scholarly journals Use of Growth-Rate/Temperature-Gradient Charts for Defect Engineering in Crystal Growth from the Melt

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 909
Author(s):  
Thierry Duffar
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Temperature Gradient ◽  
Growth Conditions ◽  
Industrial Applications ◽  
Physical Models ◽  
Production Yield ◽  
Defect Engineering ◽  
Pedagogic Tool ◽  
Simple Growth

As the requirements in terms of crystal defect/quality and production yield are generally contradictory, it is necessary to develop methods in order to find the best compromise for the growth conditions of a given crystal. Simple growth-rate/temperature-gradient charts are a possible tool in this respect. After the recall of the classical analytical equations useful for describing the process and defect engineering, a simple pedagogic case explains the building and use of such charts. The more complex application to the directional casting of photovoltaic Si necessitated the development of new physical models for twinning and equiaxed growth. This allowed plotting charts that proved useful for industrial applications. The conclusions discuss the drawbacks and advantages of the method. It finally proves to be a pedagogic tool for teaching crystal growth engineering.

scholarly journals Macrodefects in Cubic Silicon Carbide Crystals

2010 ◽  
Vol 645-648 ◽  
pp. 375-378 ◽  
Author(s):  
Valdas Jokubavicius ◽  
Justinas Palisaitis ◽  
Remigijus Vasiliauskas ◽  
Rositza Yakimova ◽  
Mikael Syväjärvi
Keyword(s):  
Growth Rate ◽  
Silicon Carbide ◽  
Crystal Growth ◽  
High Temperature ◽  
Temperature Gradient ◽  
Early Stage ◽  
Growth Conditions ◽  
Temperature Ramp ◽  
Cubic Silicon Carbide ◽  
Sublimation Growth

Different sublimation growth conditions of 3C-SiC approaching a bulk process have been investigated with the focus on appearance of macrodefects. The growth rate of 3C-SiC crystals grown on 6H-SiC varied from 380 to 460 μm/h with the thickness of the crystals from 190 to 230 μm, respectively. The formation of macrodefects with void character was revealed at the early stage of 3C-SiC crystal growth. The highest concentration of macrodefects appears in the vicinity of the domain in samples grown under high temperature gradient and fastest temperature ramp up. The formation of macrodefects was related to carbon deficiency which appear due to high Si/C ratio which is used to enable formation of the 3C-SiC polytype.

Study on TlBr Single Crystal Growth Using Improved Electro Dynamic Gradient Method

2011 ◽  
Vol 415-417 ◽  
pp. 1979-1982
Author(s):  
Zhi Ping Zheng ◽  
Jing Wang ◽  
Lin Quan ◽  
Shu Ping Gong ◽  
Dong Xiang Zhou
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Electrical Properties ◽  
Temperature Gradient ◽  
Growth Conditions ◽  
Single Crystal Growth ◽  
Optical And Electrical Properties ◽  
X Ray Diffraction ◽  
X Ray

Electro Dynamic Gradient (EDG) method was utilized for TlBr crystal growth in this paper. The influence of crystal growth conditions such as temperature gradient and growth rate on optical and electrical properties of grown TlBr crystals was investigated. The quality of TlBr crystals was characterized by infrared (IR) transmittance spectrum, X-ray diffraction, and I-V measurements.

scholarly journals Influences of Powder Source Porosity on Mass Transport during AlN Crystal Growth Using Physical Vapor Transport Method

Crystals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1436
Author(s):  
Danyang Fu ◽  
Qikun Wang ◽  
Gang Zhang ◽  
Zhe Li ◽  
Jiali Huang ◽  
...  
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Mass Transport ◽  
Growth Conditions ◽  
Vapor Transport ◽  
Growth Chamber ◽  
Physical Vapor Transport ◽  
Rate Variation ◽  
Deposition Surface ◽  
Mass Transport Process

