scholarly journals Dendritic Growth in Si1−xGex Melts

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 761
Author(s):  
Genki Takakura ◽  
Mukannan Arivanandhan ◽  
Kensaku Maeda ◽  
Lu-Chung Chuang ◽  
Keiji Shiga ◽  
...  
Keyword(s):  
Dendritic Growth ◽  
Elevated Temperatures ◽  
Electronic Devices ◽  
Solidification Process ◽  
Dendrite Growth ◽  
In Situ Observation ◽  
Wide Range ◽  
Solidification Processes ◽  
Semiconductor Alloy

We investigated the types of dendrites grown in Si1−xGex (0 < x < 1) melts, and also investigated the initiation of dendrite growth during unidirectional growth of Si1-xGex alloys. Si1−xGex (0 < x < 1) is a semiconductor alloy with a completely miscible-type binary phase diagram. Therefore, Si1−xGex alloys are promising for use as epitaxial substrates for electronic devices owing to the fact that their band gap and lattice constant can be tuned by selecting the proper composition, and also for thermoelectric applications at elevated temperatures. On the other hand, regarding the fundamentals of solidification, some phenomena during the solidification process have not been clarified completely. Dendrite growth is a well-known phenomenon, which appears during the solidification processes of various materials. However, the details of dendrite growth in Si1−xGex (0 < x < 1) melts have not yet been reported. We attempted to observe dendritic growth in Si1−xGex (0 < x < 1) melts over a wide range of composition by an in situ observation technique. It was found that twin-related dendrites appear in Si1−xGex (0 < x < 1) melts. It was also found that faceted dendrites can be grown in directional solidification before instability of the crystal/melt interface occurs, when a growing crystal contains parallel twin boundaries.

In Situ Observation of Macro and Micro Solidification Process in the Molten Pool during Laser Remelting

Applied laser ◽  
2015 ◽  
Vol 35 (1) ◽  
pp. 20-24
Author(s):  
王永辉 Wang Yonghui ◽  
林鑫 Lin Xin ◽  
王理林 Wang Lilin ◽  
杨海欧 Yang Haiou ◽  
黄卫东 Huang Weidong
Keyword(s):  
Molten Pool ◽  
Solidification Process ◽  
In Situ Observation ◽  
Laser Remelting

Dendrite Grow up Relations with Cooling Speed

2013 ◽  
Vol 750-752 ◽  
pp. 473-476
Author(s):  
Qing Jun Zhang ◽  
Chun Liang Yan ◽  
Zhi Min Cui ◽  
Yao Guang Wu
Keyword(s):  
Cooling Rate ◽  
Structure Refinement ◽  
Dendritic Structure ◽  
Solidification Process ◽  
Confocal Laser ◽  
In Situ Observation ◽  
Dendrite Formation ◽  
Cooling Speed ◽  
Infrared Heater

Using confocal laser microscope with an infrared heater for 45 steel under different rate of solidification dendrite formation in the process of in situ observation, in the melt solidification phase has different cooling rate the cooling of dendrite formation, analysis of cooling rate on final solidified structure. Results show that with the reduction of temperature in the solidification process dendrite growth continuously, new nuclear has been formed, with the speeding up of the cooling rate, the dendritic structure refinement.

Using a Moderate Vacuum, Hot/Cryo-Stage Equipped AFM for In-Situ Observation of α-Phase Growth In 60SN40PB Hypoeutectic Solder

1998 ◽  
Vol 4 (S2) ◽  
pp. 316-317
Author(s):  
D. N. Leonard ◽  
P.E. Russell
Keyword(s):  
Surface Science ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
Scanning Tunneling ◽  
In Situ Observation ◽  
Atmospheric Conditions ◽  
Tunneling Microscopy ◽  
Wide Range ◽  
Gas Environment

