Thermodynamic Analysis of Impurities in the Sublimation Growth of AlN Single Crystals

2006 ◽  
Vol 955 ◽  
Author(s):  
Li Du ◽  
James H Edgar
Keyword(s):  
Crystal Growth ◽  
Partial Pressure ◽  
Single Crystals ◽  
High Temperatures ◽  
Thermodynamic Analysis ◽  
Vapor Phase ◽  
Graphite Furnace ◽  
Main Species ◽  
Carbon Species ◽  
Sublimation Growth

ABSTRACTThe vapor phase species responsible for the transport of impurities in the sublimation-recondensation growth of bulk AlN crystals was predicted by thermodynamic analysis. AlN powder containing oxygen was investigated in Al-O-N system for an inert reactor. Dialuminum monoxide (Al2O) is strongly favored over all other possible oxygen containing species including NO and NO2. For AlN crystal growth in a graphite furnace, the Al-O-C-N system was studied. CO is the main species containing carbon and oxygen, and has a partial pressure more than one hundred times higher than all other carbon or oxygen containing species. Its partial pressure even exceeds that of Al vapor. Pure AlN growth on SiC seed was represented in the Al-N-Si-C system. SiC is not stable at high temperatures, the presence of nitrogen accelerates the decomposition of the SiC, and the most probable volatile silicon and carbon species originating from the SiC seed are Si, CN and C2N2.

Single-crystal growth and characterization of the Pb0.5Sr2.5Y1−xCaxCu2Oy system

1995 ◽  
Vol 10 (9) ◽  
pp. 2211-2215 ◽  
Author(s):  
H. Jin ◽  
N.L. Wang ◽  
Y. Chong ◽  
M. Deng ◽  
L.Z. Cao ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Single Crystals ◽  
Single Crystal Growth ◽  
Optimum Conditions ◽  
Flux Method ◽  
Ca Doping ◽  
Spontaneous Nucleation

Two kinds of methods such as spontaneous nucleation from flux-free stoichiometric melt and CuO flux method have been used for the growth of Pb0.5Sr2.5Y1−xCaxCu2Oy single crystals. The morphologies, phases, and compositions occurring in the crystals grown from the two kinds of methods were compared systematically. Optimum conditions for the growth of larger 1212 phase single crystals are x =0.15, 0.25, and 0.35. The lattice parameters of the crystals with the 1212 phase were found to be increasing upon Ca doping. The resistivity behavior of the PbSrYCaCuO single crystals with the 1212 phase both in the state of as-grown and after extended annealings under various oxygen partial pressure was also discussed briefly.

Single Crystal Growth of YBa2Cu4O8 and Y2Ba4Cu7O15 Under High Oxygen Pressure

1991 ◽  
Vol 251 ◽  
Author(s):  
T. Miyatake ◽  
T. Takata ◽  
K. Yamaguchi ◽  
K. Takamuku ◽  
N. Koshizuka ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Single Crystal ◽  
Single Crystals ◽  
Oxygen Pressure ◽  
Maximum Size ◽  
Single Crystal Growth ◽  
Mixed Gas ◽  
High Oxygen Pressure

ABSTRACTWe investigate the crystal growth of YBa2Cu4O8 (124) and Y2Ba4Cu7O15 (247) in Al2O3 crucibles at an oxygen partial pressure of 20MPa employing an O2- HIP apparatus in a mixed gas environment of Ar-20%O2. Various melts compositions, rich in Ba and Cu, are explored to optimize crystal growth of 124. Large 124 single crystals up to a size of 1×0.5×0.05mm3 are obtained from compositions with about 65˜67%CuO. 247 single crystals having a maximum size of 3×1.5×0.05mm3 are grown from the same composition of melts. 124 crystals exhibit superconductivity at 75K. 247 crystals show Tc of 20K.

Crystal growth of YBa2Cu3O7 by the SRL-CP method under low oxygen partial pressure atmosphere

1994 ◽  
Vol 9 (8) ◽  
pp. 1946-1951 ◽  
Author(s):  
M. Nakamura ◽  
Y. Yamada ◽  
Y. Shiohara
Keyword(s):  
Crystal Growth ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Single Crystals ◽  
Oxygen Pressure ◽  
Crystal Surface ◽  
Nitrogen Atmosphere ◽  
Low Oxygen ◽  
Pure Nitrogen ◽  
Rich Liquid

Single crystals of YBa2Cu3O7−x (Y123) were grown by a modified top-seeded crystal pulling method using a BaO-CuO solution with the solid Y2BaCuO5 (Y211) as a solute in an yttria crucible [the so-called solute-rich liquid crystal pulling (SRL-CP) method] under 2% oxygen partial pressure atmosphere [P(O2) = 0.02 atm]. According to the pseudo-binary phase diagrams of Lee and Lee,1 the temperature of Y123 crystal growth was expected to be lower for 0.02 atm oxygen pressure than for 0.21 atm oxygen pressure. The single crystals grown under P(O2) = 0.02 atm and cooled under the same atmosphere after the separation of crystal from a solution had twins near the microcracks on the crystal surface. On the other hand, the single crystals grown under P(O2) = 0.02 atm and cooled under pure nitrogen atmosphere (6N) showed no twin structure. These results indicate that twins did not form during crystal growth but formed due to tetragonal-orthorhombic transition as a consequence of oxygenation at cooling under low oxygen partial pressure.

