Thermally Activated Processes in CaMoO4 Crystals

2013 ◽  
Vol 200 ◽  
pp. 220-224 ◽  
Author(s):  
Volodymyr Tsybulskyi ◽  
Myron R. Panasyuk ◽  
Ivan M. Solskii ◽  
Viktor Rudyk ◽  
Volodymyr B. Kapustianyk
Keyword(s):  
Activation Energy ◽  
Glow Curve ◽  
High Temperature Annealing ◽  
Thermally Stimulated Luminescence ◽  
Absorption Bands ◽  
X Ray ◽  
Thermally Activated ◽  
Calcium Molybdate ◽  
Activated Processes ◽  
Thermally Stimulated Depolarization

The effect of annealing in the oxygen flow atmosphere of calcium molybdate crystals on their absorption spectra and thermally stimulated luminescence (TSL) glow curve was studied. The thermally stimulated depolarization (TSD), polarization (TSP) currents and temperature dependence of X-ray luminescence of CaMoO4were investigated in the temperature range of 100-320 K. One of the trap detected by TSL was found to disappear after high-temperature annealing of calcium molybdate single crystals. The nature of the absorption bands is discussed. The values of activation energy were calculated for the detected traps.

Raman and dielectric response of BaTi1-x(Mg1/3Nb2/3)xO3 solid solution

2013 ◽  
Vol 03 (04) ◽  
pp. 1350030 ◽  
Author(s):  
Jingji Zhang ◽  
Ludong Ji ◽  
Jiangying Wang
Keyword(s):  
Activation Energy ◽  
Solid Solution ◽  
Raman Spectroscopy ◽  
Dielectric Response ◽  
Critical Concentration ◽  
Structural Evolution ◽  
Dielectric Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Thermally Activated

Structural evolution and dielectric analysis have been performed for BaTi 1-x( Mg 1/3 Nb 2/3)x O 3 solid solutions with x ≤ 0.07, together with the analysis of Raman spectroscopy. X-Ray diffraction and Raman results show a structural evolution from a tetragonal phase to a cubic one with increasing x. Dielectric analysis reveals a low critical concentration corresponding to ferroelectric–relaxor crossover (xc = 0.05). Activation energy with dozens meV is obtained using the Vogel–Fulcher relationship, which is attributed to thermally activated off-center ion hopping.

Electrical Conductivity of Pyrolysed Polyamides Derived from 1,4-Bis(2-Cyano-2-Carboxyvinyl)Benzene and Various Aromatic Diamines

1997 ◽  
Vol 9 (2) ◽  
pp. 189-203 ◽  
Author(s):  
Christoforos A Krontiras ◽  
Michael N Pisanias ◽  
John A Mikroyannidis ◽  
Stavroula N Georga
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Pyrolysis Temperature ◽  
Degree Of Crystallinity ◽  
Chain Mechanism ◽  
Aromatic Diamines ◽  
X Ray ◽  
Thermally Activated ◽  
Heat Treated

The electrical conductivity of three homopolyamides, synthesized from aromatic diamines and identified as PAM, PAP and PAS, was investigated as a function of temperature in the range 100–700 K, following pyrolysis for 24 h in an atmosphere of N2 at temperatures of 550, 700, 800 and 850 °C. X-ray profiles were recorded for the three polymers before and following pyrolysis. The non-heat-treated polymers are amorphous whereas a certain degree of crystallinity is observed following pyrolysis. The observed conductivity covered a range from 10−9 to 10 S cm−1 depending on the polymer and the pyrolysis temperature. The results suggest that the conductivity is thermally activated and is due to two mechanisms, the intra-chain conductivity and the inter-chain conductivity. The activation energy for the intra-chain mechanism varies from 0.36 to 0.01 eV and for the inter-chain mechanism the activation energy varies from 2.76 to 0.08 eV, depending on the pyrolysis temperature for both mechanisms.

scholarly journals Radiation defects in NaCl matrix with reduced lattice symmetry caused by light cation doping and elastic uniaxial deformation

2021 ◽  
Vol 61 (3) ◽  
Author(s):  
K. Shunkeyev ◽  
Zh. Ubaev ◽  
A. Lushchik ◽  
L. Myasnikova
Keyword(s):  
Elastic Deformation ◽  
Elastic Stress ◽  
Electronic Excitations ◽  
Uniaxial Deformation ◽  
Thermally Stimulated Luminescence ◽  
Absorption Bands ◽  
Radiative Relaxation ◽  
X Ray ◽  
Lattice Symmetry ◽  
Subsequent Thermal Annealing

The processes of radiation defect creation and radiative relaxation of electronic excitations under applied local or/and uniaxial elastic deformation have been studied in NaCl crystals by means of optical absorption, luminescence and thermoactivation spectroscopy methods. In NaCl:Li at 80 K, X-ray-induced absorption bands peaked around 3.35 and 4.6 eV have been detected and ascribed to interstitial halide atoms located nearby Li impurity cations, HA(Li) centres. Subsequent thermal annealing of HA(Li) centres leads to the formation of polyhalide centres responsible for the absorption band at 5.35 eV. In an X-irradiated and stressed NaCl:Li crystal (degree of uniaxial elastic deformation of ε = 0.9%), the peak of thermally stimulated luminescence at ~115 K is composed of the ~2.7-eV emission appearing, in our opinion, due to the recombination of the electron, thermally released from an F′ centre, with a hole-type HA(Li) centre. The applied uniaxial elastic stress facilitates the self-trapping of anion excitons in regular regions of a NaCl lattice and impedes the energy transfer by mobile excitons to impurities/defects and, in turn, attenuates the Br-related luminescence peaked at 3.95 eV with respect to the π-emission of self-trapped excitons (~3.35 eV). The 3.95 eV emission has been detected in a natural NaCl crystal containing homologous Br impurity ions.

