scholarly journals Limitations during Vapor Phase Growth of Bulk (100) 3C-SiC Using 3C-SiC-on-SiC Seeding Stacks

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2353
Author(s):  
Philipp Schuh ◽  
Johannes Steiner ◽  
Francesco La Via ◽  
Marco Mauceri ◽  
Marcin Zielinski ◽  
...  
Keyword(s):  
Temperature Gradient ◽  
Gas Phase ◽  
Phase Growth ◽  
Vertical Temperature ◽  
Simulation Data ◽  
Bulk Growth ◽  
Growth Increase ◽  
Maximal Thickness ◽  
High Supersaturation ◽  
Transfer Method

The growth of 3C-SiC shows technological challenges, such as high supersaturation, a silicon-rich gas phase and a high vertical temperature gradient. We have developed a transfer method creating high-quality 3C-SiC-on-SiC (100) seeding stacks, suitable for use in sublimation “sandwich” epitaxy (SE). This work presents simulation data on the change of supersaturation and the temperature gradient between source and seed for the bulk growth. A series of growth runs on increased source to seed distances was characterized by XRD and Raman spectroscopy. Results show a decrease in quality in terms of single-crystallinity with a decrease in supersaturation. Morphology analysis of as-grown material indicates an increasing protrusion dimension with increasing thickness. This effect limits the achievable maximal thickness. Additional polytype inclusions were observed, which began to occur with low supersaturation (S ≤ 0.06) and prolonged growth (increase of carbon gas-species).

scholarly journals SIMULATION OF SINGLE CRYSTAL ONE DIMENSIONAL ZnO RODS ARRAY GROWTH PROCESS

2021 ◽  
Author(s):  
Andrey Sharapov ◽  
Igor Matyushkin
Keyword(s):  
Zinc Oxide ◽  
Single Crystal ◽  
Gas Phase ◽  
Growth Process ◽  
Silicon Oxide ◽  
Phase Growth ◽  
One Dimensional ◽  
Zno Rods

In this work, the formation of zinc oxide arrows by gas-phase growth on the surface of silicon oxide is simulated.

Numerical Simulation of Temperature Distribution in a Containment Vessel of an Operating PWR Plant

2015 ◽  
Vol 1 (1) ◽  
Author(s):  
Yoichi Utanohara ◽  
Michio Murase ◽  
Akihiro Masui ◽  
Ryo Inomata ◽  
Yuji Kamiya
Keyword(s):  
Numerical Simulation ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Heat Release ◽  
Gas Phase ◽  
Large Temperature ◽  
Measured Temperature ◽  
Average Temperature ◽  
Containment Vessel ◽  
Large Temperature Gradient

The structural integrity of the containment vessel (CV) for a pressurized water reactor (PWR) plant under a loss-of-coolant accident is evaluated by a safety analysis code that uses the average temperature of gas phase in the CV during reactor operation as an initial condition. Since the estimation of the average temperature by measurement is difficult, this paper addressed the numerical simulation for the temperature distribution in the CV of an operating PWR plant. The simulation considered heat generation of the equipment, the ventilation and air conditioning systems (VAC), heat transfer to the structure, and heat release to the CV exterior based on the design values of the PWR plant. The temperature increased with a rise in height within the CV and the flow field transformed from forced convection to natural convection. Compared with the measured temperature data in the actual PWR plant, predicted temperatures in the lower regions agreed well with the measured values. The temperature differences became larger above the fourth floor, and the temperature inside the steam generator (SG) loop chamber on the fourth floor was most strongly underestimated, −16.2  K due to the large temperature gradient around the heat release equipment. Nevertheless, the predicted temperature distribution represented a qualitative tendency, low at the bottom of the CV and increases with a rise in height within the CV. The total volume-averaged temperature was nearly equal to the average gas phase temperature. To improve the predictive performance, parameter studies regarding heat from the equipment and the reconsideration of the numerical model that can be applicable to large temperature gradient around the equipment are needed.

Characteristics of gas-saturated deposits of the Kandalaksha bay, the White Sea, according to the seismic-acoustic and litho-geochemical studies

2019 ◽  
pp. 107-114
Author(s):  
M. Yu. Tokarev ◽  
E. N. Poludetkina ◽  
A. V. Starovoytov ◽  
A. S. Pirogova ◽  
S. R. Korost ◽  
...  
Keyword(s):  
Organic Matter ◽  
Gas Phase ◽  
White Sea ◽  
Sedimentary Sequence ◽  
The White Sea ◽  
Glacial Sediments ◽  
Kandalaksha Bay ◽  
Maximal Thickness ◽  
Kandalaksha Gulf ◽  
Geochemical Studies

The article discusses the results of complex geological, geophysical and geochemical studies of gas-saturated sediments within the Kandalaksha gulf, the White Sea. As a part of the marine study detailed seismoacoustic studies were conducted, resulting in the geometry of the seabed, the distribution of geological peculiarities of the sedimentary sequence, including the zones of focused unloading of hydrocarbon fluids. It is shown that assemblages of the «gas caps» are confined to the zones of maximal thickness of post-glacial sediments. The composition of the organic matter in the sediments and the gas phase has been studied in detail.

