scholarly journals Электрически активные состояния захвата и переноса заряда, обусловливающие медленную рекомбинацию в кристаллах бромида таллия при низких температурах

2018 ◽  
Vol 52 (2) ◽  
pp. 171
Author(s):  
В. Кажукаускас ◽  
Р. Гарбачаускас ◽  
С. Савицки
Keyword(s):  
Activation Energy ◽  
Electric Field ◽  
Single Crystals ◽  
Applied Electric Field ◽  
Thermal Activation ◽  
Thermal Quenching ◽  
Activation Energies ◽  
Trap States ◽  
Optical Generation ◽  
Stockbarger Method

AbstractTlBr single crystals grown by the Bridgman–Stockbarger method are studied. It is established that frozen-conductivity effects manifest themselves under interband excitation by light at temperatures below 200 K. Herewith, clearly pronounced superlinear dependences of the induced photoconductivity on the strength of the applied electric field manifest themselves. The results of studying thermally stimulated conductivity evidence that these phenomena can be associated with the filling of trap states with thermal activation energies of 0.08–0.12 eV. This state can be removed due to thermal quenching at temperatures of ≳180 K because of the emptying of energy states with an activation energy of 0.63–0.65 eV filled after optical generation.

Shape of piezoelectric hysteresis loop for non-ferroelastic switching

2003 ◽  
Vol 784 ◽  
Author(s):  
A. K. Tagantsev ◽  
P. Muralt ◽  
J. Fousek
Keyword(s):  
Thin Films ◽  
Electric Field ◽  
Hysteresis Loop ◽  
Single Crystals ◽  
Applied Electric Field ◽  
Piezoelectric Coefficient ◽  
Hysteresis Loops ◽  
Simple Theory ◽  
The Difference

ABSTRACTA simple theory for the shape of the piezoelectric hysteresis loops (piezoelectric coefficient d vs. applied electric field E) is developed for the case of non-ferroelelastic 180° switching in ferroelectrics. The theory provides explanations for specific features of piezoelectric hysteresis loops, which have been observed in single crystals, thin films and in ceramics in particular. The piezoelectric coefficient may show a “hump”, i.e. when E decreases from the tip of the loop down to zero, d passes through a maximum, and a “nose”, i.e. a self-crossing of the loop close to its tips. The theory also explains the difference in the coercive fields seen in the polarization and piezoelectric loops.

Thermoluminescence study on TlGaSSe layered single crystals

2014 ◽  
Vol 28 (16) ◽  
pp. 1450133 ◽  
Author(s):  
Serdar Delice ◽  
Nizami M. Gasanly
Keyword(s):  
Single Crystals ◽  
Heating Rate ◽  
Thermal Quenching ◽  
Activation Energies ◽  
Temperature Peak ◽  
Heating Rates ◽  
Quenching Effect ◽  
Defect Centers ◽  
General Order ◽  
Maximum Temperatures

The defect centers in TlGaSSe single crystals have been investigated by performing thermoluminescence (TL) measurements with various heating rates between 0.5 K/s and 1.0 K/s in the temperature range of 10–180 K. The TL spectra, with peak maximum temperatures at 39 K and 131 K, revealed the existences of two defect levels. Curve fitting, initial rise and peak shape methods were used to determine the activation energies of two defect centers. The experimental results also showed that the trapping process was dominated by second-order kinetics for the trap related with low temperature peak while the general order (mixed order) kinetics was dominant for the trap donated to high temperature peak. Furthermore, heating rate dependences and traps distributions were studied for two defect centers separately. Thermal quenching effect dominates the behavior of these defects as the heating rate is increased. Also, quasi-continuous distributions were established with the increase of the activation energies from 16 meV to 27 meV and from 97 meV to 146 meV for the traps associated with the peaks observed at low and high temperatures, respectively.