Synthesis of HTCMgFe for the degradation of indigo carmine through heterogeneous photo-Fenton treatment

MRS Advances ◽  
2020 ◽  
Vol 5 (62) ◽  
pp. 3273-3282
Author(s):  
I. Cosme-Torres ◽  
M.G. Macedo-Miranda ◽  
S.M. Martinez-Gallegos ◽  
J.C. González-Juárez ◽  
G. Roa-Morales ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Treatment Time ◽  
Uv Light ◽  
Indigo Carmine ◽  
Oh Radicals ◽  
Absorption Bands ◽  
Chromophore Group ◽  
X Ray ◽  
Catalytic Sites ◽  
Scanning Electron

AbstractThe heterogeneous catalyst HTCMgFe was used in the degradation of the IC, through the heterogeneous photo-fenton treatment, this material in combination with H2O2 and UV light degraded the dye in 30 min at pH 3. As the amount of HTCMgFe increases the degradation it was accelerated because there are more active catalytic sites of Fe2+ on the surface of the material, which generates a greater amount of •OH radicals. The HTCMgFe was characterized by infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray energy dispersive elemental analysis (EDS). The UV-vis spectrum shows that the absorption bands belonging to the chromophore group of the IC disappear as the treatment time passes, indicating the degradation of the dye.

Structure and Conductivity of Iodine-Doped C60 Thin Films

1994 ◽  
Vol 359 ◽  
Author(s):  
Jun Chen ◽  
Haiyan Zhang ◽  
Baoqiong Chen ◽  
Shaoqi Peng ◽  
Ning Ke ◽  
...  
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Room Temperature ◽  
Conductivity Measurements ◽  
X Ray Diffraction ◽  
Temperature Conductivity ◽  
Room Temperature Conductivity ◽  
X Ray ◽  
Thermally Activated ◽  
Order Of Magnitude

ABSTRACTWe report here the results of our study on the properties of iodine-doped C60 thin films by IR and optical absorption, X-ray diffraction, and electrical conductivity measurements. The results show that there is no apparent structural change in the iodine-doped samples at room temperature in comparison with that of the undoped films. However, in the electrical conductivity measurements, an increase of more that one order of magnitude in the room temperature conductivity has been observed in the iodine-doped samples. In addition, while the conductivity of the undoped films shows thermally activated temperature dependence, the conductivity of the iodine-doped films was found to be constant over a fairly wide temperature range (from 20°C to 70°C) exhibiting a metallic feature.

Validation of New Mathematical Model of Flank Wear by Different Methods

2012 ◽  
Vol 729 ◽  
pp. 169-174 ◽  
Author(s):  
Zoltán Pálmai ◽  
Márton Takács ◽  
Balázs Zsolt Farkas
Keyword(s):  
Activation Energy ◽  
Mathematical Model ◽  
Flank Wear ◽  
Technological Parameters ◽  
Wear Process ◽  
Oxidation Processes ◽  
Industrial Manufacturing ◽  
Thermally Activated ◽  
Optical Electron ◽  
The Mean

Having reviewed the literature on cutting and based on the optical, electron-optical and morphological examinations of wear processes we have reached the conclusion that it is possible to describe the abrasive, adhesive and thermally activated diffusion, oxidation processes in a single mathematical model. The model is a non-linear autonomous differential equation, which can be solved by simple numerical methods. The complex wear equation was validated by the results of the cutting tests performed with P20 carbide on C45 carbon steel. If we have this data, we can calculate the activation energy of the process determining the nature of the wear process. The apparent activation energy of wear is Q=151,7kJ/mol. The model can even be used with changing technological parameters, and the data necessary for the constants of the wear equation may as well be determined even by measurements performed on the tool during industrial manufacturing. By the mean of this data, we can calculate the activation energy determining the nature of the wear process.

X-Ray and Raman Studies of Interlayer Mixing in SimGem Superlattices

1991 ◽  
Vol 220 ◽  
Author(s):  
R. C. Bowman ◽  
P. M. Adams ◽  
S. J. Chang ◽  
V. Arbet-Engels ◽  
K. L. Wang
Keyword(s):  
Activation Energy ◽  
Raman Scattering ◽  
Vacancy Mechanism ◽  
Strained Si ◽  
X Ray ◽  
Scattering Measurements ◽  
Intensity Changes ◽  
Interface Mixing ◽  
Interdiffusion Coefficients

ABSTRACTInterface mixing between the Ge and Si layers in symmetrically strained SimGem superlattices occurs during post growth thermal anneals. Interdiffusion coefficients were obtained from intensity changes in the low angle superlattice x-ray satellites on samples with nominal periodicities between 1.4nm and 5.6nm. A common activation energy of 3.0±0.1 eV was found. The bulk interdiffusion coefficients for SimGem were derived since measurements were made on samples with different layer thicknesses. Intermixing appears to occur by diffusion of Si atoms into the Ge layers via a vacancy mechanism. Raman scattering measurements support this process as well as the formation of Si1−xGex, alloy layers during the anneals.

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