Impurity content of synthetic quartz single crystals

1976 ◽  
Vol 36 (1) ◽  
pp. 188-190 ◽  
Author(s):  
Dipak Chakraborty
Keyword(s):  
Single Crystals ◽  
Impurity Content ◽  
Synthetic Quartz

Impurity content of synthetic quartz and its effect upon mechanical Q

1965 ◽  
Vol 3 (7) ◽  
pp. lxvi
Author(s):  
R.A. Laudise ◽  
A.A. Ballman ◽  
J.C. King
Keyword(s):  
Impurity Content ◽  
Synthetic Quartz

scholarly journals The critical shear stress of mercury single crystals

1937 ◽  
Vol 163 (912) ◽  
pp. 34-53 ◽  
Keyword(s):  
Plastic Deformation ◽  
Shear Stress ◽  
Melting Point ◽  
Single Crystal ◽  
Single Crystals ◽  
Critical Shear Stress ◽  
Impurity Content ◽  
Thermal Agitation ◽  
Plastic Yield ◽  
Metal Single Crystals

The influence of very small quantities of impurity on the critical shear stress of metal single crystals has an important bearing on the mechanism of their plastic deformation. For investigations in this field, mercury is a very suitable metal: its impurity content can easily be reduced to an extremely low level (Hulett 1911) and it contains no dissolved gases (Hulett 1911). Also, as first pointed out by Andrade (1914), single crystal wires of this metal can be prepared without difficulty. The low melting point of mercury (-38∙8° C.) is far from being a disadvantage. The crystals can be maintained at -60° C., and at a temperature so near the melting point the thermal agitation may be expected to accentuate phenomena not observable at lower temperatures, if such agitation plays the important part in the mechanism of glide ascribed to it (Taylor 1934; Polanyi 1934; Orowan 1934). As a possible instance of this, the experiments to be described have revealed the existence of a preliminary “set” preceding the true plastic yield. Widely differing forms of slip band have also been observed, and are described elsewhere (Greenland 1937). It is hoped that these results will throw further light on the mechanism of glide.

scholarly journals ELECTRON-PHONON COUPLING ORIGIN OF THE RESISTIVITY IN YNi2B2C SINGLE CRYSTALS

2000 ◽  
Vol 14 (25n27) ◽  
pp. 2840-2845 ◽  
Author(s):  
R. S. GONNELLI ◽  
A. MORELLO ◽  
G. A. UMMARINO ◽  
V. A. STEPANOV ◽  
G. BEHR ◽  
...  
Keyword(s):  
Single Crystals ◽  
Weighting Function ◽  
Impurity Content ◽  
Residual Resistivity ◽  
Approximation Formula ◽  
Tunneling Conductance ◽  
Phonon Coupling ◽  
S Wave ◽  
Eliashberg Equations ◽  
Electron Phonon Coupling

Resistivity measurements from 4.2 K up to 300 K were made on YNi 2 B 2 C single crystals with T c = 15.5 K . The resulting ρ(T) curve shows a perfect Bloch-Grüneisen (BG) behavior, with a very small residual resistivity which indicates the low impurity content and the high cristallographic quality of the samples. The value λ tr = 0.53 for the transport electron-phonon coupling constant was obtained by using the high-temperature constant value of d ρ/ d T and the plasma frequency reported in literature. The BG expression for the phononic part of the resistivity ρ ph (T) was then used to fit the data in the whole temperature range, by approximating [Formula: see text] with the experimental phonon spectral density G(Ω) multiplied by a two-step weighting function to be determined by the fit. The resulting fitting curve perfectly agrees with the experimental points. We also solved the real-axis Eliashberg equations in both s- and d-wave symmetries under the approximation [Formula: see text]. We found that the value of λ tr here determined in single-band approximation is quite compatible with T c and the gap Δ experimentally observed. Finally, we calculated the normalized tunneling conductance, whose comparison with break-junction tunnel data gives indication of the possible s-wave symmetry for the order parameter in YNi 2 B 2 C .

