Fluorescence decay rates of X2UO2Cl4, X = Cs, Rb, and K

1979 ◽  
Vol 57 (3) ◽  
pp. 330-333 ◽  
Author(s):  
A. F. Leung ◽  
K. K. Tsang
Keyword(s):  
Relaxation Time ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Thermal Equilibrium ◽  
Fluorescence Decay ◽  
Decay Rates ◽  
The Other ◽  
Energy Separation ◽  
Pure Crystal ◽  
Fast Relaxation

Fluorescence of alkali uranyl chloride single crystals originates from close-lying doublet levels. The fluorescence decay contains two different decay rates. One rate describes the relaxations of the pure crystal, whereas the other is related to relaxations of impurities or defects in the crystal. The temperature dependence of the two decay rates has been measured. Moreover, it can be explained by assuming that the fluorescent doublet is always in thermal equilibrium with a higher electronic level Ex which has a fast relaxation time. Comparison between measurement and theory of the temperature dependence of the decay rates yields the energy separation ΔE between the fluorescent doublet and Ex. Furthermore, ΔE can be correlated with other spectroscopic measurements.

Plastic Deformations in L10-Ordered Single Crystals with their c/a Ratios Less than Unity

2007 ◽  
Vol 561-565 ◽  
pp. 459-462
Author(s):  
Katsushi Tanaka ◽  
Hiromitsu Ide ◽  
Yoshinori Sumi ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Shear Stress ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Room Temperature ◽  
The Other ◽  
Compressive Deformation ◽  
Positive Temperature ◽  
Plastic Deformations ◽  
Temperature Range ◽  
Critical Resolved Shear Stress

Compressive deformation of L10-ordered single crystals of FePd whose c/a ratio less than unity have been investigated from room temperature to 823 K. The results show that the critical resolved shear stress (CRSS) for octahedral glide of ordinary dislocations is smaller than that of super-lattice dislocations in all the temperature range investigated, that is the opposite sense to the case of Ti-56 mol% Al. The CRSS for ordinary dislocations virtually independent to the temperature. On the other hand, the CRSS for super dislocations exhibits a weak positive temperature dependence from room temperature up to 573 K and decreases in higher temperatures.

POLARISED TEMPERATURE DEPENDENT XANES STUDY OF SUPERCONDUCTING La2-xSrxCuO4-y UNDER- AND OVER-DOPED SINGLE CRYSTALS

2002 ◽  
Vol 16 (09) ◽  
pp. 1327-1339 ◽  
Author(s):  
C. CONCHA ◽  
J. GARCIA ◽  
J. BLASCO ◽  
K. B. GARG ◽  
R. K. SINGHAL ◽  
...  
Keyword(s):  
Phase Transition ◽  
Temperature Dependence ◽  
Single Crystals ◽  
The Other ◽  
Planar Geometry ◽  
Temperature Dependent ◽  
Characteristic Temperatures ◽  
Square Planar ◽  
Planar Systems ◽  
Made In

High resolution XANES measurements have been made at the CuK-absorption edge on two La 2-x Sr x CuO 4-y single crystals; one under-doped (x = 0.13) and the other over-doped (x = 0.19). These measurements have been made in E//ab and E//c directions at several temperatures to compare the doping, orientation and temperature dependence in their behaviour. Broadly speaking, their XANES spectra resemble the typical one from a crystal with square-planar geometry and the various fine structure features assigned to the possible transitions they arise due to, particularly in terms of the fact that the 4p band in Cu splits into 4p(π) and 4p(σ) components in these square-planar systems. However, the temperature dependence of the various features in the spectra from the two crystals appear to be opposite in nature and exhibit some characteristic temperatures at which the trend seems to reverse. All the experimental results and their implication are discussed and a possibility of phase transition of these systems at lower temperatures is hinted at.

Thermal Equilibrium, Metastable and Irreversible Defects in a-Si:H

1989 ◽  
Vol 149 ◽  
Author(s):  
R. A Street ◽  
K. Winer
Keyword(s):  
Relaxation Time ◽  
Low Temperature ◽  
Temperature Dependence ◽  
Thermodynamic Model ◽  
Thermal Equilibrium ◽  
Defect Density ◽  
Defect States ◽  
Different Types ◽  
Metastable Defect ◽  
Deposition Conditions

ABSTRACTMeasurements are reported of metastable defect states in undoped a-Si: H, with the aim of understanding the relation between the different types of metastability. The temperature dependence of the thermal equilibrium defect density agrees well with a proposed thermodynamic model and their relaxation time varies with deposition conditions. The rate of light induced defect creation and annealing in samples deposited at low temperature and with a large initial defect density, decreases progressively as the irreversible defects are removed by annealing.