We developed a two-dimensional (2D) transport model to investigate mass transport during bulk AlN crystal growth via the physical vapor transport (PVT) process using the finite element method (FEM), taking the powder source porosity, buoyancy, and vapor diffusion into account. The porosity effects of the powder source on mass transport under various growth conditions were investigated in detail. The simulation results show that the porosity of the powder source significantly affects the mass transport process during AlN sublimation growth. When the porosity of the powder source decreases, the growth rate becomes more uniform along the seed deposition surface, although the sublimation rate and crystal growth rate decrease, which can be attributed to the reduced specific surface area of the powder source and the reduced flow rate of Al vapor in the powder source. A flat growth interface can be achieved at a porosity of 0.2 under our specific growth conditions, which in turn facilitate the growth of high-quality AlN crystals and better yield. The decomposition of the powder source and the transport of Al vapor in the growth chamber can be suppressed by increasing the pressure. In addition, the AlN growth rate variation along the deposition surface can be attributed to the Al vapor pressure gradient caused by the temperature difference in the growth chamber.

Modification of Crucible Shape in Top Seeded Solution Growth of SiC Crystal

2018 ◽  
Vol 924 ◽  
pp. 47-50
Author(s):  
Young Gon Kim ◽  
Su Hun Choi ◽  
Yun Ji Shin ◽  
Seong Min Jeong ◽  
Myung Hyun Lee ◽  
...  
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Temperature Gradient ◽  
Solution Growth ◽  
Cross Sectional ◽  
Dissolved Carbon ◽  
Simulation Results ◽  
Stable Growth ◽  
Top Seeded Solution Growth ◽  
Numerical Approaches

The modified crucible in the top seeded solution growth (TSSG) method was proposed to get the stable growth condition and the enhanced growth rate. The temperature gradient and the distribution of dissolved carbon in the solvent were obtained by numerical approaches. Compared simulation results and experiment, we investigated the region where is the most of dissolved carbon and it is supplied to the seed through what path. The cross-sectional samples of crucibles and grown SiC crystals were systematically analyzed to investigate the effect of the crucible modification on SiC crystal growth.

scholarly journals Depth-hoar crystal growth in the surface layer under high temperature gradient

1993 ◽  
Vol 18 ◽  
pp. 39-45 ◽  
Author(s):  
Takuya Fukuzawa ◽  
Eizi Akitaya
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
High Temperature ◽  
Temperature Gradient ◽  
Crystal Growth Rate ◽  
Snow Surface ◽  
Night Time ◽  
High Temperature Gradient ◽  
Series Of Experiments ◽  
The Given

The quick growth of depth-hoar crystals was observed at night-time just below the snow surface on a south-facing slope. This growth was due to a high temperature gradient (> 100 K m−1) near the snow surface under clear skies after a thin deposition of new snow on older and denser snow. The temperature gradient was greater when internal melting had taken place during daytime, keeping the sub-surface snow temperature at 0°C even after sunset until all liquid water had frozen. To understand the relationship between the crystal growth rate and the temperature gradient, a series of experiments was carried out in the laboratory. The snow sample was set under a constant temperature gradient between 100 and 300 K m− and sustained for about 50 h. The average crystal size increased linearly with time and the crystal growth rate increased as the given temperature gradient increased. The growth rates were in the order of 10−9 m s−1, which gave a good agreement with the results of the field observation.

scholarly journals Depth-hoar crystal growth in the surface layer under high temperature gradient

1993 ◽  
Vol 18 ◽  
pp. 39-45 ◽  
Author(s):  
Takuya Fukuzawa ◽  
Eizi Akitaya
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
High Temperature ◽  
Temperature Gradient ◽  
Crystal Growth Rate ◽  
Snow Surface ◽  
Night Time ◽  
High Temperature Gradient ◽  
Series Of Experiments ◽  
The Given

