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Polycrystalline Nature (polycrystalline + nature)

Distribution by Scientific Domains

Polymers and Materials Science	50%
Physics and Astronomy	50%

Selected Abstracts

Physical properties of Dy and La doped SnO2 thin films prepared by a cost effective vapour deposition technique

CRYSTAL RESEARCH AND TECHNOLOGY, Issue 10 2006
J. Joseph
Abstract Stannous oxide (SnO2) thin film is one of the most widely used n-type transparent semi-conductor films in electronics, electro-optics and solar energy conversion. By achieving controlled non-stoichiometry, we can get good transparency and high electrical conductivity simultaneously in SnO2 thin films. Dy and La doped SnO2 thin films have been prepared by a cost effective vapour deposition technique. The structural, photo-electronic, optical and electrical properties of the doped and undoped films were studied. The results of X-ray Diffraction studies reveals the polycrystalline nature of the films with preferential orientation along the (101), (211) and (301) planes and their average grain size variation for different deposition temperature. Photoconductivity and Photovoltaic studies of the films were also performed. The optical properties of these films were studied by measuring their optical transmission as a function of wavelength. The optical transmission is found to be increased on Dy doping and decreased on La doping. The band gap, refractive index and thickness of the films were calculated from U-V transmittance and Absorption graphs. The optical band gap of undoped film is found to be 4.08 eV, but on doping it shifts to lower energies and then increases on increasing the concentration of both dopants. Its electrical parameters such as sheet resistance, resistivity, mobility, Hall coefficient, and carrier concentration were determined by Four Probe, Van der Pauw and Hall Probe method. On doping with Dy, carrier conversion takes place from n-type to p-type and p-conductivity dominates. On La doping no carrier conversion takes place but resistivity decreases. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Novel Synthesis of Pt6Si5 Nanowires and Pt6Si5,Si Nanowire Heterojunctions by Using Polycrystalline Pt Nanowires as Templates ,

ADVANCED MATERIALS, Issue 7-8 2003
J. Luo
Pt6Si5 nanowires and Pt6Si5,Si nanowire heterojunctions (see Figure) have been synthesized by electrodeposition using polycrystalline Pt nanowires as templates. In the synthesis, the polycrystalline nature of the Pt nanowires played an important role. A dependence between the diameters of the products and the Pt nanowires was detected. These junctions would find applications in future nano-electronics. [source]

Preferred Orientation of Bi4Ti3O12 Thick Film

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2007
Yoshiaki Kinemuchi
The preferred orientation of thick films prepared by paste printing is rarely observed because of their bulky polycrystalline nature. We found that a Bi4Ti3O12 thick film with a thickness of ca. 20 ,m showed c -axis-preferred orientation. Initially, the texture of the screen-printed film was found to have a random orientation, which was attributed to the equiaxed particle shape of the raw powder synthesized by the co-precipitation method. During subsequent heating, c -axis orientation emerged in which the degree of orientation was proportional to the film density. Analysis of the orientation distribution revealed that the progress of texturing was attributed to the film deformation, indicating that anisotropic shrinkage and morphological changes in particles during heating influenced the preferred orientation. [source]

Preparation and characterization of pulse electrodeposited GaAs films

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 5 2006
K. R. Murali
Abstract GaAs is a III,V compound possessing high mobility and a direct band gap of 1.43 eV, making it a very suitable candidate for photovoltaic applications. Thin GaAs films were prepared by plating an aqueous solution containing GaCl3 and As2O3 at a pH of 2 and at room temperature. The current density was kept at 50 mA cm,2 and the duty cycle was varied in the range 10,50%. The films were deposited on titanium, nickel and tin oxide coated glass substrates. Films exhibited polycrystalline nature with peaks corresponding to single-phase GaAs. Optical absorption measurements indicated a direct band gap of 1.40 eV. Atomic force microscope measurements indicated uniform coverage with large crystallites for the films deposited at higher duty cycles. Photoelectrochemical cells were made using the films as photoelectrodes and graphite as counter electrode in 1 M polysulphide electrolyte. At 60 mW cm,2 illumination, an open-circuit voltage of 0.5 V and a short-circuit current density of 5.0 mA cm,2 were observed for the films deposited at a duty cycle of 50%. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]