ANISOTROPY IN THE MAGNETIC SUSCEPTIBILITY OF THE QUASI-ONE-DIMENSIONAL CONDUCTOR Nb3Te4

1995 ◽  
Vol 09 (25) ◽  
pp. 1693-1695 ◽  
Author(s):  
YIN JIANG ◽  
DOU AO-CHUAN ◽  
ZHU MIN ◽  
LIU ZHI-GUO
Keyword(s):  
Magnetic Susceptibility ◽  
Temperature Dependence ◽  
Single Crystals ◽  
The Other ◽  
One Dimensional

We have measured the temperature dependence of the magnetic susceptibility of Nb 3 Te 4 single crystals along the chain direction (c-axis) and perpendicular to the chain direction. Two anomalies were observed, one around 110 K and the other around 50 K, and the anisotropy in the magnetic susceptibility of Nb 3 Te 4 single crystals is obvious.

Uniaxial Reorientation of Octahedral Complex Anions Excited in Triethylammonium Hexachlorostannate (IV) Crystals

1992 ◽  
Vol 47 (1-2) ◽  
pp. 283-287 ◽  
Author(s):  
Takashige Shimizu ◽  
Tetsuo Asaji ◽  
Daiyu Nakamura ◽  
Ryuichi Ikeda
Keyword(s):  
Activation Energy ◽  
Relaxation Time ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Complex Anion ◽  
The Other ◽  
Octahedral Complex ◽  
Complex Ions ◽  
Complex Anions

AbstractThe temperature dependence of the 35Cl NQR spin-latticew relaxation time T1Q has been determined for the three resonance lines observed in [ ( C2H5 ) 3NH]2SnCl6 . The higher frequency lines fade out around 150 K upon heating, whereas the lowest line shows up to room temperature no anomaly, although these three lines are assigned to chlorines belonging to the same complex anion. The T1Q values of the higher two lines decrease exponentially around the fade-out temperature, where T1q of the lowest line shows no such behavior. These results are explained by the onset of uniaxial reorientations of the octahedral complex ions by 90° about the Cl -Sn -Cl axis containing the lowest frequency chlorines. The activation energy ( Ea)of this reorientation (22-24 kJ mol-1 ) is the lowest so far reportd for [SnCl6 ] 2 - ions. Ea about the other axes is 67 kJ mol-1 , indicating a remarkable anisotropic reorientation.

Studies on the Temperature Stability of Pure and Doped Triglycine Sulphate Crystals Using TGA/DTA

2020 ◽  
Vol 10 (3) ◽  
pp. 206-212
Author(s):  
Vijeesh Padmanabhan ◽  
Maneesha P. Madhu ◽  
Supriya M. Hariharan
Keyword(s):  
Thermal Analysis ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Temperature Stability ◽  
Bandgap Energy ◽  
Dsc Analysis ◽  
Slow Cooling ◽  
As Doping ◽  
Similar Dependence ◽  
Temperature Ranges

Aim: To study the temperature stability of TGS doped with ZnSO4, CdCl2, BaCl2, and compare it with that of pure TGS. Objectives: Synthesizing pure and doped TGS and studying their temperature dependence using TGA, DTA, and DSC analysis. Methods: Slow cooling solution growth was used to grow single crystals of pure and doped TGS. The TGA, DTA and DSC analysis was conducted for determining the temperature stability. Results: The thermal analysis of pure and doped TGS shows that the doped samples show a similar dependence on temperature as pure TGS. The temperature of decomposition of pure and doped samples (BTGS, ZTGS, CdTGS) was 226.60°C, 228.38°C, 229.13°C, and 239.13°C respectively. The melting onset of these samples was 214.51°C, 216.04°C, 217.69°C and 216.04°C respectively. Conclusion: The study shows that doping TGS with the above three described materials did not alter their temperature stability considerably. It is a good result as doping TGS, for varying its characteristics like absorbance, reflectance, bandgap energy, etc., which did not alter its temperature stability. Therefore, TGS doped with the above three dopants can be used at the same temperature ranges as of pure TGS but with much-improved efficiency.

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