Gas-phase synthesis of single crystals of Ge–Si system

2020 ◽  
Vol 34 (19) ◽  
pp. 2050178
Author(s):  
Aynur I. Hashimova
Keyword(s):  
Temperature Gradient ◽  
Single Crystals ◽  
Gas Phase ◽  
Vapor Phase ◽  
Solid Solutions ◽  
Closed Volume ◽  
Phase Synthesis ◽  
Polycrystalline Layer ◽  
Cold Zone ◽  
Hot Zone

In this study, the synthesis of single crystals of solid solutions Ge[Formula: see text]Si[Formula: see text] from the gas phase was performed in two different variants. Here, the vapor phase is created in a closed volume. A special ampoule has been made for this purpose. Ge–Si is placed near one end of the ampoule. A temperature gradient is created along the ampoule. The temperature of the hot zone was chosen to be [Formula: see text]C and the temperature of the cold zone to be [Formula: see text]C. It has been found that single crystals can form not only on the polycrystalline layer, but also from separate centers on the walls of the ampoule.

scholarly journals Experimental Study of the Temperature Distribution in CRTS-II Ballastless Tracks on a High-Speed Railway Bridge

2020 ◽  
Vol 10 (6) ◽  
pp. 1980 ◽  
Author(s):  
Lei Zhao ◽  
Ling-Yu Zhou ◽  
Guang-Chao Zhang ◽  
Tian-Yu Wei ◽  
Akim D. Mahunon ◽  
...  
Keyword(s):  
High Temperature ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
High Speed ◽  
Railway Track ◽  
Vertical Temperature ◽  
High Speed Railway ◽  
Extreme High Temperature ◽  
Transverse Temperature ◽  
Temperature Test

To study the temperature distribution in the China Railway Track System Type II ballastless slab track on a high-speed railway (HSR) bridge, a 1:4 scaled specimen of a simply-supported concrete box girder bridge with a ballastless track was constructed in laboratory. Through a rapid, extreme high temperature test in winter and a conventional high temperature test in summer, the temperature distribution laws in the track on the HSR bridge were studied, and the vertical and transverse temperature distribution trend was suggested for the track. Firstly, the extreme high temperature test results showed that the vertical temperature and the vertical temperature difference distribution in the track on HSR bridge were all nonlinear with three stages. Secondly, the extreme high temperature test showed that the transverse temperature distribution in the track was of quadratic parabolic nonlinear form, and the transverse temperature gradient in the bottom base was significantly higher than that of the other layers of the track. Thirdly, the three-dimensional temperature distribution in the track on HSR bridge was a nonlinear, three-stage surface. Furthermore, similar regularities were also obtained in the conventional high temperature test, in which the temperature span ranges were different from those of the extreme high temperature test. In addition, the conventional high temperature test also showed that under the natural environment conditions, the internal temperature gradient in the track layers changed periodically (over a period of 24 h).

Effects of Age and Overhead Illumination on Temperatures Preferred by Underyearling Rainbow Trout, Salmo gairdneri, in a Vertical Temperature Gradient

1978 ◽  
Vol 35 (11) ◽  
pp. 1430-1433 ◽  
Author(s):  
Wen-Hwa Kwain ◽  
Robert W. McCauley
Keyword(s):  
Rainbow Trout ◽  
Temperature Gradient ◽  
Temperature Gradients ◽  
Salmo Gairdneri ◽  
Vertical Temperature Gradient ◽  
Temperature Preference ◽  
Vertical Temperature ◽  
Preferred Temperature ◽  
Distribution Of Fish ◽  
Vertical Gradients

During their first 12 mo of life rainbow trout, Salmo gairdneri, preferred progressively cooler temperatures as they grew older; 19 °C was selected during the 1st mo and the selected temperature declined by intervals of 0.5 °C for each of the following months up to the 3rd mo. Fish swam higher in temperature gradients exposed to overhead illumination than in those in total darkness. This trend was reversed during the following 9 mo. These findings demonstrate the important role that age plays in the temperature preference of this species and the influence that overhead light may have on the distribution of fish in vertical gradients. Key words: preferred temperature, age, Salmo gairdneri, light gradients

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