Plasticity of Single Crystals of Synthetic Quartz

2013 ◽  
pp. 29-53 ◽  
Author(s):  
B. E. Hobbs ◽  
A. C. McLaren ◽  
M. S. Paterson
Keyword(s):  
Single Crystals ◽  
Synthetic Quartz

Incorporation of impurities in tridymites from a used silica brick

1980 ◽  
Vol 43 (331) ◽  
pp. 879-883 ◽  
Author(s):  
H. Schneider ◽  
K. Wohlleben ◽  
A. Majdic
Keyword(s):  
High Resolution ◽  
Temperature Gradient ◽  
Single Crystals ◽  
Impurity Content ◽  
Material Transport ◽  
X Ray ◽  
Silica Brick ◽  
Cold Zone ◽  
Hot Zone ◽  
Main Impurity

SummaryThe incorporation of impurities in tridymites taken from a used silica brick have been studied by means of a high-resolution microprobe, X-ray fluorescence, X-ray diffractometry, and optical microscopy. The bulk impurity content of the brick changes strongly from the hot zone (4.7 wt%) to the colder part of the brick (7.6 wt%), indicating material transport along the temperature gradient. The transport medium for migration processes is probably a melt occurring in narrow veins between large tridymite crystals at high temperatures. The average impurity contents of homogeneous tridymite single crystals are 0.49 wt% in the hot zone of the brick and 0.81 wt% in the cold zone. Al2O3, TiO2, and Na2O are main impurity constituents; the tridymites do not contain significant amounts of Fe2O3 or CaO. The a parameters of tridymites decrease by about 0.26% from 4.9837 Å to 4.9709 Å from the hot zone to the cold zone of the brick and the c dimension shows a smaller decrease (0.11 %) from 8.2023 Å to 8.1933 Å.

THE INFLUENCE OF IMPURITIES ON THE MACROMOSAIC STRUCTURES OF TIN AND LEAD

1957 ◽  
Vol 35 (2) ◽  
pp. 208-215 ◽  
Author(s):  
H. A. Atwater ◽  
B. Chalmers
Keyword(s):  
Single Crystals ◽  
Impurity Content ◽  
Lattice Orientation ◽  
Direction Angle ◽  
Freezing Liquid ◽  
Influence Of Impurities

The properties and characteristics of arrays of low-angle boundaries which appear upon freezing of single crystals of tin and lead from the melt are shown to be dependent upon the amount and kind of impurities in the freezing liquid. The boundary-direction angle as a function of lattice orientation and impurity content in crystals frozen at speeds greater than 18–20 mm./minute is employed as an observational quantity. Measurements of boundary-direction are given for various impurity concentrations and types. Mechanisms for the determining of the boundary directions are proposed.

Influence of Impurities in SiC Powder on High Quality SiC Crystal Growth

2016 ◽  
Vol 858 ◽  
pp. 85-88
Author(s):  
S. Heo ◽  
H.R. Son ◽  
Byung Sook Kim ◽  
M.S. Kim ◽  
J.E. Han ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Single Crystals ◽  
Carbothermal Reduction ◽  
Impurity Content ◽  
The Other ◽  
High Quality ◽  
Other Hand ◽  
Traditional Process ◽  
Influence Of Impurities

SiC powders having different purities were prepared by carbothermal reduction under different conditions from traditional process and SiC single crystals were grown by the PVT method from the powders. After crystal growth, boule was cut to wafers and they were polished for chemical and defect analyses. Total impurities including Al, B and Ti which were derived from powders decreased remarkably during crystal growth. The formation of defects including micropipe and dislocations such as TED, TSD and BPD was strongly influenced by impurity content. The effect of impurity seemed to be negligible at below 1ppm level for MPD. On the other hand, dislocations continuously decreased even more when higher purity SiC powder below 1ppm level was used.

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