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Pressure dependence of the band gap energy for the dilute nitride GaNxAs1−x

Zhao C.-Z., Wei T., Sun X.-D., Wang S.-S., Lu K.-Q.

Materials Science Poland

2016

Vol. 34, No. 4

881--885

A model is developed to describe the pressure dependence of the band gap energy for the dilute nitride GaNxAs1-x. It is found that the sublinear pressure dependence of E- is due to the coupling interaction between E+ and E-. We have also found that GaNxAs1-xneeds much larger pressure than GaAs to realize the transition from direct to indirect band gap. It is due to two factors. One is the coupling interaction between the E+ and E-. The other is that the energy difference between the X conduction band minimum (CBM) and the G CBM in GaNxAs1-x is larger than that in GaAs. In addition, we explain the phenomenon that the energy difference between the X CBM and the G CBM in GaNxAs1-xis larger than that in GaAs. It is due to the impurity-host interaction.

Influence of pressure on dynamic viscosity of oil

Czaban A., Frycz M.

Journal of KONES

2013

Vol. 20, No. 2

49--54

The viscosity of lubricant is physical quantity, which has major impact on slide bearings and micro-bearings functioning parameters. Applying computer simulations as a tool to study the hydrodynamic lubrication phenomenon, researcher should create a computational model as close as possible to the real object, therefore the knowledge about a viscosity dependence on temperature and shear rate of bearing lubricating oil is essential in simulations of slide bearings hydrodynamic lubrication. This paper present research, which show, that also an influence of pressure on oil dynamic viscosity should be taken into consideration. The aim of this work is to determine the influence of pressure on the dynamic viscosity of lubricating oil. In this research the selected new and used engine oils were investigated. The dynamic viscosity of oil was measured at different pressures and temperatures in the function of shear rate. In this work the engine oils of passenger vehicles were investigated. The viscosity measurements for new and used lubricating oils were made with the Thermo Scientific Haake Mars III rheometer. The received information will be used in the simulations of hydrodynamic lubrication of slide bearings and microbearings. Fitting viscosity curves, described by a viscosity model adopted in simulations, to the experimental data, obtained for motor oils, will allow to find the values of coefficients of that model. The determined coefficients will be set in the relationship defined by the adopted viscosity model, implemented in the used for simulations CFD software. Collected data may also be useful for designing bearings and sliding friction pairs.