Control of Lamellar Orientation in γ-TiAl Based PST Crystal by Using Seed Crystals

ABSTRACTUnidirectional solidification of Ti-48Al binary alloy using γ-TiAl single-phase seed crystals has been carried out by an optical floating zone method. The lamellar orientation of the grown PST crystal follows the orientation of the Ti-57Al seed crystal, while it fails to follow that in the case of the Ti-53Al seed. Microstructure analysis reveals that the seed crystal of Ti-57Al exhibits a flat liquid/solid interface in melting (γ→+L) even after making contact with 48Al to grow, whereas the seed of Ti-53Al shows a cellular interface due to the peritectic reaction in melting (γ→α+L). At the 57/48 interface, an abrupt change of Al concentration was detected from the seed to the grown crystal, indicating an occurrence of composition travel to skip the peritectic reaction, which is responsible for the control of lamellar orientation of the grown PST crystals. The same attempt has been made by using the 57Al single crystal seed with a different orientation, and the lamellar orientation of the grown PST crystal was confirmed to follow the orientation of the seed.

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Axis symmetry of silicon molten zone interface shape under a mirror-shifting-type infrared convergent-heating floating-zone method

CrystEngComm ◽

10.1039/c5ce01685a ◽

2015 ◽

Vol 17 (48) ◽

pp. 9452-9458 ◽

Cited By ~ 2

Author(s):

Md. Mukter Hossain ◽

Satoshi Watauchi ◽

Masanori Nagao ◽

Isao Tanaka

Keyword(s):

Grown Crystal ◽

Molten Zone ◽

Interface Shape ◽

Floating Zone ◽

Zone Method ◽

Floating Zone Method ◽

L System

Axis symmetry of the silicon molten zone shape, which is dependent on the position of the mirror-lamp (M-L) system, is related to the shape of the grown crystal.

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Structural Characterization of Lateral-grown 6H-SiC a/m-plane Seed Crystals by Hot Wall CVD Epitaxy

MRS Proceedings ◽

10.1557/opl.2014.563 ◽

2014 ◽

Vol 1693 ◽

Author(s):

Ouloide Yannick Goue ◽

Balaji Raghothamachar ◽

Michael Dudley ◽

Andrew J. Trunek ◽

Philip G. Neudeck ◽

...

Keyword(s):

Grown Crystal ◽

Stacking Faults ◽

Chemical Vapor ◽

Growth Direction ◽

Seed Crystal ◽

Lateral Expansion ◽

X Ray ◽

Seed Crystals ◽

High Resolution Tem ◽

Crystal Fibers

ABSTRACTThe performance of commercially available silicon carbide (SiC) power devices is limited due to inherently high density of screw dislocations (SD), which are necessary for maintaining polytype during boule growth and commercially viable growth rates. The NASA Glenn Research Center (GRC) has recently proposed a new bulk growth process based on axial fiber growth (parallel to the c-axis) followed by lateral expansion (perpendicular to the c-axis) for producing multi-faceted m-plane SiC boules that can potentially produce wafers with as few as one SD per wafer. In order to implement this novel growth technique, the lateral homoepitaxial growth expansion of a SiC fiber without introducing a significant number of additional defects is critical. Lateral expansion is being investigated by hot wall chemical vapor deposition (HWCVD) growth of 6H-SiC a/m-plane seed crystals (0.8mm x 0.5mm x 15mm) designed to replicate axially grown SiC single crystal fibers. The post-growth crystals exhibit hexagonal morphology with approximately 1500 μm (1.5 mm) of total lateral expansion. Preliminary analysis by synchrotron white beam x-ray topography (SWBXT) confirms that the growth was homoepitaxial, matching the polytype of the respective underlying region of the seed crystal. Axial and transverse sections from the as-grown crystal samples were characterized in detail by a combination of SWBXT, transmission electron microscopy (TEM) and Raman spectroscopy to map defect types and distribution. X-ray diffraction analysis indicates the seed crystal contained stacking disorders and this appears to have been reproduced in the lateral growth sections. Analysis of the relative intensity for folded transverse acoustic (FTA) and optical (FTO) modes on the Raman spectra indicate the existence of stacking faults (SFs). Further, the density of stacking faults is higher in the seed than in the grown crystal. Bundles of dislocations are observed propagating from the seed in m-axis lateral directions. Contrast extinction analysis of these dislocation lines reveals they are edge type basal plane dislocations that track the growth direction. Polytype phase transition and stacking faults were observed by high-resolution TEM (HRTEM), in agreement with SWBXT and Raman scattering.

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Polytype and Crystal Quality of SiC Crystals Grown on 3C-SiC by Seeded Solution Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.615-617.27 ◽

2009 ◽

Vol 615-617 ◽

pp. 27-30 ◽

Cited By ~ 3

Author(s):

Kazuaki Seki ◽

Ryo Tanaka ◽

Toru Ujihara ◽

Yoshikazu Takeda

Keyword(s):

Growth Process ◽

Solution Method ◽

Grown Crystal ◽

Stacking Faults ◽

High Density ◽

Seed Crystal ◽

Solution Growth ◽

Crystal Quality ◽

Seed Crystals

We investigated the effects of the solution growth process on the polytype and crystal quality of the crystals grown on (111) 3C-SiC seed crystals. In spite of the use of 3C-SiC seed crystals, the polytype of the grown crystal changed from 3C-SiC to 6H-SiC, because the stacking errors easily occur due to the similarity of the (111) face of 3C-SiC and the (0001) face of 6H-SiC. Moreover, the grown 6H-SiC crystal affected the crystal quality of the seed crystal, i.e., high-density stacking faults were induced in the seed crystal after the growth process.

