Papers by Keyword: Polycrystalline

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Authors: Yekinni K. Sanusi, Adegoke Ojeniyi, Nordin Norani
Abstract: The photovoltaic (PV) system output performance is not independent as it varies over extended periods as well as it depends on the varying atmospheric conditions. In this work, the effect of ambient temperature and relative humidity on the efficiency performance of the polycrystalline PV system was investigated and analyzed in a tropical region. This was done by using a measurement system consists of sensors for measuring both electrical of the system and the atmospheric parameters concurrently at interval of time for a period of a year at the back of Pure and Applied Physics Department, Ladoke Akintola University of Technology Ogbomoso, Nigeria. From the measurements obtained, it was deduced that the performance efficiency of the system varied with the variation in the magnitude of the atmospheric parameters. The maximum daily value of efficiency obtained was 55% between the ambient temperature and relative humidity of 33oC to 34oC and 50% to 55% respectively. This can serve as a baseline to the PV designers and users for adequate installation of the system in the study area and other areas that have similar solar characteristics.Key words: Photovoltaic, polycrystalline, solar cell, semiconductor, efficiency.Corresponding Author:
Authors: G.H. Tariq, Muhammad Anis-ur-Rehman
Abstract: Polycrystalline thin films of Cadmium Sulfide (CdS) have been extensively studied for application as a window layer in CdTe/CdS and CIGS/CdS thin film solar cells. Higher efficiency of solar cells is possible by a better conductivity of a window layer, which can be achieved by doping these films with suitable elements. CdS thin films were deposited on properly cleaned glass substrate by thermal evaporation technique under vacuum2×10-5mbar. Films were structurally characterized by using X-ray diffraction. The X-ray diffraction spectra showed that the thin films were polycrystalline in nature. Aluminum was doped chemically in as deposited and annealed thin films by immersing films in AlNO33.9H2O solutions respectively. Comparison between the effects of different doping ratios on the structural and optical properties of the films was investigated. Higher doping ratios have improved the electrical properties by decreasing the resistivity of the films and slightly changed the bandgap energy Eg. The grain size, strain, and dislocation density were calculated for as-deposited and annealed films.
Authors: G. Farhi, R. Cherfi, M. Aoucher, K. Zellama
Authors: M. Zaghdoudi, M.M. Abdelkrim, M. Fathallah, T. Mohammed-Brahim, F. Le Bihan
Abstract: The optical and electrical properties of undoped and low doped polycrystalline silicon films deposited by LPCVD technique are analysed. Photothermal deflexion spectroscopy, and electrical conductivity in the temperature range 50- 475 K are used. The effect of low phosphorus doping on the density of defects, electrical parameters and hopping conduction are examined and interpreted in conjunction with the passivation of defects by the introduction of phosphorus atoms. The density of states at the Fermi level is also calculated.
Authors: Juan Luo, Guo Zheng Kang, Otto T. Bruhns, Chuan Zeng Zhang
Abstract: In the framework of crystal plasticity, a new cyclic polycrystalline viscoplastic model is constructed to describe the uniaxial ratchetting of a body centered cubic (BCC) metal. At the intra-granular scale, a combined kinematic hardening rule similar to the Ohno-Abdel-Karim model is employed to address the ratchetting within each single crystal grain; and two sets of slip systems with different resistances to dislocation slip, i.e., primary and secondary ones, are considered to capture the physical nature of dislocation slips in a body centered cubic (BCC) metal. At the inter-granular scale, an explicit transition rule is adopted to extend the single crystal approach into a polycrystalline version. It is shown that the proposed model describes the uniaxial ratchetting of annealed 42CrMo steel, a body centered cubic (BCC) metal, reasonably. Also, it is seen that the crystal orientation influences significantly the ratchetting of body-centered cubic (BCC) single crystals.
Authors: Georges Lemos, Márcio C. Fredel, Florian Pyczak, Ulrich Tetzlaff
Abstract: Ni-based superalloys, in both single and polycrystalline varieties, are extensively used in high pressure turbine blades. But contrary to single crystal variants, the polycrystalline forms present easier manufacturing and offer higher potential for improvement in metal matrix composites (MMCs). To benefit from this opportunity, an Inconel X-750 superalloy reinforced with TiC particles is proposed, having a polycrystalline microstructure and the possibility for weight reduction in turbine elements application. The metallic powder with an addition of 15 vol.% of 3.7 μmd TiC particles was prepared through low energy mixing, uniaxial pressing and sintering, followed by a triple heat treatment. The microstructure was analyzed with SEM and XRD techniques. Compressive creep tests were performed at 800 °C with 200 MPa, on both original and reinforced alloys. The study shows how the inclusion of a highly compatible particle reinforcement does not only improves the creep resistance, but also reduces the material weight, thus having potential to promote further reduction in the creep rate on turbine blades submitted to centripetal forces.
Authors: Lei Ma, Wei Guang Yang, Ya Li Wang, Gong Long Liu, Ke Tang, Lin Jun Wang, Wei Min Shi
Abstract: Polycrystalline α-HgI2 films have been grown through combining vertical deposition method with hot wall vapor phase deposition (HWPVD) method. The influence of the α-HgI2 seed layers on the structural and electrical properties of the polycrystalline α-HgI2 films was investigated. It is found that the α-HgI2 seed layers play an important role in reducing the grain sizes, increasing the density improving the crystallographic orientation and electrical properties of the polycrystalline α-HgI2 films.
Authors: Song Lin Ding, John P.T. Mo, Milan Brandt, Richard Webb
Abstract: The poor electric conductivity of polycrystalline diamond (PCD) makes it difficult to machine with the conventional EDM process. Inappropriate selection of parameters of the power generator and the servo system leads to unstable working condition and low material removal rate. This paper introduces a method to find optimal parameters in the Electrical Discharge Grinding (EDG) of PCD materials with Taguchi method. The theory and detailed procedures are presented, experimental results are analyzed. The optimized configuration was validated through confirmation tests.
Authors: Subrat K. Barik, Sudipta K. Bera
Abstract: The polycrystalline sample of (BiLi) 1/2 (FeV) 1/2O3 was prepared by a high-temperature solid-state reaction technique. A preliminary X-ray structural analysis exhibited the formation of single-phase compound with an orthorhombic structure. Detailed studies of electrical properties of the compound, investigated in a wide frequency range (1kHz-1MHz) at different temperatures by complex impedance spectroscopy (CIS) technique, showed that these properties of the material are strongly dependent on frequency and temperature. Ac conductivity is found to obey the Johnscher’s law. The M-H curve shows the presence of ferromagnetism in the studied compound.
Authors: F.V. Farmakis, D.M. Tsamados, J. Brini, G. Kamarinos, C.A. Dimitriadis
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