Atomic force microscopy (AFM) was introduced in 1984, and proved to be more versatile than scanning tunneling microscopy (STM) due to the AFM's capabilities to scan non-conductive samples under atmospheric conditions and achieve atomic resolution. Ultra high vacuum (UHV) AFM has been used in surface science applications when control of oxidation and corrosion of a sample's surface are required. Expensive equipment and time consuming sample exchanges are two drawbacks of the UHV AFM system that limit its use. Until recently, no hot/cryo-stage, moderate vacuum, controlled gas environment AFM was commonly available.We have demonstrated that phase transformations are easily observable in metal alloys and polymers with the use of a moderate vacuum AFM that has in-situ heating/cooling capabilities and quick (within minutes) sample exchange times. This talk will describe the results of experiments involving a wide range of samples designed to make use of the full capabilities of a hot/cryo-stage, controlled gas environment AFM.

scholarly journals ANNEALING OF POLYCRYSTALLINE THIN FILM SILICON SOLAR CELLS IN WATER VAPOUR AT SUB-ATMOSPHERIC PRESSURES

2014 ◽  
Vol 54 (5) ◽  
pp. 341-347
Author(s):  
Peter Pikna ◽  
Vlastimil Píč ◽  
Vítězslav Benda ◽  
Antonín Fejfar
Keyword(s):  
Thin Film ◽  
Solar Cells ◽  
Solar Cell ◽  
Water Vapour ◽  
Elevated Temperatures ◽  
Voltage Response ◽  
In Situ Observation ◽  
Polycrystalline Thin Film ◽  
Cell Parameters

Thin film polycrystalline silicon (poly-Si) solar cells were annealed in water vapour at pressures below atmospheric pressure. PN junction of the sample was contacted by measuring probes directly in the pressure chamber filled with steam during passivation. Suns-VOC method and a Lock-in detector were used to monitor an effect of water vapour to VOC of the solar cell during whole passivation process (in-situ). Tested temperature of the sample (55°C – 110°C) was constant during the procedure. Open-circuit voltage of a solar cell at these temperatures is lower than at room temperature. Nevertheless, voltage response of the solar cell to the light flash used during Suns-VOC measurements was good observable. Temperature dependences for multicrystalline wafer-based and polycrystalline thin film solar cells were measured and compared. While no significant improvement of thin film poly-Si solar cell parameters by annealing in water vapour at under-atmospheric pressures was observed up to now, in-situ observation proved required sensitivity to changing VOC at elevated temperatures during the process.

Investigating the Relationships Between Structures and Properties of Al Alloys Incorporated With Ti and Mg Inclusions

2016 ◽  
Vol 138 (3) ◽  
Author(s):  
Halil Ibrahim Kurt ◽  
Ibrahim H. Guzelbey ◽  
Serdar Salman ◽  
Razamzan Asmatulu ◽  
Mustafa Dere
Keyword(s):  
Solid Solution ◽  
Grain Size ◽  
Elevated Temperatures ◽  
Solidification Process ◽  
Optical Microscope ◽  
Industrial Applications ◽  
Al Alloys ◽  
Average Grain Size ◽  
Solidification Processes ◽  
Grain Size And Shape

This study investigates the influence of titanium (Ti) and magnesium (Mg) additions on aluminum (Al) alloys in order to evaluate the relationship between the structure and properties of the new alloys. The alloys obtained at elevated temperatures mainly consist of Al–2Mg–1Ti, Al–2Mg–3Ti, Al–4Mg–2Ti, and Al–6Mg–2Ti alloys, as well as α and τ solid solution phases of intermetallic structures. Microstructural analyses were performed using X-ray diffraction (XRD), optical microscope, and energy dispersive spectrometry (EDS) techniques. Test results show that the average grain size of the alloys decreased with the addition of Ti inclusions during the casting and solidification processes, and the smallest grain size was found to be 90 μm for the Al–6Mg–3Ti alloy. In addition, tensile properties of the Al–Mg–Ti alloys were initially improved and then worsened after the addition of higher concentrations of Ti. The highest tensile and hardness values of the alloys were Al–4Mg–2Ti (205 MPa) and Al–6Mg–3Ti (80 BHN). The primary reasons for having higher mechanical properties may be attributed to strengthening of the solid solution and refinement of the grain size and shape during the solidification process. For this study, the optimum concentrations of Ti and Mg added to the Al alloys were 4 and 2 wt.%, respectively. This study may be useful for field researchers to develop new classes of Al alloys for various industrial applications.