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Preparation and Characterization of Lead-Free (Ba0.4Sr0.4Ca0.2)(Zr0.05Ti0.95)O3 Ceramics Using BST Seed Induced Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.766.180 ◽

2018 ◽

Vol 766 ◽

pp. 180-185

Author(s):

Jiraporn Dangsak ◽

Sukum Eitssayeam ◽

Tawee Tunkasiri ◽

Uraiwan Intatha

Keyword(s):

Solid Solution ◽

Solid State ◽

Single Phase ◽

Seed Crystal ◽

Lead Free ◽

X Ray Diffraction ◽

Conventional Solid State Reaction ◽

X Ray ◽

Seed Crystals

The solid solution of lead-free (Ba0.4Sr0.4Ca0.2) (Zr0.05Ti0.95) O3 (BSCZT) ceramics were prepared from the seed induced method. The Ba0.6Sr0.4TiO3 (BST) were used as the seed crystals, they were prepared using the molten salt technique. The phase formation was examined using the X-ray diffraction technique (XRD). It was found that the single phase perovskite structure of BST was obtained at a temperature of 800°C. The ceramics were prepared using the conventional solid state reaction by adding of BST seed crystals at 2.5, 5, 7.5 and 10 mol%. The structure showed that a single phase perovskite was obtained after sintered at 1400 °C. This work confirmed that BST seed crystal successfully diffused into BSCZT ceramic and the BSCZT ceramic with a seed crystal showed higher dielectric than the BSCZT ceramic without seed crystals.

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NUMERICAL SIMULATION OF CRYSTAL GROWTH BY FLOATING ZONE METHOD

Advances in Computational Heat Transfer. Proceedings of the International Symposium ◽

10.1615/ichmt.1997.intsymliqtwophaseflowtranspphencht.580 ◽

1997 ◽

Author(s):

V. K. Artemyev ◽

N. V. Gusev ◽

T. M. Luhanova ◽

I. L. Ozernyh ◽

V. P. Shishulin ◽

...

Keyword(s):

Numerical Simulation ◽

Crystal Growth ◽

Floating Zone ◽

Zone Method ◽

Floating Zone Method

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Defect Optical and Scintillation Properties of Lu2Si2O7:Ce Single Crystal Grown by Floating Zone Method

Journal of Inorganic Materials ◽

10.3724/sp.j.1077.2013.12599 ◽

2013 ◽

Vol 28 (8) ◽

pp. 891-895

Author(s):

He FENG ◽

Guo-Hao REN ◽

Dong-Zhou DING ◽

Huan-Ying LI ◽

Jun XU ◽

...

Keyword(s):

Single Crystal ◽

Floating Zone ◽

Zone Method ◽

Floating Zone Method

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Photoluminescence, scintillation and thermoluminescence properties of Ce-doped SrLaAl3O7 crystals synthesized by the optical floating zone method

Optical Materials ◽

10.1016/j.optmat.2020.110782 ◽

2021 ◽

Vol 112 ◽

pp. 110782

Author(s):

Kenta Igashira ◽

Daisuke Nakauchi ◽

Takumi Kato ◽

Noriaki Kawaguchi ◽

Takayuki Yanagida

Keyword(s):

Floating Zone ◽

Zone Method ◽

Floating Zone Method

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Single-Crystal Growth of Sr2RuO4 by the Floating-Zone Method Using an Infrared Image Furnace with Improved Halogen Lamps

Crystals ◽

10.3390/cryst11040392 ◽

2021 ◽

Vol 11 (4) ◽

pp. 392

Author(s):

Naoki Kikugawa ◽

Dmitry A. Sokolov ◽

Tohru Nagasawa ◽

Andrew P. Mackenzie

Keyword(s):

Crystal Growth ◽

Single Crystal ◽

Infrared Image ◽

Single Crystal Growth ◽

Molten Zone ◽

Floating Zone ◽

Unconventional Superconductor ◽

Zone Method ◽

Floating Zone Method ◽

Halogen Lamps

We report the single-crystal growth of the unconventional superconductor Sr2RuO4, on which research has reached a turning point recently. In order to optimize the quality of crystals grown by the floating-zone method using an infrared image furnace, we focus on an improvement of the structure of the filament in the halogen lamps. By reducing the thickness of the total filament, the form of the molten zone was narrowed. More importantly, the molten zone was observed to be more stable during the growth process. Finally, we obtained the crystals with a length of 12 cm. Additionally, the grown crystal has high quality, displaying the 1.5 K transition temperature expected only for the purest crystals. We also discuss the availability of the newly developed halogen lamps.

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