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showing 10 items of 2320 documents
Effects of anion size on the electrochemical behavior of H2SO4-structured poly(o-toluidine) films. An ac-electrogravimetry study in acid solutions
2014
International audience; ac -Electrogravimetry has allowed an easy separation of kinetic information to be evaluated for all the transferred species in three different H2SO4-structured poly(o-toluidine) or POT films, View the MathML sourcePOT-NO3−, View the MathML sourcePOT-ClO4− and POT-Cl− films when they are polarized between the pernigraniline (oxidized) and leucoemeraldine (reduced) forms. It is clear that larger anions slow down the electrochemical transitions of POT films, but the effects of anion transfer on hydrated protons and free solvent transfers are affected. For the same polymeric structure of a POT film, the kinetics of all specie transfers have been evaluated considering the…
Luminescence properties of KNbO3 crystals
1997
Thermostimulated luminescence, X-ray-induced luminescence, photostimulated luminescence as well as the time-resolved luminescence and absorption after pulsed electron beam irradiation were studied in KNbO3 crystals at 80–400 K. A correlation between defects causing the luminescence and blue-light-induced IR absorption effects supressing the second harmonic generation efficiency in KNbO3 is discussed.
Unconventional optically active solids in san jose
1990
Characterization of microscopic ferromagnetic defects in thin films using magnetic microscope based on Nitrogen-Vacancy centres
2020
In this work we present results acquired by applying magnetic field imaging technique based on Nitrogen-Vacancy centres in diamond crystal for characterization of magnetic thin films defects. We used the constructed wide-field magnetic microscope for measurements of two kinds of magnetic defects in thin films. One family of defects under study was a result of non-optimal thin film growth conditions. The magnetic field maps of several regions of the thin films created under very similar conditions to previously published research revealed microscopic impurity islands of ferromagnetic defects, that potentially could disturb the magnetic properties of the surface. The second part of the measur…
Raman Spectra of ZrS2 and ZrSe2 from Bulk to Atomically Thin Layers
2016
In the race towards two-dimensional electronic and optoelectronic devices, semiconducting transition metal dichalcogenides (TMDCs) from group VIB have been intensively studied in recent years due to the indirect to direct band-gap transition from bulk to the monolayer. However, new materials still need to be explored. For example, semiconducting TMDCs from group IVB have been predicted to have larger mobilities than their counterparts from group VIB in the monolayer limit. In this work we report the mechanical exfoliation of ZrX2 (X = S, