Dependence of Scintillators Optical Properties on Intrinsic Structural Defects

1994 ◽  
Vol 348 ◽  
Author(s):  
N.V. Kilassen
Keyword(s):  
Plastic Deformation ◽  
Optical Properties ◽  
Crystal Growth ◽  
Spectral Distribution ◽  
Light Output ◽  
Structural Defects ◽  
High Quality ◽  
Intrinsic Defects ◽  
Distribution Kinetics ◽  
Wide Range

ABSTRACTThe studies of the dependence of the optical properties of various scintillators on intrinsic structural defects have been reviewed. The greater part of the review is devoted to the defects introduced by plastic deformation. A wide range of variations in the light output, spectral distribution, kinetics and other properties has been observed. These defects can be induced during crystal growth, annealing, processing, etc. The proper regulation of the superstructure of intrinsic defects can ensure the production of high quality scintillators having required properties.

scholarly journals Single crystal growth of bulk InGaZnO4 and analysis of its intrinsic transport properties

CrystEngComm ◽  
2019 ◽  
Vol 21 (19) ◽  
pp. 2985-2993 ◽  
Author(s):  
Yusuke Tanaka ◽  
Kazuhiro Wada ◽  
Yuki Kobayashi ◽  
Takenori Fujii ◽  
Saleem J. Denholme ◽  
...  
Keyword(s):  
High Pressure ◽  
Optical Properties ◽  
Crystal Growth ◽  
Single Crystals ◽  
Single Crystal Growth ◽  
Floating Zone ◽  
Zone Method ◽  
High Quality ◽  
Electrical And Optical Properties ◽  
Floating Zone Method

Large, high-quality InGaZnO4 single crystals grown by high-pressure optical floating zone method and its electrical and optical properties.

scholarly journals Photoluminescence and structural defects of ZnO films deposited by reactive magnetron sputtering with unconventional Ar-O2 gas mixture formation

2021 ◽  
Author(s):  
Kristina Bockute ◽  
Keyword(s):  
Magnetron Sputtering ◽  
Band Gap ◽  
Reactive Magnetron Sputtering ◽  
Structural Defects ◽  
Zno Films ◽  
Composition Analysis ◽  
Gas Mixture ◽  
Reactive Magnetron ◽  
Intrinsic Defects ◽  
Wide Range

ZnO is a well-known traditional industrial material which has high potential to become one of the key components for the next generation of future electronics, LED emitters, visible light photocatalysis and others. In its pristine form ZnO has relatively wide band gap of approximately 3.4 eV, but a lot of emerging applications requires some level of electronic structure engineering and structure optimisation. Studies show that ZnO properties strongly depend on the intrinsic defects type and concentrations. Both characteristics usually are depending on the synthesis method. Accordingly, there is great interest to develop new methods which would allow to obtain ZnO with optimised band gap and other properties. In current, study ZnO films were deposited using reactive magnetron sputtering with unconventional Ar-O2 gas mixture supply control: Ar flow was controlled to maintain total gas pressure at 1x10-2 mbar, whereas O2 flow rate was actively adjusted to maintain the selected intensity of optical zinc emission from the working cathode zone. Applying such ZnO formation method it was possible to stabilise reactive magnetron sputtering process over wide range of conditions. Elemental composition analysis by XPS revealed that despite large variations in Zn emission peak intensity within tested experimental conditions all films had nearly identical Zn:O ratios but at the same time their structural and optical properties differed significantly. The colour of the films varied from highly transparent yellowish-greenish, to intense orange, to opaque black. XRD analysis showed that films consisted of single polycrystalline wurtzite phase with varying orientations. PL spectroscopy analysis revealed that films had a lot of various defects including oxygen and zinc vacancies, interstitials and surface defects. Wide variation of ZnO properties obtained by different reactive sputtering conditions demonstrates the potential of the proposed method to control the formation of various intrinsic defects and to tailor their concentration.

Optical Properties of HVEM Accelerators

1975 ◽  
Vol 33 ◽  
pp. 180-181
Author(s):  
A. Strojnik ◽  
J.W. Scholl ◽  
V. Bevc
Keyword(s):  
Optical Properties ◽  
Electron Accelerator ◽  
Systematic Investigation ◽  
Electron Source ◽  
High Brightness ◽  
The Past ◽  
Wide Range ◽  
Optical Behavior

The electron accelerator, as inserted between the electron source (injector) and the imaging column of the HVEM, is usually a strong lens and should be optimized in order to ensure high brightness over a wide range of accelerating voltages and illuminating conditions. This is especially true in the case of the STEM where the brightness directly determines the highest resolution attainable. In the past, the optical behavior of accelerators was usually determined for a particular configuration. During the development of the accelerator for the Arizona 1 MEV STEM, systematic investigation was made of the major optical properties for a variety of electrode configurations, number of stages N, accelerating voltages, 1 and 10 MEV, and a range of injection voltages ϕ0 = 1, 3, 10, 30, 100, 300 kV).

