• Korean Journal of Computational Design and Engineering
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• v.2 no.2
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• pp.71-76
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• 1997

The deformations of polycrystalline materials are modelled by linking a constitutive equation for the crystallographic slip of a single crystal to the macroscopic behavior of the aggregate. In this study, anisotropic elasticity (lattice stretching) of a cubic crystal is incoporated into the anisotropic plasticity from crystallographic slip. The constitutive description for the aggregate, derived from a crystal plasticity theory, is used to formulate a Consistent Penalty Finite Element Method for the anisotropic elasto-viscoplastic deformation of polycrystalline materials. As an application, a plane-strain forging process is simulated and the effects of the initial textures on the deformation behavior of the workpiece are examined.

• Journal of the Korean Ceramic Society
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• v.35 no.9
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• pp.1002-1005
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• 1998

Bismuth titanate thin films were prepared on {{{{ { SrTiO}_{3 } }}(100) and Si(100) substrates by dipping-pyrolysis pro-cess using metal naphthenates as starting materials. crystallinity and in-phase alignment of the films were analyzed by X-ray diffraction $\theta$-2$\theta$ scans and $\beta$ scans (pole-figures) respectively. Highly c-axis-oriented {{{{ { { {Bi }_{4 }Ti }_{3 }O }_{12 } }} thin films with smooth surfaces were obtained after heat treatment at 75$0^{\circ}C$ on {{{{ { SrTiO}_{3 } }}(100) sub-strate while the films grown of Si(100) exhibited polycrstalline characteristics. C-axis oriented film show-ed an epitaxial relationship with the {{{{ { SrTiO}_{3 } }} substrate.

• Electrical & Electronic Materials
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• v.10 no.10
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• pp.1034-1040
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• 1997

A solar cell conversion effiency was degraded by grain boundary effect in polycrystalline silicon. Grain boundaries acted as potential barriers as well as recombination centers for the photo-generated carriers. To reduce these effects of the grain boundaries we investigated various influencing factors such as emitter thickness thermal treatment preferential chemical etching of grain boundaries grid design contact metal and top metallization along boundaries. Pretreatment in $N_2$atmosphere and gettering by POCl$_3$and Al were performed to obtain multicrystalline silicon of the reduced defect density. Structural electrical and optical properties of slar cells were characterized before and after each fabrication process. Improved conversion efficiencies of solar cell were obtained by a combination of pretreatment above 90$0^{\circ}C$ emitter layer of 0.43${\mu}{\textrm}{m}$ Al diffusion in to grain boundaries on rear side fine grid finger top Yb metal and buried contact metallization along grain boundaries.