刊名:

      Physical Review B Condensed Matter and Materials Physics

    • 在线出版时间:

      1999

  • Effects of processing on the characteristics of SrBi2Ta2O9 films prepared by metalorganic decomposition

    • 摘要:

      SrBi2Ta2O9(SBT) films were prepared by metalorganic decomposition technique. The films were obtained by spin-on pyrolysis of the precursor solutions on various substrates and then annealed at 550-850°C in dry oxygen, wet oxygen, or Ar. Effects of precursor solution concentration, anneal temperature, anneal atmosphere, substrate and Ar ion sputtering on the microstructure, morphology and electrical properties were investigated by means of x-ray diffraction, scanning electron microscope, atomic force microscope, x-ray photoelectron spectroscopy, and electrical measurements. The results indicated the grain size, and the remnant polarization (Pr) increased with increasing the anneal temperature up to 800°C and the significant hysteresis loop could be obtained only after anneal above 700°C. At 850°C, the pyrochlore phase and other secondary phases were observed along with the SBT phase, leading to the decreasing Pr and dielectric constant. In addition, the development of crystalline phase and electrical properties were affected by anneal atmosphere. When annealed in Ar at 750°C, the layered SBT structure was destroyed with evident Bi loss. As though the original structure could be restored basically by subsequent adequate O2 anneal, the electrical properties were deteriorated seriously due to the shorted capacitor. Wet oxygen anneal evidently deformed the morphology and the hysteresis loop. This was attributed to the effect of possible produced slight H2 due to the reaction between H2O and residual carbonaceous in films under Pt catalyst. Substrates also played an important role on film crystallinity. The films deposited on Si, SrTiO3, and crystal quartz at 750°C had a layered perovskite polycrystalline structure while the films on fused quartz exhibited poor crystalline nature even after 800°C anneal and films on NaCl showed (200)-predominant orientation of SBT phase with some pyrochlore. In addition, Ar ion sputtering might lead to the severe Bi and oxygen deficiency in the surface of the sputtered film. © 2000 American Institute of Physics.

    • 作者:

      Li Aidong;Wu Di;Ling Huiqin;Yu Tao;Wang Mu;Yin Xiaobo;Liu Zhiguo;Ming Naiben

    • 刊名:

      Journal of Applied Physics

    • 在线出版时间:

      2000

  • Characterization of the diffraction spectra of one-dimensional k-component Fibonacci structures

    • 摘要:

      We study in this paper the diffraction spectrum (Fourier transform) of a one-dimensional k-component Fibonacci structure (KCFS), which contains k different intervals and can be generated by a substitution rule. Theoretical and numerical calculations based on the geometrical models for atomic KCFS have been made. The structures with 1

    • 作者:

      Peng R. W.;Wang Mu;Hu An;Jiang S. S.;Jin G. J.;Feng Duan

    • 刊名:

      Physical Review B

    • 在线出版时间:

      1995

  • LiNbO 3 grating couplers fabricated by one excimer laser pulse through a diffractive optical element

    • 摘要:

      One excimer laser pulse through a silicon glass phase mask was used to directly generate periodic surface structures on top of a lithium niobate (LN) wafer. The surface corrugations have a period that is the same as that of the mask grating. Measurement of the grating coupler with a He-Ne laser beam coupling into the waveguide found three mode of incident lights transmitting into the waveguide.

    • 作者:

      Luo Gui peng;Wang Mu;Zhu Shi ning;Liu Zhi guo;Lu Yan qing;Chen Xiao yuan;Ge Chuan zhe;Ming Nai ben;Wu Hai ming;Lu Zhu hong

    • 刊名:

      Pacific Rim Conference on Lasers and Electro Optics CLEO Technical Digest

    • 在线出版时间:

      1997

  • Effects of substrate temperature on the growth of oriented LiNbO 3 thin films by pulsed laser deposition

    • 摘要:

      Oriented LiNbO 3 thin films have been prepared by pulsed laser deposition on fused silica substrates under a proper low electric field. The as-grown films were characterized by means of X-ray diffraction θ-2θ scans, X-ray photo-electron spectrometry and atomic force microscopy. Significant effects of the substrate temperature and magnitude of the applied electric field on the orientation of the films are revealed, demonstrating the preferred electric field of ∼7 V/cm and substrate temperature of 600°C. Drastic influence of the substrate temperature on the stoichiometry of the thin films is also shown. The as-prepared thin films show quite good surface quality. © 1998 Elsevier Science B.V.

    • 作者:

      Wu Z. C.;Hu W. S.;Liu J. M.;Wang M.;Liu Z. G.

    • 刊名:

      Materials Letters

    • 在线出版时间:

      1998

  • One-dimensional, self-organized Si dots grown by pulsed laser melting of a-Si:H films

    • 摘要:

      We report a new method for one-dimensional, self-organized, nanometer-sized crystalline silicon (nc-Si) dots growth through pulsed laser-induced melting followed by regrowth of a-Si:H films. A transient thermal grid was generated by a high energy KrF excimer laser through a phase shifting mask grating directly on the samples, leading to local phase transitions. The hemispherically shaped nc-Si dots with sizes of ∼200 nm in diameter and ∼20 nm in height were grown and self-organized along the lines of the grating. The microstructures and crystallinity of the nc-Si dots were determined using atomic force microscope images and cross-section transmission electron microscope photographs; and the growth mechanism of self-organized nc-Si dots is also discussed. © 1998 Elsevier Science B.V. All rights reserved.