Influence of Er and O doses in Er-related emission in Al0.70Ga0.30As:Er

2001 ◽  
Vol 692 ◽  
Author(s):  
Shin-ichiro Uekusa ◽  
Tomoyuki Arai
Keyword(s):  
Activation Energy ◽  
Temperature Dependence ◽  
Room Temperature ◽  
Thermal Quenching ◽  
Activation Energies ◽  
Optimum Dose ◽  
Radiative Efficiency ◽  
Gaas Substrates ◽  
Pl Intensity

AbstractEr ions with doses ranging from 1×1013 cm−2 to 1×1015 cm−2 were implanted into Al0.70Ga0.30As on GaAs substrates. at 800 °C. Photoluminescence (PL) intensity of Er-related emission around 1.54 μm was enhanced by co-implanted oxygen (O). The optimum dose of Er ion was 1×1014 cm−2 and O ion was 1×1015 cm−2, respectively. Furthermore, from the temperature dependence of the PL intensity of sample implanted with the optimum dose, we estimated the values of E1, E2, and E3, the activation energies in order to investigate the rapid thermal quenching of Er ion in Al0.70Ga0.30As. We found that PL intensity of Er-related emission, in addition to O dose, was enhanced approximately twenty two times at room temperature. And from the temperature dependence of the lifetime of the optimum dose of Er and O, the value 245meV of EA, the activation energy for the decrease of the lifetime, was nearly equal to the value 235meV of E3. Based on the result, the decrease of the lifetime confirms that the radiative efficiency is lower; therefore, we propose that rapid thermal quenching occurs at temperatures above 200 K due to the decrease of the radiative efficiency.

scholarly journals The Orientation Polarization in Hexagonal Ice Parallel and Perpendicular to the c-axis

1978 ◽  
Vol 21 (85) ◽  
pp. 259-276 ◽  
Author(s):  
G. P. Johari ◽  
S. J. Jones
Keyword(s):  
Activation Energy ◽  
Electric Field ◽  
Single Crystals ◽  
Relative Permittivity ◽  
Gold Foil ◽  
Exponential Factor ◽  
Orientation Polarization ◽  
Hexagonal Ice ◽  
Polycrystalline Ice ◽  
Oriented Parallel

AbstractThe relative permittivity and loss of zone-refined single crystals of hexagonal ice have been measured in the temperature range 200–271 K and frequency range 0.5 HZ–0.2 MHz, using brass, stainless steel, and gold-foil electrodes. The c-axis of the crystal was oriented parallel to the electric field in 14 samples and perpendicular to the field in 8 samples. The equilibrium relative permittivity of orientation polarization ϵ0, parallel and perpendicular to the c-axis, is 96.5±1 and the average relaxation time τay is 36 μs at 265±0.5K; ϵ0 = 124±1.5 and τav = 30 ms, at 210 K. The magnitude of the orientation polarization obeys the Curie-Weiss equation with T0= 15±2 K for both the orientations. These values are in contrast with the c. 17% difference in ϵo for the two orientations reported in the literature. The extrapolated limiting high-frequency relative permittivity ϵ∞, measured for both the orientations, is indistinguishable within 0.5%.The logarithmic plot of the product of τav and temperature against the reciprocal temperature is linear in the range 210–271 K and gives an activation energy and a pre-exponential factor of 51±2 kJ mol–1 and 0.93±0.22 ps K respectively, for both the orientations of the c-axis with respect to the electric field. The decrease in activation energy which has been reported to occur in polycrystalline ice and in single crystal ice near 230 K is not found until a temperature of 210 K. Single crystals of ice stored in the dielectric cell, after the completion of measurements, for periods ranging from 1–11 weeks at 253±2 K showed no change in their ϵ0, τav, ϵ∞ that could be attributed to the effect of ageing on the orientation polarization.