Ab initio calculation on the Optical Properties of AA- Stacked two dimensional Graphene, Silicene, Germanene, and Stanene

2018 ◽  
Vol 1 (1) ◽  
pp. 46-50
Author(s):  
Rita John ◽  
Benita Merlin
Keyword(s):  
Optical Properties ◽  
Band Structure ◽  
Density Functional ◽  
Electronic Band Structure ◽  
Complex Refractive Index ◽  
Single Layer ◽  
Generalized Gradient ◽  
Electronic Band ◽  
Wide Range ◽  
Optical Region

In this study, we have analyzed the electronic band structure and optical properties of AA-stacked bilayer graphene and its 2D analogues and compared the results with single layers. The calculations have been done using Density Functional Theory with Generalized Gradient Approximation as exchange correlation potential as in CASTEP. The study on electronic band structure shows the splitting of valence and conduction bands. A band gap of 0.342eV in graphene and an infinitesimally small gap in other 2D materials are generated. Similar to a single layer, AA-stacked bilayer materials also exhibit excellent optical properties throughout the optical region from infrared to ultraviolet. Optical properties are studied along both parallel (||) and perpendicular ( ) polarization directions. The complex dielectric function (ε) and the complex refractive index (N) are calculated. The calculated values of ε and N enable us to analyze optical absorption, reflectivity, conductivity, and the electron loss function. Inferences from the study of optical properties are presented. In general the optical properties are found to be enhanced compared to its corresponding single layer. The further study brings out greater inferences towards their direct application in the optical industry through a wide range of the optical spectrum.

AMPCOLOY 570

Alloy Digest ◽  
1980 ◽  
Vol 29 (3) ◽  
Keyword(s):  
Corrosion Resistance ◽  
Cast Iron ◽  
Iron Alloy ◽  
Heat Treating ◽  
Nickel Aluminum ◽  
High Quality ◽  
Glass Making ◽  
Temperature Performance ◽  
Wide Range ◽  
Cobalt Iron

Abstract AMPCOLOY 570 is a cast copper-nickel-aluminum-cobalt-iron alloy specially developed for applications involving severe stresses and high temperatures, such as glass-making molds and plate-glass rolls. It is significantly superior to cast iron which has been commonly used for glass-making molds. Good foundry techniques will yield high-quality castings of Ampcoloy 570 in a wide range of section sizes. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on high temperature performance and corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Cu-392. Producer or source: Ampco Metal Inc..

Carbon Dots for Bacterial Detection and Antibacterial Applications-A Minireview

2020 ◽  
Vol 25 (46) ◽  
pp. 4848-4860 ◽  
Author(s):  
Anisha Anand ◽  
Gopinathan Manavalan ◽  
Ranju Prasad Mandal ◽  
Huan-Tsung Chang ◽  
Yi-Ru Chiou ◽  
...  
Keyword(s):  
Optical Properties ◽  
Carbon Dots ◽  
Antibacterial Effect ◽  
Bacterial Detection ◽  
High Brightness ◽  
Photo Catalysis ◽  
Wide Range ◽  
Prevention And Treatment ◽  
Low Toxicity ◽  
Conventional Antibiotics

: The prevention and treatment of various infections caused by microbes through antibiotics are becoming less effective due to antimicrobial resistance. Researches are focused on antimicrobial nanomaterials to inhibit bacterial growth and destroy the cells, to replace conventional antibiotics. Recently, carbon dots (C-Dots) become attractive candidates for a wide range of applications, including the detection and treatment of pathogens. In addition to low toxicity, ease of synthesis and functionalization, and high biocompatibility, C-Dots show excellent optical properties such as multi-emission, high brightness, and photostability. C-Dots have shown great potential in various fields, such as biosensing, nanomedicine, photo-catalysis, and bioimaging. This review focuses on the origin and synthesis of various C-Dots with special emphasis on bacterial detection, the antibacterial effect of CDots, and their mechanism.

Sector growth and symmetry of (F,OH) apatite from the Asio mine, Japan

1994 ◽  
Vol 58 (391) ◽  
pp. 307-314 ◽  
Author(s):  
Mizuhiko Akizuki ◽  
Hirotugu Nisidoh ◽  
Yasuhiro Kudoh ◽  
Tomohiro Watanabe ◽  
Kazuo Kurata
Keyword(s):  
Optical Properties ◽  
Crystal Growth ◽  
Electron Diffraction ◽  
Chemical Analysis ◽  
Growth Surface ◽  
Complete Disappearance ◽  
X Ray ◽  
Solid Crystal ◽  
Wet Chemical ◽  
Growth Features

AbstractA study of apatite crystals from the Asio mine, Japan, showed sectoral texture related to the growth of the crystal, and with optically biaxial properties within the sectors. Wet chemical analysis gave a composition Ca5(PO4)3(F0.64,OH0.38,Cl0.01)1.03 for the specimen.Additional diffraction spots were not observed in precession and oscillation X-ray photographs and electron diffraction photographs. Since the internal textures correlate with the surface growth features, it is suggested that the internal textures and the unusual optical properties were produced during nonequilibrium crystal growth. The fluorine/hydroxyl sites in hexagonal apatite are symmetrically equivalent in the solid crystal but, at a growth surface, this equivalence may be lost, resulting in a reduction of crystal symmetry. Heating of the apatite to about 850°C results in the almost complete disappearance of the optical anomalies due to disordering, which may be related to the loss of hydroxyl from the crystal.