In Situ Observation of Solidification Process of AISI 304 Austenitic Stainless Steel

2008 ◽  
Vol 15 (6) ◽  
pp. 78-82 ◽  
Author(s):  
Fu-xiang Huang ◽  
Xin-hua Wang ◽  
Jiong-ming Zhang ◽  
Chen-xi Ji ◽  
Yuan Fang ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Solidification Process ◽  
In Situ Observation ◽  
Aisi 304 ◽  
304 Austenitic Stainless Steel

scholarly journals In situ observation of cracking and self-healing of solid electrolyte interphases during lithium deposition

2020 ◽  
Author(s):  
Tingting Yang ◽  
Hui Li ◽  
Yongfu Tang ◽  
Jingzhao Chen ◽  
Hongjun Ye ◽  
...  
Keyword(s):  
Solid Electrolyte ◽  
Solid Electrolyte Interphase ◽  
Dendrite Growth ◽  
In Situ Observation ◽  
Self Healing ◽  
Directional Growth ◽  
Transmission Electron ◽  
In Situ Observations ◽  
Li Batteries

Abstract The growth of lithium (Li) whiskers is detrimental to Li batteries. However, it remains a challenge to directly track Li whisker growth. Here we report in situ observations of electrochemically induced Li deposition under a CO2 atmosphere inside an environmental transmission electron microscope. We find that the morphology of individual Li deposits is strongly influenced by the competing processes of cracking and self-healing of the solid electrolyte interphase (SEI). When cracking overwhelms self-healing, the directional growth of Li whiskers predominates. In contrast, when self-healing dominates over cracking, the isotropic growth of round Li particles prevails. The Li deposition rate and SEI constituent can be tuned to control the Li morphologies. We reveal a new “weak-spot” mode of Li dendrite growth, which is attributed to the operation of the Bardeen-Herring growth mechanism in the whisker’s cross section. This work has implications for the control of Li dendrite growth in Li batteries.

Microscopic Observations of SOFC Anodes Under Operation With Hydrocarbon Fuels

2004 ◽  
Author(s):  
Tatsuya Kawada ◽  
Keiji Yashiro ◽  
Tomoaki Taura ◽  
Kenichiro Takeda ◽  
Atsushi Kaimai ◽  
...  
Keyword(s):  
Elevated Temperatures ◽  
Carbon Deposition ◽  
Optical Microscope ◽  
Open Circuit ◽  
In Situ Observation ◽  
Nickel Surface ◽  
Operation Condition ◽  
Grid Electrode ◽  
Laser Raman

Carbon deposition on a SOFC anode was investigated under direct hydrocarbon fueling condition. Microscopic behaviors were observed with a newly designed sample holder that enabled in-situ observation of an electrode in operation under controlled atmosphere at elevated temperatures. The preferential carbon deposition site, the structure of the deposited carbon, and the chemical or electrochemical re-oxidation processes were investigated with an optical microscope combined with a laser Raman microscope. Color and morphology change of the electrode surface was recorded with a CCD camera, and the deposited materials were identified with a laser Raman microscope. A nickel micro grid was used as a model electrode of a well-defined microstructure. When the cell was kept at an open circuit condition in methane, carbon started to deposit on the surface of Ni grid electrode. The deposition of carbon was clearly observed as the change in the reflection on the nickel surface by optical microscope as well as by the appearance of the specific peak at ∼ 1560 cm−1 in Raman spectroscopy. The deposited carbon was in the form of graphite on the nickel grid electrode. The carbon coverage on the surface was not uniform but varied from grain to grain. When a certain anodic overpotential (e.g. 200 mV) was applied to the electrode, the carbon disappeared gradually from the edge of the electrode i.e. from the electrode/electrolyte boundary where oxygen was supplied electrochemically. It is the first in-situ observation of the electrochemical carbon oxidation in a real operation condition.

In situ observation of Si faceted dendrite growth from low-degree-of-undercooling melts

2008 ◽  
Vol 56 (11) ◽  
pp. 2663-2668 ◽  
Author(s):  
Kozo Fujiwara ◽  
Kensaku Maeda ◽  
Noritaka Usami ◽  
Gen Sazaki ◽  
Yoshitaro Nose ◽  
...  
Keyword(s):  
Dendrite Growth ◽  
In Situ Observation ◽  
Low Degree ◽  
Faceted Dendrite
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