scholarly journals Real-time x-ray studies of crystal growth modes during metal-organic vapor phase epitaxy of GaN on c- and m-plane single crystals

2014 ◽  
Vol 105 (5) ◽  
pp. 051602 ◽  
Author(s):  
Edith Perret ◽  
M. J. Highland ◽  
G. B. Stephenson ◽  
S. K. Streiffer ◽  
P. Zapol ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Single Crystals ◽  
Real Time ◽  
Vapor Phase ◽  
Vapor Phase Epitaxy ◽  
X Ray ◽  
Organic Vapor ◽  
Growth Modes ◽  
Metal Organic

Single crystal growth of cuprates from hydroxide fluxes

1997 ◽  
Vol 12 (5) ◽  
pp. 1210-1213 ◽  
Author(s):  
S. A. Sunshine ◽  
T. Siegrist ◽  
L. F. Schneemeyer
Keyword(s):  
Crystal Growth ◽  
Transition Metals ◽  
Single Crystal ◽  
Single Crystals ◽  
High Temperatures ◽  
Potassium Hydroxide ◽  
Single Crystal Growth ◽  
High Solubility ◽  
Hydroxide Fluxes ◽  
Perovskite Unit Cell

Barium and potassium hydroxide have been investigated as fluxes for the growth of cuprate single crystals. The relatively high solubility of transition metals and lanthanoids in these salt fluxes at moderate temperatures allows significant lowering of the growth temperatures required for many phases. Also, phases not stable at high temperatures become accessible. Two new cuprates have been prepared in the Ba–Ca–Cu–O and Ba–Y–Cu–O systems from a Ba(OH)2 · H2O flux. The compounds Ba3(Y0.23Cu0.77)2O5.78 and Ba3(Ca0.24Cu0.76)2O4.43 crystallize in a tetragonal (space group I4/mmm) oxygen deficient Sr3Ti2O7-type structure with lattice parameters a = 4.069(2) Å, 4.022(1) Å and c = 21.61(2) Å, 21.63(2) Å, respectively. The compound (Ba0.92Sr0.08) (Ca0.38Cu0.62)O2.1 crystallizes with a doubled perovskite unit cell along all three axes, a = 8.116(4) Å. In addition, single crystals of Ba2Ycu3O7–δ have been prepared from a KOH flux at 750 °C.

Crystal growth and scintillation properties of tube shape-controlled Ce-doped Y3Al5O12 single crystals grown by micro-pulling-down method

2020 ◽  
Vol 13 (12) ◽  
pp. 125503
Author(s):  
Atsushi Kotaki ◽  
Masao Yoshino ◽  
Yuui Yokota ◽  
Takashi Hanada ◽  
Akihiro Yamaji ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Single Crystals ◽  
Tube Shape ◽  
Shape Controlled

scholarly journals Single Crystal Growth and Physical Properties of Pyroxene CoGeO3

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 378
Author(s):  
Li Zhao ◽  
Zhiwei Hu ◽  
Hanjie Guo ◽  
Christoph Geibel ◽  
Hong-Ji Lin ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Crystal Growth ◽  
Physical Properties ◽  
Single Crystal ◽  
Single Crystals ◽  
Magnetic Moments ◽  
Single Crystal Growth ◽  
The Impact

We report on the synthesis and physical properties of cm-sized CoGeO3 single crystals grown in a high pressure mirror furnace at pressures of 80 bar. Direction dependent magnetic susceptibility measurements on our single crystals reveal highly anisotropic magnetic properties that we attribute to the impact of strong single ion anisotropy appearing in this system with TN∼33.5 K. Furthermore, we observe effective magnetic moments that are exceeding the spin only values of the Co ions, which reveals the presence of sizable orbital moments in CoGeO3.

Trends in Rare Earth Thiophosphate Syntheses: Rb3Ln(PS4)2 (Ln = La, Pr, Ce), Rb3-xNaxLn(PS4)2 (Ln = Pr, Ce; x = 0.50, 0.55), and RbEuPS4 Obtained by Molten Flux Crystal Growth

CrystEngComm ◽  
2021 ◽  
Author(s):  
Logan S Breton ◽  
Mark D. Smith ◽  
Hans-Conrad Zur Loye
Keyword(s):  
Rare Earth ◽  
Crystal Growth ◽  
Single Crystals ◽  
Molten Flux

Single crystals of new rubidium rare earth thiophosphates with the formulas Rb3Ln(PS4)2 (Ln = La, Pr, Ce), Rb3-xNaxLn(PS4)2 (Ln = Pr, Ce; x = 0.50, 0.55), and RbEuPS4 were crystallized...

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