Microstructural and optical properties of high-quality Mg–Zn oxide thin films

2021 ◽  
Vol 127 ◽  
pp. 105690
Author(s):  
A. Sáenz-Trevizo ◽  
D. Kuchle-Mena ◽  
P. Pizá-Ruiz ◽  
P. Amézaga-Madrid ◽  
O. Solís-Canto ◽  
...  
Keyword(s):  
Thin Films ◽  
Optical Properties ◽  
Oxide Thin Films ◽  
High Quality

scholarly journals Novel Cs2HfCl6 Crystal Scintillator: Recent Progress and Perspectives

Physics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 320-351
Author(s):  
Serge Nagorny
Keyword(s):  
Recent Progress ◽  
Raw Materials ◽  
Light Output ◽  
Light Yield ◽  
Thermal Conditions ◽  
Pulse Shape Discrimination ◽  
Main Element ◽  
High Quality ◽  
Crystal Sample ◽  
Discrimination Ability

Recent progress in Cs2HfCl6 (CHC) crystal production achieved within the last five years is presented. Various aspects have been analyzed, including the chemical purity of raw materials, purification methods, optimization of the growth and thermal conditions, crystal characterization, defect structure, and internal radioactive background. Large volume, crack-free, and high quality CHC crystals with an ultimate scintillating performance were produced as a result of such extensive research and development (R & D) program. For example, the CHC crystal sample with dimensions ∅23 × 30 mm3 demonstrates energy resolution of 3.2% FWHM at 662 keV, the relative light output at the level of 30,000 ph/MeV and excellent linearity down to 20 keV. Additionally, this material exhibits excellent pulse shape discrimination ability and low internal background of less than 1 Bq/kg. Furthermore, attempts to produce a high quality CHC crystal resulted in research on this material optimization by constitution of either alkali ions (Cs to Tl), or main element (Hf to Zr), or halogen ions (Cl to Br, I, or their mixture in different ratio), as well as doping with various active ions (Te4+, Ce3+, Eu3+, etc.). This leads to a range of new established scintillating materials, such as Tl2HfCl6, Tl2ZrCl6, Cs2HfCl4Br2, Cs2HfCl3Br3, Cs2ZrCl6, and Cs2HfI6. To exploit the whole potential of these compounds, detailed studies of the material’s fundamental properties, and understanding of the variety of the luminescence mechanisms are required. This will help to understand the origin of the high light yield and possible paths to further extend it. Perspectives of CHC crystals and related materials as detectors for rare nuclear processes are also discussed.

scholarly journals Formation of Carbon Quantum Dots via Hydrothermal Carbonization: Investigate the Effect of Precursors

Energies ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 986
Author(s):  
Md Rifat Hasan ◽  
Nepu Saha ◽  
Thomas Quaid ◽  
M. Toufiq Reza
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Microcrystalline Cellulose ◽  
Uv Light ◽  
Synthesis Method ◽  
Hydrothermal Carbonization ◽  
Carbon Quantum Dots ◽  
Medical Diagnostics ◽  
Particle Size Range ◽  
Wide Range

Carbon quantum dots (CQDs) are nanomaterials with a particle size range of 2 to 10 nm. CQDs have a wide range of applications such as medical diagnostics, bio-imaging, biosensors, coatings, solar cells, and photocatalysis. Although the effect of various experimental parameters, such as the synthesis method, reaction time, etc., have been investigated, the effect of different feedstocks on CQDs has not been studied yet. In this study, CQDs were synthesized from hydroxymethylfurfural, furfural, and microcrystalline cellulose via hydrothermal carbonization at 220 °C for 30 min of residence time. The produced CQDs showed green luminescence behavior under the short-wavelength UV light. Furthermore, the optical properties of CQDs were investigated using ultraviolet-visible spectroscopy and emission spectrophotometer, while the morphology and chemical bonds of CQDs were investigated using transmission electron microscopy and Fourier-transform infrared spectroscopy, respectively. Results showed that all CQDs produced from various precursors have absorption and emission properties but these optical properties are highly dependent on the type of precursor. For instance, the mean particle sizes were 6.36 ± 0.54, 5.35 ± 0.56, and 3.94 ± 0.60 nm for the synthesized CQDs from microcrystalline cellulose, hydroxymethylfurfural, and furfural, respectively, which appeared to have similar trends in emission intensities. In addition, the synthesized CQDs experienced different functionality (e.g., C=O, O-H, C-O) resulting in different absorption behavior.

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