    • 作者:

      Chen Kunji;Luo Guipeng;Wang Mingxiang;Gao Xiang;Xu Jun;Wang Mu;Huang Xinfan;Ming Naiben

    • 刊名:

      Journal of Non Crystalline Solids

    • 在线出版时间:

      1998

  • Growth-induced magnetic anisotropy behavior in Ni thin films

    • 摘要:

      The magnetic anisotropy of Ni thin films fabricated under different growth conditions have been studied by the ferromagnetic resonance (FMR) method. The FMR data have been fitted theoretically. The results show that the anisotropy is an orthorhombic anisotropy, and there exists an optimal rotary speed of the sample for a fixed deposition rate. Near the optimal speed, the anisotropy field along the in-plane easy axis exhibits a maximum, while the anisotropy field perpendicular to the film plane exhibits a minimum. The origin of orthorhombic anisotropy has been discussed. © 1998 Elsevier Science B.V. All rights reserved.

    • 作者:

      Kang S. S.;Liu X. Y.;Xiang X. H.;Jin G. J.;Du J. H.;Lu M.;Wang Mu;Sui Y. X.;Hu A.;Jiang S. S.;Feng D.;Feng J. W.;Xia H.

    • 刊名:

      Journal of Magnetism and Magnetic Materials

    • 在线出版时间:

      1998

  • Intrinsic instability of the concentration field in diffusion-limited growth and its effect on crystallization

    • 摘要:

      The dynamic behavior of the concentration field in crystallization is investigated by considering the coupling of the bulk concentration field and interfacial kinetics. It is shown that the concentration field may become unstable for perturbations with certain wavelength. When instability occurs, the physical environment in front of the growing interface will fluctuate and the interfacial growth mode will be affected accordingly. We suggest that our analysis can be used to interpret some spatial-temporal instabilities observed in crystallization. © 1999 The American Physical Society.

    • 作者:

      Wang Mu;Yin Xiao-Bo;Peng Ru-Wen;Ming Nai-Ben;Vekilov Peter G.

    • 刊名:

      Physical Review E Statistical Physics Plasmas Fluids and Related Interdisciplinary Topics

    • 在线出版时间:

      1999

  • Giant magnetoresistance and domain observation of Co 35 (SiO 2 ) 65 nano-granular film

    • 摘要:

      A series of Co 35 (SiO 2 ) 65 (volume fraction) nano-granular films with different annealing temperature (T A ) were fabricated using ion-beam sputtering technique. A giant magnetoresistance of about 4% at room temperature was observed. The transmission electronic microscopy (TEM) observation shows clearly isolated nano-scale cobalt particles embedded in the SiO 2 matrix. A magnetic force microscopy (MFM) was used to image the topography and magnetic microstructures of Co 35 (SiO 2 ) 65 nano-granular film. The domains were resolved clearly on MFM micrographs with much larger size (about 10-20 nm) than that of cobalt particles (about 1-2 nm) in the annealed samples, which demonstrated that there may be interparticle correlation among many of the isolated single-domain cobalt particles.

    • 作者:

      Xu Q. Y.;Chen H.;Sang H.;Yin X. B.;Ni G.;Lu J.;Wang M.;Du Y. W.

    • 刊名:

      Journal of Magnetism and Magnetic Materials

    • 在线出版时间:

      1999

  • Electronic transport in k-component fibonacci quantum waveguides

    • 摘要:

      We present a study of electronic behaviours in the k-component Fibonacci (KCF) quantum waveguides, in which k different incommensurate intervals are arranged according to a substitution rule. On the basis of the transfer matrix method, the quantum transmission properties of the KCF stub structures are obtained. It is shown that the transmission coefficient depends on the wavevector of the electron and the number of different incommensurate intervals k. For the KCF waveguides with the same k, on increasing the number of stubs, the minima in transmission extend gradually into the band gap over which the transmission is blocked. Meanwhile more transmission peaks appear. For finite KCF stub structures, on increasing the number of different incommensurate intervals k, the total transmission over the spectral region of interest decreases gradually and the width of the electronic band gap is enlarged. Moreover, when the value of k is large enough, the transmission is basically shut off, except at a few energies where resonant tunnelling takes place. These properties make it possible to use this kind of KCF waveguide as a switching device for digital applications. On the other hand, the charge-density distributions in these structures are singularly continuous. We propose that they can be analysed using a multifractal concept. A dimensional spectrum of singularities associated with the charge density, f(α), demonstrates that the electronic transport in the KCF waveguide presents scaling properties; hence the charge-density distribution shows a genuine multifractality.

    • 作者:

      Peng R. W.;Jin G. J.;Wang Mu;Hu A.;Jiang S. S.;Feng D.

    • 刊名:

      Journal of Physics Condensed Matter

    • 在线出版时间:

      2000

共13页 转到