The quick growth of depth-hoar crystals was observed at night-time just below the snow surface on a south-facing slope. This growth was due to a high temperature gradient (> 100 K m−1) near the snow surface under clear skies after a thin deposition of new snow on older and denser snow. The temperature gradient was greater when internal melting had taken place during daytime, keeping the sub-surface snow temperature at 0°C even after sunset until all liquid water had frozen. To understand the relationship between the crystal growth rate and the temperature gradient, a series of experiments was carried out in the laboratory. The snow sample was set under a constant temperature gradient between 100 and 300 K m− and sustained for about 50 h. The average crystal size increased linearly with time and the crystal growth rate increased as the given temperature gradient increased. The growth rates were in the order of 10−9 m s−1, which gave a good agreement with the results of the field observation.

scholarly journals Microstructural Evolution And Mechanical Properties of FCAW Joints In 9% Ni Steel Prepared With Two Types of Ni-Based Weld Metals

2022 ◽  
Author(s):  
Jiyong Hwang ◽  
Kwangsu Choi ◽  
Sang Min Lee ◽  
Hyo Yun Jung
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Temperature Gradient ◽  
Weld Metal ◽  
Crystal Growth Rate ◽  
Inconel 625 ◽  
Large Temperature ◽  
Joint Interface ◽  
Weld Metals ◽  
Flux Cored Arc Welding

Abstract The microstructural and mechanical evaluation of 9% Ni steel with Flux-Cored Arc Welding was performed with two different Ni-based weld metals: Inconel 625 and Hastelloy 609. Weld metals showed the microstructural change depending on the temperature gradient and crystal growth rate for each region during the cooling after welding. At the bottom of the weld metal, which is rapidly cooled in contact with the cold base metal, a cellular/planar growth was exhibited due to a large temperature gradient and low crystal growth rate. While, columnar dendrites were exhibited in the central region cooled relatively slowly and precipitates were observed in the interdendritic region. In the low-temperature toughness test, the absorbed impact energies were 89 and 55 J for Inconel 625 and Hastelloy 609, respectively. When Inconel 625 is used as the weld metal compared to Hastelloy 609, the high content of the γ stabilizer and martensite start temperature decreasing elements leads to the formation of a thicker γ-phase layer and thinner martensite layer in the transition region. In addition, high content of these elements suppresses the martensite transformation and maintains the stability of the weld joint interface even at low temperatures, resulting in the higher absorbed impact energy.

TEMPERATURE DEPENDENCE OF THE CRYSTAL GROWTH RATE IN POLAR GLACIERS

1987 ◽  
Vol 48 (C1) ◽  
pp. C1-661-C1-662 ◽  
Author(s):  
J. R. PETIT ◽  
P. DUVAL ◽  
C. LORIUS
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Temperature Dependence ◽  
Crystal Growth Rate

Comparison of copper sulphate pentahydrate growth rates determined by different methods

1990 ◽  
Vol 55 (7) ◽  
pp. 1691-1707 ◽  
Author(s):  
Miloslav Karel ◽  
Jiří Hostomský ◽  
Jaroslav Nývlt ◽  
Axel König
Keyword(s):  
Growth Rate ◽  
Crystal Growth ◽  
Fluidized Bed ◽  
Growth Rates ◽  
Copper Sulphate ◽  
Crystal Growth Rate ◽  
Effect Of Temperature ◽  
Rotating Disc ◽  
Shape Factors ◽  
Data Treatment

Crystal growth rates of copper sulphate pentahydrate (CuSO4.5 H2O) determined by different authors and methods are compared. The methods included in this comparison are: (i) Measurement on a fixed crystal suspended in a streaming solution, (ii) measurement on a rotating disc, (iii) measurement in a fluidized bed, (iv) measurement in an agitated suspension. The comparison involves critical estimation of the supersaturation used in measurements, of shape factors used for data treatment and a correction for the effect of temperature. Conclusions are drawn for the choice of values to be specified when data of crystal growth rate measurements are published.

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