We present the growth of textured TiO₂ thin films on muscovite mica using pulsed laser deposition. Atomic force microscopy, scanning electron microscopy, X-ray photoemission spectroscopy, and transmission electron microscopy were used to characterize the TiO₂ films. Quasi-periodic wavy and comb-like buckles were observed. Below a critical thickness of about 25 nm, TiO₂ films were relatively smooth, and buckles began to form when the nominal thickness of TiO₂ films was larger than 25 nm. Co-existence of wavy and comb-like quasi-periodic buckles was observed when the nominal thickness of TiO₂ films was larger than 100 nm. The film stress is compressive due to the competition of the tensile stress from the lattice mismatch and the growth stress. The buckle delamination occurred when the compressive stress overcome the adhesion strength of the TiO₂ films on mica. A value of adhesion strength around 0.9 MPa for TiO₂ on mica is obtained. The symmetric domains of buckles are assigned to the anisotropic lattice mismatch for TiO₂ on mica.

Fengzhou Zhao;Bing Wang;Xuefeng Cui;Nan Pan;Haiqian Wang;建国 侯

Thin Solid Films

2005-10-1

We propose a new class of Graphite Intercalation Compounds (GICs) containing C₆₀ and alkali metals. The compound C₃₂K₄C₆₀ is predicted and attempts to synthesize it using a C₈K precursor and benzene-dissolved C₆₀ are reported. C₈K samples exposed to C₆₀ and benzene display a reproducible resistive transition at 19.5K indicative of superconductivity. C₈K samples exposed to benzene alone show no transition for T > 4.2K. Possible origins of the superconductivity are discussed.

M. S. Fuhrer;建国 侯;X. D. Xiang;A. Zettl

Solid State Communications

1994-5

Scanning tunneling microscopy (STM) can provide us the special means to characterize the locally physical and chemical properties of individual molecules, and even help us to manipulate the individual molecules for constructing new molecule-scale devices. Here we have adopted two new types of STM techniques to characterize the encapsulated metal atom inside a fullerene cage, and to construct a molecule-device with strong Kondo effect, respectively. The spatially dI/dV mapping spectra were used to unveil the energy-resolved metal-cage hybrid states of individual Dy@C₈₂ molecule, and the important information about the spatial position of Dy atom inside the cage and the Dy-cage interaction was revealed. The high voltage pulse by STM tip was controlled to induce the dehydrogenation of Co phthalocyanine molecule and change its adsorption configuration on Au(111) surface, so as to recover Kondo effect that disappears in the case of intact adsorbed molecule.

Bin Li;建国 侯

Chinese Journal of Chemical Physics

2007-8-1

The charge transfer across the metal-C₆₀ interface may provide an opportunity to form novel fullerene interface compounds in some kinds of low dimensional structures. Nanoscale materials and composite structures that have very high ratios of surface area to volume are certainly good candidates for finding new fullerene-metal interface compounds. Different numbers of electrons could be transferred from the metal to C₆₀ by manipulating the microstructure of the Al-C₆₀ and Cu-C₆₀ multilayers. The possibility of making metal-C₆₀ composites were explored and the relation between the charge transfer and the microstructure were investigated.

建国 侯;Xiang Li;永庆 李;Haiqian Wang

Advanced Materials

1999

Metal/organism multilayer films are formed on amorphous carbon film from ligand-stabilized silver nanoparticles by electrophoretic technique. The polarization and inducement of electric field as well as irradiation time of synthesizing ligand-stabilized silver nanoparticles are key factors in the process of forming metal/organism multilayer films. The concentration of surfactant also has striking influence to the growth of multilayer films.

H. X. Li;M. Z. Lin;建国 侯

Journal of Materials Science Letters

2000

C₆₀ (111) films have been grown on Ni₃Co(111) single-crystalline substrate using hot-wall diffusion method. The XRD and SEM results show that, high-quality C₆₀(111) single-crystalline film with grain size of ∼1μm can be obtained at the substrate temperature of 150°C.