Analysis of defect formation in Nb-doped SrTiO3 by impedance spectroscopy

2001 ◽  
Vol 16 (1) ◽  
pp. 192-196 ◽  
Author(s):  
Seong-Ho Kim ◽  
Jung-Ho Moon ◽  
Jae-Hwan Park ◽  
Jae-Gwan Park ◽  
Yoonho Kim
Keyword(s):  
Activation Energy ◽  
Impedance Spectroscopy ◽  
Grain Boundary ◽  
Single Crystal ◽  
Grain Boundaries ◽  
Thermal Activation ◽  
Oxygen Vacancies ◽  
Defect Formation ◽  
Activation Energies ◽  
Single Grain

The thermal activation energies for conduction of Nb-doped SrTiO3 grains and grain boundaries have been investigated by impedance spectroscopy. First, to observe the effect of electrode/SrTiO3 bulk interface, the varied impedances of SrTiO3 single crystal were measured with temperatures. The activation energy of an electrode/bulk interface was determined to be 1.3 eV, whereas that of bulk was 0.8 eV. When the impedances of Nb-doped SrTiO3 ceramics were measured, it was suggested that the more precise impedance values of a single grain and a single grain to grain junction be obtained using a microelectrode method. The activation energies for a grain, a grain boundary, and an electrode/bulk interface were determined to be about 0.8, 1.3, and 1.5 eV, respectively. From these measured results, it was suggested that the activation energy, 0.8 eV, measured in grain was originated from oxygen vacancies and the activation energy, 1.3 eV, in grain boundary was from strontium vacancies.

Effects of doping concentration on thermal activation energy of trap centers in irradiated LiF:Mg2+ single crystals

2013 ◽  
Vol 88 (4) ◽  
pp. 375-379 ◽  
Author(s):  
H. Sadeghi ◽  
M. R. Jalali ◽  
S. Mohammadi ◽  
H. Jahanbakhsh ◽  
M. Kavosh
Keyword(s):  
Activation Energy ◽  
Single Crystals ◽  
Thermal Activation ◽  
Doping Concentration ◽  
Thermal Activation Energy

Development of Lead-Free Piezoelectric Materials Using Domain Wall Engineering

2006 ◽  
Vol 320 ◽  
pp. 151-154
Author(s):  
Satoshi Wada ◽  
Koichi Yako ◽  
Tomomitsu Muraishi ◽  
Hirofumi Kakemoto ◽  
Takaaki Tsurumi
Keyword(s):  
Barium Titanate ◽  
Domain Wall ◽  
Electric Field ◽  
Single Crystals ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Piezoelectric Materials ◽  
Domain Size ◽  
Lead Free ◽  
Gradient Domain

For the [111] oriented barium titanate (BaTiO3) single crystals, the patterning electrode was applied to induce the finer engineered domain configurations with domain size of 3 2m. The poling treatment was performed at 134 °C under electric fields below 6 kV/cm to inhibit the burning of the patterning electrode with photoresist. As the results, the gradient domain sizes from 3 to 8-9 2m were induced into the 31 resonator. The d31 was measured at -243.2 pC/N, and this value was almost 70 % of the expected d31 of –337.7 pC/N for the resonator with domain size of 3 2m. This difference was originated from lower applied electric field below 6 kV/cm. However, this study was revealed that the patterning electrode was very powerful tool to induce much finer domain sizes below 5 2m.

scholarly journals Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) Material for Actuator Applications

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
Hana Uršič ◽  
Marina Santo Zarnik ◽  
Marija Kosec
Keyword(s):  
Solid Solution ◽  
Electric Field ◽  
Single Crystals ◽  
Functional Properties ◽  
Applied Electric Field ◽  
Thick Films ◽  
Promising Material

Due to its large piezoelectric and electrostrictive responses to an applied electric field the (1−x)Pb(Mg1/3Nb2/3)O3–xPbTiO3 (PMN-PT) solid solution has been widely investigated as a promising material for different actuator applications. This paper discusses some of the recent achievements in the field of PMN-PT piezoelectric and electrostrictive actuators manufactured from PMN-PT single crystals, bulk ceramics, or thick films. The functional properties of PMN-PT materials and some representative examples of the investigated PMN-PT actuator structures and their applications are reported.

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