Superradiance of High Density Frenkel Excitons at Room Temperature

1995 ◽  
Vol 74 (20) ◽  
pp. 4079-4082 ◽  
Author(s):  
H. Z. Wang ◽  
X. G. Zheng ◽  
F. L. Zhao ◽  
Z. L. Gao ◽  
Z. X. Yu
Keyword(s):  
Room Temperature ◽  
High Density ◽  
Frenkel Excitons

scholarly journals Experimental and Numerical Investigation of the ECAP Processed Copper: Microstructural Evolution, Crystallographic Texture and Hardness Homogeneity

Metals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 607
Author(s):  
A. I. Alateyah ◽  
Mohamed M. Z. Ahmed ◽  
Yasser Zedan ◽  
H. Abd El-Hafez ◽  
Majed O. Alawad ◽  
...  
Keyword(s):  
Grain Size ◽  
Equal Channel Angular Pressing ◽  
Cross Section ◽  
Room Temperature ◽  
Pure Copper ◽  
High Density ◽  
Ecap Processing ◽  
Heterogeneous Distribution ◽  
Angular Pressing ◽  
Average Grain Size

The current study presents a detailed investigation for the equal channel angular pressing of pure copper through two regimes. The first was equal channel angular pressing (ECAP) processing at room temperature and the second was ECAP processing at 200 °C for up to 4-passes of route Bc. The grain structure and texture was investigated using electron back scattering diffraction (EBSD) across the whole sample cross-section and also the hardness and the tensile properties. The microstructure obtained after 1-pass at room temperature revealed finer equiaxed grains of about 3.89 µm down to submicrons with a high density of twin compared to the starting material. Additionally, a notable increase in the low angle grain boundaries (LAGBs) density was observed. This microstructure was found to be homogenous through the sample cross section. Further straining up to 2-passes showed a significant reduction of the average grain size to 2.97 µm with observable heterogeneous distribution of grains size. On the other hand, increasing the strain up to 4-passes enhanced the homogeneity of grain size distribution. The texture after 4-passes resembled the simple shear texture with about 7 times random. Conducting the ECAP processing at 200 °C resulted in a severely deformed microstructure with the highest fraction of submicron grains and high density of substructures was also observed. ECAP processing through 4-passes at room temperature experienced a significant increase in both hardness and tensile strength up to 180% and 124%, respectively.

Development of Toughened, Fine Grained, Recrystallized W-1.1%TiC

2021 ◽  
Vol 1024 ◽  
pp. 103-109
Author(s):  
Shunsuke Makimura ◽  
Hiroaki Kurishita ◽  
Koichi Niikura ◽  
Hun Chea Jung ◽  
Hiroyuki Ishizaki ◽  
...  
Keyword(s):  
Melting Point ◽  
Low Temperature ◽  
Fracture Strength ◽  
Room Temperature ◽  
Target Material ◽  
High Density ◽  
High Melting ◽  
High Melting Point ◽  
Irradiation Embrittlement ◽  
Fine Grained

Tungsten (W) is a principal candidate as target material because of its high density and extremely high melting point. W inherently has a critical disadvantage of its brittleness at around room temperature (low temperature brittleness), recrystallization embrittlement, and irradiation embrittlement. TFGR (Toughened, Fine Grained, Recrystallized) W-1.1%TiC has been considered as a realized solution to the embrittlement problems. We started to fabricate TFGR W-1.1%TiC in 2016 under collaboration between KEK and Metal Technology Co. LTD (MTC). The TFGR W-1.1%TiC samples were successfully fabricated in June, 2018. As a result, the specimen showed slight bend ductility and 2.6 GPa of fracture strength.

Effect of Electron Scavenger on the γ-Radiolysis of Gaseous Propane at High Densities

1973 ◽  
Vol 51 (23) ◽  
pp. 3966-3969 ◽  
Author(s):  
Masaru Nishikawa ◽  
Yoh-ichi Yamaguchi ◽  
Kazuo Fujita ◽  
Kazunori Kon ◽  
Tetsuro Okamoto
Keyword(s):  
Liquid Phase ◽  
Room Temperature ◽  
High Density ◽  
Hydrogen Formation ◽  
Electron Pairs ◽  
Electron Scavenger ◽  
Similar Decrease

Hydrogen formation from γ-radiolysis of gaseous propane at 120 ± 1 °C was studied as the function of density in the range from 0.1 to 0.5 g/ml. G(H2) gradually decreased with density from 8.0 at 0.12 g/ml towards the liquid-phase value of 6.4 at room temperature. G(H2) in the presence of SF6 showed similar decrease from 3.9 to 3.0. The decrease was discussed in comparison to the abrupt drop in G-values from the radiolysis of ammonia at high density (11). The separation distances of ion–electron pairs were estimated from the analysis of the electron scavenging reaction.

Synthesis and Magnetic Properties of Co Nanorod Superlattices

2006 ◽  
Vol 962 ◽  
Author(s):  
Fabienne Wetz ◽  
Katerina Soulantica ◽  
Marc Respaud ◽  
Andrea Falqui ◽  
Bruno Chaudret
Keyword(s):  
Thermal Decomposition ◽  
Magnetic Properties ◽  
Magnetic Anisotropy ◽  
Magnetic Recording ◽  
Coercive Field ◽  
Shape Control ◽  
Room Temperature ◽  
High Density ◽  
High Density Magnetic Recording ◽  
Long Chain

ABSTRACTWe present the synthesis and magnetic properties of Co nanorods spontaneously organized in superlattices over a surface of several microns. This material results from the thermal decomposition of a cobalt precursor under hydrogen, in the presence of a long-chain amine and a long-chain acid as shape control agents. These nanorod superlattices are ferromagnetic at room temperature and they are characterized by a strong coercive field as a consequence of their large magnetic anisotropy. This system can be considered as a good candidate for high density magnetic recording.

Origin of Voids at the Interface of Wafer Bonded Sapphire on Sapphire

2000 ◽  
Vol 654 ◽  
Author(s):  
Stephan Senz ◽  
Pascal Kopperschmidt ◽  
Nikolai Dimitri Zakharov
Keyword(s):  
Free Volume ◽  
Cross Section ◽  
Bonding Strength ◽  
Room Temperature ◽  
High Density ◽  
Bonding Energy ◽  
Plan View ◽  
Bonded Interface ◽  
Heating Up

AbstractTwo sapphire (Al2O3, r-cut) wafers were bonded at room temperature. The bonding energy increased during heating up to 1100 °C. The interface was investigated by plan-view and cross-section TEM. The bonding strength after heating to 1100 °C is similar to the bulk bonding strength. A high density of voids at the bonded interface was observed. The voids are elongated along the interface in a pancake shape. The surfaces are low index planes. The volume inside the voids is higher than expected from a model, where a hydrophobic initial bonding is assumed. The strength of initial bonding and the free volume at the interface can be understood, if the sapphire surfaces are hydrophilic and covered by several monolayers of water during initial bonding. During annealing the water diffuses out along the bonded interface and a free volume remains.

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