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Aging characteristics of ZnS:Mn electroluminescent films grown by a chemical vapor deposition technique (1992)

Mikami, Akiyoshi ; Terada, Kousuke ; Okibayashi, Katsushi ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 72 (1992), S. 773-782

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: The stability of luminance-voltage characteristics (L-V) has been investigated on ZnS:Mn electroluminescent films grown by chemical vapor deposition. It is found that the aging pattern varies between the positive shift (P shift) and the negative shift (N shift) with the growth temperature. In both cases the L-V curve, the current-voltage relationship, and the symmetry of the light emission with respect to the voltage polarity are strictly cooperative during the aging process. The N shift appears to be dominant when the current is limited by electron injection from the interface, whereas the P shift becomes dominant under the bulk limited conduction, accompanying an excellent symmetry of the emission. A high-field-conduction characteristic in the ZnS layer, which is a decisive factor to determine the aging pattern, is significantly affected by its stoichiometry, grain size, and impurity content. It has been further clarified that the N shift consists of the combination of a softening and a shifting in the L-V relation, which are defined as the effect due to the asymmetric polarization and the band bending in the ZnS layer, respectively. This study demonstrates a stable L-V characteristic without shifting the threshold voltage. The difference between the P shift and the N shift is discussed on the basis of the crystalline property and the carrier transport mechanism.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.351810

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Numerical simulation of blow molding - Viscoelastic flow analysis of parison formation (1995)

Tanoue, Shuichi ; Kuwano, Yoshifumi ; Kajiwara, Toshihisa ; [et al.]

Stamford, Conn. [u.a.] : Wiley-Blackwell

Polymer Engineering and Science 35 (1995), S. 1546-1554

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ISSN: 0032-3888

Keywords: Chemistry ; Chemical Engineering

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: The simulation of the parison formation process in blow molding has been studied. The flow field was divided into two regions, namely, the extrudate swell region near the die lip and the parison formation region after the exit swell. In the swell region, we predicted the swelling ratio and residual stress distribution for high Weissenberg numbers for steady planar well using the 1-mode Giesekus model. In the parison formation region, the flow is assumed to be an unsteady unaxial elongational flow including drawdown and recoverable swell and is modeled using the 10-mode Giesekus model. We calculated the time course of parison length and thickness distribution, and compare the calculation results of parison length with experimental data. It was found that the predicted values agreed rather well with the experimental values. The calculation results could especially predict the shrink-back, which is the phenomenon where the parison length becomes shorter after the cessation of extrusion, and it was found tat this was caused by the recoverable swell of the parison, which depends on the tensile stress generation in the die. Various flow rates and die geometries were studied and confirmed the reliability and usefulness of the method.

Additional Material: 16 Ill.