Excitation and Relaxation Processes of Impact Excitation Emission of Er3+ Ions in InP

1993 ◽  
Vol 301 ◽  
Author(s):  
T. Kimura ◽  
H. Ishida ◽  
S. Yugo ◽  
R. Saito ◽  
H. Isshiki ◽  
...  
Keyword(s):  
Thermal Quenching ◽  
Decay Process ◽  
Impact Excitation ◽  
Relaxation Processes ◽  
Measured Temperature ◽  
Time Decay ◽  
Time Resolved ◽  
Measured Temperature Range ◽  
Temperature Range ◽  
The Impact

ABSTRACTTime-resolved excitation and relaxation processes of the impact excitation emission (EL) at 1.54μm of Er3+ ions doped in InP were investigated in the temperature range from 77K to 330K. The decay process was almost exponential in all the measured temperature range and showed little thermal quenching. The decay time of 2ms at 77K decreased only to tms at 330K. This result contrasted with the large thermal quenching and nonexponential characteristics of the photoluminescence (PL) time decay at higher temperatures, suggesting different Er3+ centers excited between EL and PL. A two-emission-center model is proposed and the different behaviors of thermal quenching and time decay between EL and PL emissions are consistently explained.

Thermoelectric Properties of Doped Iron Disilicide

2000 ◽  
Vol 626 ◽  
Author(s):  
Jun-ichi Tani ◽  
Hiroyasu Kido
Keyword(s):  
Thermal Conductivity ◽  
Electrical Resistivity ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Measured Temperature ◽  
Iron Disilicide ◽  
Measured Temperature Range ◽  
Temperature Range

ABSTRACTIn order to investigate the thermoelectric properties of Re-doped β-FeSi2 (Fe1-xRexSi2), Ir-doped β-FeSi2 (Fe1-xIrxSi2), and Pt-doped β-FeSi2 (Fe1-xPtxSi2), the electrical resistivity, the Seebeck coefficient, and the thermal conductivity of these samples have been measured in the temperature range between 300 and 1150 K. Fe1-xRexSi2 is p-type, while Fe1-xIrxSi2 and Fe1-xPt xSi2 are n-type over the measured temperature range. The solubility limits of dopant are estimated to be 0.2at% for Fe1-xRexSi2, 0.5at% for Fe1-xIrxSi2, and 1.9at% for Fe1-xPtxSi2. A maximum ZT value of 0.14 was obtained for Fe1-xPt xSi2 (x=0.03) at the temperature 847 K.

Time‐resolved study on the impact excitation and quenching processes of the 1.54 μm electroluminescence emission of Er ions in InP

1994 ◽  
Vol 76 (6) ◽  
pp. 3714-3719 ◽  
Author(s):  
Tadamasa Kimura ◽  
Hideo Isshiki ◽  
Hiroyuki Ishida ◽  
Shigemi Yugo ◽  
Riichiro Saito ◽  
...  
Keyword(s):  
Impact Excitation ◽  
Time Resolved ◽  
The Impact ◽  
Electroluminescence Emission

High-Temperature Acoustical and Electrical Properties of LGS, LGT and CTGS Resonators

2015 ◽  
Vol 230 ◽  
pp. 267-272 ◽  
Author(s):  
Yuriy Suhak ◽  
Michal Schulz ◽  
Denny Richter ◽  
Holger Fritze
Keyword(s):  
Electrical Conductivity ◽  
Bulk Acoustic Wave ◽  
Measured Temperature ◽  
Temperature Dependent ◽  
Acoustic Characteristics ◽  
Measured Temperature Range ◽  
Temperature Range ◽  
Melting Temperatures ◽  
Acoustic Wave Resonators ◽  
Bulk Acoustic Wave Resonators

Acoustic characteristics and electrical conductivity of CTGS, LGT and LGS bulk acoustic wave resonators operated at the fundamental mode in the temperature range of 20-1470°C are studied. It is shown that LGS and CTGS resonators can be excited piezoelectrically up to 1470 and 1270°C, respectively, which is close to their melting temperatures. The electrical conductivity of CTGS is found to be by at least two and three orders of magnitude lower than that of LGS and LGT, respectively, over the temperature range 400-1000°C. Measurements of temperature dependent electromechanical losses show, that they are at least by two orders of magnitude lower in CTGS comparing to that in LGS within the measured temperature range.

