scholarly journals Bounds on the complex permittivity of polycrystalline materials by analytic continuation

2015 ◽  
Vol 471 (2174) ◽  
pp. 20140702 ◽  
Author(s):  
A. Gully ◽  
J. Lin ◽  
E. Cherkaev ◽  
K. M. Golden
Keyword(s):  
Sea Ice ◽  
Single Crystal ◽  
Analytic Continuation ◽  
Complex Permittivity ◽  
Crystal Orientation ◽  
Fluid Transport ◽  
Continuation Method ◽  
Growth Conditions ◽  
Polycrystalline Materials ◽  
Remote Sensing Techniques

An analytic continuation method for obtaining rigorous bounds on the effective complex permittivity ε * of polycrystalline composite materials is developed. It is assumed that the composite consists of many identical anisotropic crystals, each with a unique orientation. The key step in obtaining the bounds involves deriving an integral representation for ε *, which separates parameter information from geometrical information. Forward bounds are then found using knowledge of the single crystal permittivity tensor and mean crystal orientation. Inverse bounds are also developed, which recover information about the mean crystal orientation from ε *. We apply the polycrystalline bounds to sea ice, a critical component of the climate system. Different ice types, which result from different growth conditions, have different crystal orientation and size statistics. These characteristics significantly influence the fluid transport properties of sea ice, which control many geophysical and biogeochemical processes important to the climate and polar ecosystems. Using a two-scale homogenization scheme, where the single crystal tensor is numerically computed, forward bounds for sea ice are obtained and are in excellent agreement with columnar sea ice data. Furthermore, the inverse bounds are also applied to sea ice, helping to lay the groundwork for determining ice type using remote sensing techniques.

Effect of crystal orientation on droplet wetting behavior on single-crystal Al2O3 substrates: An experimental study

2020 ◽  
Vol 32 (12) ◽  
pp. 127110
Author(s):  
Chengyu He ◽  
Tie Liu ◽  
Lei Tian ◽  
Yubao Xiao ◽  
Shang Yuan ◽  
...  
Keyword(s):  
Experimental Study ◽  
Single Crystal ◽  
Crystal Orientation ◽  
Wetting Behavior

Confined orbitals in fullerenes and quantum dots calculated by analytic continuation method

2021 ◽  
Vol 75 (3) ◽  
Author(s):  
Milagros F. Morcillo-Arencibia ◽  
José Manuel Alcaraz-Pelegrina ◽  
Antonio J. Sarsa
Keyword(s):  
Quantum Dots ◽  
Analytic Continuation ◽  
Continuation Method

The effect of device geometry and crystal orientation on the stress-dependent offset voltage of 3C–SiC(100) four terminal devices

2015 ◽  
Vol 3 (34) ◽  
pp. 8804-8809 ◽  
Author(s):  
Afzaal Qamar ◽  
Hoang-Phuong Phan ◽  
Jisheng Han ◽  
Philip Tanner ◽  
Toan Dinh ◽  
...  
Keyword(s):  
Single Crystal ◽  
Crystal Orientation ◽  
Offset Voltage ◽  
Device Geometry ◽  
Stress Dependent ◽  
P Type ◽  
The Impact ◽  
First Time

This communication reports for the first time, the impact of device geometry on the stress-dependent offset voltage of single crystal p-type 3C–SiC four terminal devices.

Synchrotron white beam x-ray topography (SWBXT) and high resolution triple axis diffraction studies on AlN layers grown on 4H- and 6H-SiC seeds

2004 ◽  
Vol 831 ◽  
Author(s):  
Balaji Raghothamachar ◽  
Michael Dudley ◽  
Rafael Dalmau ◽  
Raoul Schlesser ◽  
Zlatko Sitar
Keyword(s):  
High Resolution ◽  
Single Crystal ◽  
Large Diameter ◽  
Laser Diodes ◽  
Growth Conditions ◽  
X Ray Diffraction ◽  
X Ray ◽  
White Beam ◽  
Strain Data ◽  
Growth Experiments

ABSTRACTFor nitride based devices such as LEDs, high power FETs and laser diodes, single crystal substrates of AlN are highly desirable. While the sublimation technique is suitable for growing bulk AlN crystals, appropriate seeds are also necessary for growing large diameter oriented boules. 4H- and 6H-SiC substrates which are readily available commercially can potentially be implemented as seeds for bulk AlN growth. However, issues regarding SiC decomposition at high temperatures, thermal expansion mismatch, single crystal growth, etc. need to be addressed. Towards this end, a series of growth experiments have been carried out in a resistively heated reactor using on and off-axis 4H- and 6H-SiC substrates as seeds for AlN growth from the vapor phase. Several hundred microns thick AlN layers have been grown under different growth conditions. Synchrotron white beam x-ray topography (SWBXT) has been used to map the defect distribution in the grown layers and high resolution triple axis x-ray diffraction (HRTXD) experiments were carried out to record reciprocal space maps from which tilt, mismatch and strain data can be obtained. These results are analyzed with respect to the growth conditions in order to gain a better understanding of this growth process.

scholarly journals Spatial Resolution in ACOM - What Will Come After EBSD

2008 ◽  
Vol 16 (1) ◽  
pp. 34-37 ◽  
Author(s):  
R.A. Schwarzer
Keyword(s):  
Grain Boundaries ◽  
Spatial Resolution ◽  
Crystal Orientation ◽  
High Sensitivity ◽  
Polycrystalline Materials ◽  
Phase Identification ◽  
Specific Level ◽  
Orientation Microscopy ◽  
Orientation Contrast ◽  
Phase Discrimination

Automated Crystal Orientation Microscopy (ACOM) on a grain specific level has proved to be an invaluable new tool for characterizing polycrystalline materials. It is usually based on scanning facilities using electron diffraction , due to its high sensitivity and spatial resolution, but also attempts have been made which rely upon X-ray or hard synchrotron radiation diffraction. The grain orientations are commonly mapped in pseudo-colors on the scanning grid to construct Crystal Orientation Maps (COM), which represent “images” of the microstructure with the advantage of providing quantitative orientation contrast. In a similar way, misorientations across grain boundaries, Σ values of grain boundaries, or other microstructural characteristics are visualized by mapping the grains in the micrograph with specific colors. The principal objectives are the determination of quantitative, statistically meaningful data sets of crystal orientations, misorientations, the CSL character (Σ) of grain boundaries, local crystal texture (pole figures, ODF, MODF, OCF) and derived entities, phase discrimination and phase identification.

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