EPR investigation of the structural perfection of Nd3+ doped YAG single crystals

1982 ◽  
Vol 36 (3) ◽  
pp. 348-350 ◽  
Author(s):  
�. P. Nikolova ◽  
B. L. Timan
Keyword(s):  
Single Crystals ◽  
Structural Perfection

Trends in the kinetic and magnetic properties of Pb0.8Sn0.2Te single crystals of high structural perfection

1999 ◽  
Vol 41 (10) ◽  
pp. 1604-1607 ◽  
Author(s):  
M. V. Radchenko ◽  
G. V. Lashkarev ◽  
E. I. Slyn’ko ◽  
A. P. Malysheva
Keyword(s):  
Magnetic Properties ◽  
Single Crystals ◽  
Structural Perfection ◽  
High Structural Perfection

scholarly journals Dynamical X-ray diffraction imaging of voids in dislocation-free high-purity germanium single crystals

2020 ◽  
Vol 53 (4) ◽  
pp. 880-884 ◽  
Author(s):  
Kevin-P. Gradwohl ◽  
Andreas N. Danilewsky ◽  
Melissa Roder ◽  
Martin Schmidbauer ◽  
József Janicskó-Csáthy ◽  
...  
Keyword(s):  
Single Crystals ◽  
High Purity ◽  
Direct Evidence ◽  
X Ray Diffraction ◽  
Structural Perfection ◽  
X Ray ◽  
High Purity Germanium ◽  
High Structural Perfection ◽  
Diffraction Imaging ◽  
General Method

White-beam X-ray topography has been performed to provide direct evidence of micro-voids in dislocation-free high-purity germanium single crystals. The voids are visible because of a dynamical diffraction contrast. It is shown that voids occur only in dislocation-free parts of the crystal and do not show up in regions with homogeneous and moderate dislocation density. It is further suggested that the voids originate from clustering of vacancies during the growth process. A general method is proposed to verify the presence of voids for any crystalline material of high structural perfection.

Enhancement of structural perfection of alkali halide single crystals by doping with copper

2012 ◽  
Vol 353 (1) ◽  
pp. 95-100 ◽  
Author(s):  
D. Joseph Daniel ◽  
P. Ramasamy ◽  
U. Madhusoodanan ◽  
G. Bhagavannarayana
Keyword(s):  
Single Crystals ◽  
Alkali Halide ◽  
Structural Perfection

A study of the effect of annealing on Fe-doped LiNbO3by HRXRD, XRT and FT–IR

2005 ◽  
Vol 38 (5) ◽  
pp. 768-771 ◽  
Author(s):  
G. Bhagavannarayana ◽  
R. V. Ananthamurthy ◽  
G. C. Budakoti ◽  
B. Kumar ◽  
K. S. Bartwal
Keyword(s):  
Fourier Transform ◽  
Grain Boundaries ◽  
Single Crystals ◽  
Elevated Temperatures ◽  
Annealing Effect ◽  
Molar Ratio ◽  
Structural Perfection ◽  
X Ray ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

The annealing effect on the structural perfection of Fe-doped LiNbO3single crystals has been studied by high-resolution X-ray diffractometry (HRXRD), X-ray topography (XRT) and Fourier transform infrared (FT–IR) spectroscopy. The single crystals, prepared by mixing Li2CO3and Nb2O5powders in the molar ratio 48.6:51.4 with 0.05 mol% of iron at 1415 (1) K, were grown by the Czochralski (CZ) method along the [001] direction in air and poled during crystal growth by the application of a DC field. Two low-angle (tilt angle ∼1 arc minute) structural grain boundaries were observed in as-grown specimens. FT–IR spectra revealed that these crystals contain OH−and CO32−ionic defects. Grain boundaries and CO32−ionic defects were successfully removed, while the concentration of OH−ions was considerably reduced by post-growth thermal annealing at elevated temperatures.

X-Ray Topography Study of the Nickel Superalloy CMSX-4 Single Crystals

2010 ◽  
Vol 163 ◽  
pp. 260-263 ◽  
Author(s):  
Arkadiusz Onyszko ◽  
Włodzimierz Bogdanowicz ◽  
Krzysztof Kubiak ◽  
Jan Sieniawski
Keyword(s):  
Single Crystals ◽  
Turbine Blades ◽  
Nickel Superalloy ◽  
Bridgman Method ◽  
Nickel Superalloys ◽  
Structural Perfection ◽  
X Ray

The paper attempts to determine structural perfection of monocrystalline nickel superalloys using X-ray topography. Monocrystalline bars and turbine blades were manufactured in an ALD Vacuum Technologies furnace using the Bridgman method. Pulling out rates typical for CMSX-4 nickel superalloys were used. It has been found that in the case of monocrystalline bars the structural perfection determined based on X-ray topograms does not depend on the distance from the selector. Instead, for blades the structural perfection significantly decreases with increasing distance from the selector.

Favourable growth conditions for the preparation of bulk AlN single crystals by PVT

CrystEngComm ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1762-1768 ◽  
Author(s):  
C. Hartmann ◽  
L. Matiwe ◽  
J. Wollweber ◽  
I. Gamov ◽  
K. Irmscher ◽  
...  
Keyword(s):  
Growth Rate ◽  
Single Crystals ◽  
Growth Conditions ◽  
Structural Perfection ◽  
High Structural Perfection ◽  
Deep Uv

A high seed temperature (2251 °C) reveals the highest deep UV transparency (α265nm = 27 cm−1), a high structural perfection (EPD = 9 × 103 cm−2) and a suitable growth rate (R = 200 μm h−1).

Investigation of the Influence of Structural Defects on the PL Spectra in n-3C-SiC

2020 ◽  
Vol 1004 ◽  
pp. 278-283
Author(s):  
Lev V. Shakhov ◽  
Alexander A. Lebedev ◽  
Natalia. V. Seredova ◽  
Sergey P. Lebedev ◽  
Vitalii V. Kozlovski ◽  
...  
Keyword(s):  
Single Crystals ◽  
Structural Defects ◽  
Epitaxial Layers ◽  
Radiation Defects ◽  
Photoluminescence Spectra ◽  
Structural Perfection ◽  
Twin Boundaries ◽  
Pl Spectra ◽  
Donor Acceptor

The photoluminescence spectra were studied in 3C-SiC / 4H-SiC heterostructures and single crystals of 3C-SiC. It was shown that 3C-SiC epitaxial layers grown on 4H-SiC substrates have significantly less structural perfection than 3C-SiC single crystals. It was found that doping with aluminum leads to the appearance of characteristic photoluminescence (PL) both in the epitaxial layers and in 3C-SiC single crystals. At the same time, the irradiation of the epitaxial layers does not lead to the appearance of “defective PL (DFL), as is observed for single crystals. It was suggested that the twin boundaries existing in 3C-SiC epitaxial layers could serve as getters of radiation defects that are components of donor – acceptor pairs (DAP) responsible for DFL.

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