Grain size optimization for high-performance polycrystalline SnSe thermoelectrics

2017 ◽  
Vol 5 (27) ◽  
pp. 14053-14060 ◽  
Author(s):  
Kunling Peng ◽  
Hong Wu ◽  
YanCi Yan ◽  
Lijie Guo ◽  
Guoyu Wang ◽  
...  
Keyword(s):  
Grain Size ◽  
High Performance ◽  
Amorphous Layer ◽  
Thermoelectric Performance ◽  
Size Optimization ◽  
Measured Temperature ◽  
Measured Temperature Range ◽  
Temperature Range ◽  
Average Grain Size ◽  
The Stability

Grain size significantly affects the thermoelectric performance, the thickness of oxidized/amorphous layer and the stability of SnSe polycrystals. As a result, sample Sn0.97Na0.03Se with average grain size around 4 μm achieves a high thermoelectric performance and stability in the whole measured temperature range.

Thermoelectric Properties of the Nanostructured NaPb18-xSnxMTe20 (M=Sb, Bi) Materials

2007 ◽  
Vol 1044 ◽  
Author(s):  
Aurelie Gueguen ◽  
Pierre Ferdinand Poudeu Poudeu ◽  
Robert Pcionek ◽  
Huijun Kong ◽  
Ctirad Uher ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Thermoelectric Properties ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Measured Temperature ◽  
Measured Temperature Range ◽  
Temperature Range ◽  
Properties Of Materials ◽  
P Type

AbstractThe thermoelectric properties of materials with compositions NaPb18-xSnxMTe20 (M=Sb, Bi, x=0, 3, 5, 9, 13, 16 and 18) were investigated in the temperature range 300-670K. All compositions exhibited p-type behavior over the measured temperature range. Electronic properties and transport were tuned through the manipulation of the Pb/Sn ratio. Increasing the Sn fraction results in an increase in electrical conductivity and a decrease in thermopower. The compositions NaPb13Sn5SbTe20 and NaPb9Sn9SbTe20 show a lattice thermal conductivity of ∼1 W/m/K at room temperature.

Features of radiothermoluminescence of polypropylene and ethylene propylenediene elastomer SKEPT-4044 compositions with nanoscale metal-containing fillers

2020 ◽  
pp. 66-73
Author(s):  
A.M. Magerramov ◽  
◽  
N.I. Kurbanova ◽  
M.N. Bayramov ◽  
N.A. Alimirzoyeva ◽  
...  
Keyword(s):  
Transition Temperature ◽  
Molecular Mobility ◽  
Fe3o4 Nanoparticles ◽  
Low Temperatures ◽  
Frost Resistance ◽  
Relaxation Processes ◽  
Ethylene Propylene ◽  
Temperature Range ◽  
Β Relaxation

Using radiothermoluminescence (RTL), the molecular mobility features in the temperature range of 77-300 K were studied for the polypropylene (PP)/ethylene propylene diene elastomer SKEPT-4044 with NiO, Cu2O and Fe3O4 nanoparticles (NPs) based on ABS-acrylonitrile butadiene or SCS-divinyl styrene matrices. It has been shown that the introduction of nanofillers in PP significantly affects the nature and temperature of γ- and β-relaxation processes, while the region of manifestation of the β-process noticeably shifts to the region of low temperatures. Composites with Cu2O NPs have a higher β-transition temperature Tβ than composites with other NPs. It was found that PP/SKEPT-4044 composites with Cu2O NPs with a dispersion of 11-15 nm and acrylonitrile butadiene thermoplastics have optimal frost resistance compared to other compositions.

scholarly journals Full-Field Operational Modal Analysis of an Aircraft Composite Panel from the Dynamic Response in Multi-Impact Test

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1602
Author(s):  
Ángel Molina-Viedma ◽  
Elías López-Alba ◽  
Luis Felipe-Sesé ◽  
Francisco Díaz
Keyword(s):  
Modal Analysis ◽  
Energy Absorption ◽  
High Speed ◽  
Operational Modal Analysis ◽  
Modal Identification ◽  
Image Correlation ◽  
Composite Panel ◽  
Impact Excitation ◽  
Full Field ◽  
The Impact

Experimental characterization and validation of skin components in aircraft entails multiple evaluations (structural, aerodynamic, acoustic, etc.) and expensive campaigns. They require different rigs and equipment to perform the necessary tests. Two of the main dynamic characterizations include the energy absorption under impact forcing and the identification of modal parameters through the vibration response under any broadband excitation, which also includes impacts. This work exploits the response of a stiffened aircraft composite panel submitted to a multi-impact excitation, which is intended for impact and energy absorption analysis. Based on the high stiffness of composite materials, the study worked under the assumption that the global response to the multi-impact excitation is linear with small strains, neglecting the nonlinear behavior produced by local damage generation. Then, modal identification could be performed. The vibration after the impact was measured by high-speed 3D digital image correlation and employed for full-field operational modal analysis. Multiple modes were characterized in a wide spectrum, exploiting the advantages of the full-field noninvasive techniques. These results described a consistent modal behavior of the panel along with good indicators of mode separation given by the auto modal assurance criterion (Auto-MAC). Hence, it illustrates the possibility of performing these dynamic characterizations in a single test, offering additional information while reducing time and investment during the validation of these structures.

