scholarly journals Crystal imperfections in ice Ih

2020 ◽  
Vol 153 (11) ◽  
pp. 110902 ◽  
Author(s):  
Maurice de Koning
Keyword(s):  
Crystal Imperfections

The absorption spectra of irradiated diamonds after heat treatment

1956 ◽  
Vol 237 (1208) ◽  
pp. 75-89 ◽  
Keyword(s):  
Absorption Spectra ◽  
Absorption Lines ◽  
Type I ◽  
Type Ii ◽  
Large Reduction ◽  
Isothermal Heating ◽  
Interstitial Carbon ◽  
Crystal Imperfections ◽  
Continuous Absorption ◽  
Kinetics Of

The absorption spectra of eight type I and three type II a diamonds irradiated with neutrons, electrons or y-rays have been recorded at 80 and 290°K after various heat treatments in the temperature range 0 to 900°C. It is found that heating in the range 350 to 450°C causes a general reduction in the irradiation-induced absorption owing to the recombination of those interstitials and vacancies which are near neighbours. Heating type II a diamonds at 600°C causes a large reduction in the irradiation-induced lines and new lines appear. These are probably due to pairs of identical defects, and the kinetics of their formation during isothermal heating at 600°C are presented. At higher temperatures all absorption lines in type II a diamonds disappear and only continuous absorption remains. This is probably due to amorphous or graphitic regions produced by agglomeration of defects. Type I diamonds show the same kind of absorption, but in addition show an increase in strength of the natural lines and also some new absorption lines which are not removed by heating at 900°C. It is suggested that these additional processes are due to the anchoring of vacant atomic sites and interstitial carbon atoms at crystal imperfections present only in type I diamonds.

Influence of Micropipe and Domain Boundary in SiC Substrate on the DC Characteristics of AlGaN/GaN HFET

2007 ◽  
Vol 556-557 ◽  
pp. 1043-1046 ◽  
Author(s):  
Hiroyuki Sazawa ◽  
Tomohisa Kato ◽  
Kazutoshi Kojima ◽  
K. Furuta ◽  
K. Hirata ◽  
...  
Keyword(s):  
Domain Boundary ◽  
Topographic Analysis ◽  
Raman Analysis ◽  
X Ray ◽  
Free Carriers ◽  
Crystal Imperfections ◽  
Dc Characteristics ◽  
Domain Boundaries ◽  
Gan Hfet ◽  
Gan Crystal

AlGaN/GaN HFETs were fabricated around micropipes and on a domain boundary in a semi-insulating silicon carbide (SI-SiC) substrate and the DC characteristics of the fabricated devices were measured. Devices around micropipe showed no pinch-off or large gate leakage. The devices on the domain boundaries showed no degradation in the performances, even though an X-ray topographic analysis indicated that crystal imperfections, due to the defects, propagated to the GaN layer across the hetero interface. Based on these results, we concluded that micropipe degrades the DC characteristics and that the domain boundary does not affect the DC characteristics. From Raman analysis on the devices around the micropipes, these degradations could be attributed to the free carriers introduced into the GaN crystal by the micropipes.

scholarly journals Matching X-ray beam and detector properties to protein crystals of different perfection

2014 ◽  
Vol 21 (3) ◽  
pp. 537-546 ◽  
Author(s):  
Colin Nave
Keyword(s):  
Data Processing ◽  
Room Temperature ◽  
Angular Resolution ◽  
Block Size ◽  
Quality Parameters ◽  
Mosaic Block ◽  
X Ray ◽  
Crystal Imperfections ◽  
Crystal Strain ◽  
Set Up

An analysis is given of the effect of different beam and detector parameters on the sharpness of recorded diffraction features for macromolecular crystals of different quality. The crystal quality parameters include crystal strain, crystal or mosaic block size and mosaic block misorientation. Calculations are given for instrument parameters such as angular resolution of the detector, beam divergence and wavelength bandpass to be matched to the intrinsic diffraction properties from these crystals with the aim of obtaining the best possible data out of each crystal. Examples are given using typical crystal imperfections obtained from the literature for both room-temperature and cryo-cooled crystals. Possible implications for the choice of X-ray source, beamline design, detector specifications, instrument set-up and data processing are discussed, together with the limitations of the approach.

scholarly journals Boosting the thermoelectric performance of p-type heavily Cu-doped polycrystalline SnSe via inducing intensive crystal imperfections and defect phonon scattering

2018 ◽  
Vol 9 (37) ◽  
pp. 7376-7389 ◽  
Author(s):  
Xiaolei Shi ◽  
Kun Zheng ◽  
Min Hong ◽  
Weidi Liu ◽  
Raza Moshwan ◽  
...  
Keyword(s):  
Single Crystal ◽  
Phonon Scattering ◽  
Thermoelectric Performance ◽  
Solvothermal Route ◽  
Crystal Imperfections ◽  
P Type ◽  
First Time

In this study, we, for the first time, report a high Cu solubility of 11.8% in single crystal SnSe microbelts synthesized via a facile solvothermal route.

The X-Ray Investigation of Preprecipitation in Supersaturated Solid Solutions

1962 ◽  
Vol 6 ◽  
pp. 25-42 ◽  
Author(s):  
A. Lutts
Keyword(s):  
Diffuse Scattering ◽  
Physical And Mechanical Properties ◽  
Age Hardening ◽  
Precipitation Process ◽  
X Rays ◽  
Paper Briefly ◽  
Crystal Imperfections ◽  
Supersaturated Solid Solutions ◽  
Aging Stage ◽  
Supersaturated Solutions

AbstractThis paper briefly traces the study of the preprecipitation or cold-aging stage of the decomposition of supersaturated solutions by means of diffuse scattering of X-rays.This part of the overall precipitation process is of considerable practical as well as theoretical interest because it is during preprecipitation that changes in many physical and mechanical properties take place without the formation of a precipitate phase.Examples will be given to show the types of zones encountered during this stage in various age-hardening alloys. These will attempt to illustrate the contribution which the study of diffuse scattering of X-rays, guided by present-day concepts of crystal imperfections, has made toward a better understanding of the precipitation process in alloys.

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