Jianlin Zeng;Yan Wang;Yongqing Li;建国 侯

Physica C: Superconductivity and its Applications

1997-8

High optical quality single crystal fibers of β-BaB2O4 (BBO), an important nonlinear optical material, were grown along the second-harmonic generation phase matching direction by the laser heated pedestal growth method. The effects of various growth parameters, especially growth rate, on growth stability and fiber quality were investigated. It was found that 0.25mm/min is the suitable growth rate which can reduces the harmful effects of growth anisotropy and constitutional supercooling on fiber quality.

建国 侯;Tang Dingyuan;Chen Chuangtian;Ye Linghua;Chen Jiqin;Ding Zuchang

Chinese Physics Letters

1990-12

The superconducting transition temperature, C, defines the point at which the free energies of the superconducting and normal states of a material become equal. Just above C, thermodynamic fluctuations produce small, transient regions of the superconducting state, giving rise to an anomalous increase in the normal-state conductivity known as paraconductivity. This situation is analogous to the fluctuating regions of correlated spins found near the Curie-Weiss transition in ferromagnets. Such fluctuations are of theoretical significance in that they provide a direct probe of critical phenomena in general, and a stringent test of scaling theories, which describe the approach to the critical point. Paraconductivity effects are strongly dependent on the dimensionality of the system, although for conventional superconductors, three-dimensional fluctuation conductivity has to our knowledge never been observed. Here we report the observation of pure, three-dimensional paraconductivity in single crystals of the recently discoveredsuperconductors Kand Rb In addition to probing the critical state near c, these measurements allow the indirect determination of the residual, normal-state resistivity.

X. D. Xiang;建国 侯;Vincent H. Crespi;A. Zettl;Marvin L. Cohen

Nature

1993

In this paper, we focus on a graphene heterojunction device: a Z-shaped graphene nanoribbon, which consists of two armchair leads and a zigzag junction. Based on the Landauer-Büttiker formula and the tight binding model, we found that the rectifying behavior can be achieved by applying an external gate voltage in the heterjunction region. We also found that the rectification effect is independent of junction width and length, it is an intrinsic property of the Z-junction graphene nanoribbon. This platform can be used to design and study functional graphene nanoscale devices.

Z. F. Wang;群祥 李;Q. W. Shi;Xiaoping Wang;建国 侯;Huaixiu Zheng;Jie Chen

Applied Physics Letters

2008

We present the preparation of C54 TiSi ₂ nanoislands on Si (1 1 1) with a method of the pulsed laser deposition of titanium oxide thin films. The TiO ₂ thin films with nominal thicknesses of 1 nm on Si (1 1 1) were annealed at 850 °C for about 4 h in situ. The X-ray diffraction patterns and the X-ray photoelectron spectra indicate that the nanoislands are in C54 TiSi ₂ phase. The characterization using a scanning tunneling microscope shows that the nanoislands with triangular, polygonal and rod-like shapes on Si (1 1 1) exhibit the Volmer-Weber growth mode. The sizes of the polygonal islands distribute in two separated ranges. For the small islands, they have a narrow lateral size distribution centered at 4 nm and a height range in 0.6-3.6 nm, while for the large islands, their lateral sizes are in the range of 12-40 nm and the heights in the range of 4-9 nm. The sizes of the well-shaped triangular islands are intermediate with the lateral sizes in range of 5-20 nm and the heights of 2-3.5 nm. The rod-like islands are about 50-200 nm in length, 5 nm in height and about 15-20 nm in width. The origination of the various shapes of the nanoislands is attributed to the symmetry of Si (1 1 1) substrate and the lattice mismatch between the C54 TiSi ₂ and the Si (1 1 1) surface.

Fengzhou Zhao;Xuefeng Cui;Bing Wang;建国 侯

Applied Surface Science

2006-12-30