Phosphorescence of naphthalene-labelled colloidal polymer particles. The α-methyl relaxation of one microphase in a multicomponent material

1985 ◽  
Vol 63 (1) ◽  
pp. 129-133 ◽  
Author(s):  
Mitchell A. Winnik ◽  
Onder Pekcan ◽  
M. D. Croucher
Keyword(s):  
Decay Process ◽  
Relaxation Processes ◽  
Pure Pmma ◽  
Phosphorescence Quenching ◽  
Complex Morphology ◽  
Freeze Dried ◽  
Decay Times ◽  
Powder Samples ◽  
Pmma Particles ◽  
Multicomponent Material

Nonaqueous dispersions of poly(methyl methacrylate) (PMMA) particles, sterically stabilized with polyisobutylene (PIB), were prepared with naphthalene (N) groups covalently incorporated into the PMMA chains. These materials have a complex morphology of phase-separated PMMA and PIB microdomains, with the N groups in the PMMA microphases. The phosphorescence intensity and decay times of the N groups were measured as a function of temperature over the range 77–295 K for dispersions in methylcyclohexane and for freeze-dried powder samples. An Arrhenius treatment of the radiationlcss decay rate showed a change in slope at −35 °C. The activation energy for the radiationless decay process is 3.8 kcal/mol in the −35 – +22 °C temperature region, identical to that found for pure PMMA by nmr for chain motion associated with the a-methyl relaxation process. We believe that the phosphorescence experiment is sensitive to the diffusion of oxygen and other impurities in the sample. These rates increase as the temperature is raised, enhancing the rate of phosphorescence quenching. These experiments indicate that phosphorescence measurements on labelled samples are suitable for studying relaxation processes within individual microphases of a polyphasic composite material.

Measurements of the Collisionally Quenched Lifetime of CO in Hydrocarbon Flames

1994 ◽  
Vol 48 (9) ◽  
pp. 1118-1124 ◽  
Author(s):  
Sara Agrup ◽  
Marcus Aldén
Keyword(s):  
Laser Induced Fluorescence ◽  
Polyaromatic Hydrocarbon ◽  
Time Decay ◽  
Collisional Quenching ◽  
Time Resolved ◽  
Hydrocarbon Flames ◽  
Effective Lifetime ◽  
Ethylene Flame ◽  
Oxygen Flame ◽  
Different Parts

Time-resolved laser-induced fluorescence (LIF) from CO molecules in hydrocarbon flames was studied. Collisional quenching constants were evaluated on the basis of the exponential decays. Effective lifetime in a methane/oxygen flame was observed to vary between 250 and 400 ps depending on the position within the flame, and from 400 to 600 ps in the non-sooty parts of an ethylene/air flame. Fluorescence, constituting simultaneous spatially and temporally resolved decays, was also registered from various sections along a laser beam that probed different parts of the flame. Spectral recordings revealed not only the expected CO peaks but also, in the ethylene flame, laser-induced emission from C2 Swan bands and from polyaromatic hydrocarbon (PAH) emission that affected the fluorescence time decay in the sooty part of the flame.

Field survey on frost damage to roof tiles under climatic conditions

2016 ◽  
Vol 34 (2) ◽  
pp. 135-149 ◽  
Author(s):  
Chiemi Iba ◽  
Ayumi Ueda ◽  
Shuichi Hokoi
Keyword(s):  
Field Survey ◽  
Winter Season ◽  
Frost Damage ◽  
Climatic Conditions ◽  
Weather Data ◽  
Measured Temperature ◽  
Content Type ◽  
Roof Tile ◽  
Deterioration Process ◽  
The Impact

Purpose – Frost damage is well-known as the main cause of roof tile deterioration. The purpose of this paper is to develop an analytical model for predicting the deterioration process under certain climatic conditions. This paper describes the results of a field survey conducted to acquire fundamental information useful to this aim. Design/methodology/approach – A field survey of roof tile damage by freezing was conducted in an old temple precinct in Kyoto, Japan. Using detailed observations and photographic recordings, the damage progress was clarified. To examine the impact of climatic conditions upon the damage characteristics, weather data and roof tile temperatures were measured and logged in the winter season. Findings – The deterioration process was observed under the climatic conditions associated with the measured temperature of the roof tiles. In particular, it was revealed that the orientation has a significant influence on increasing or decreasing the risk of frost damage. For certain distinctive forms of damage, the deterioration mechanisms were estimated from the viewpoint of the moisture flow and temperature distribution in the tile. Originality/value – This study contributes to the elucidation of the mechanism behind frost damage to roof tiles. The findings will guide the construction of a numerical model for frost damage prediction.

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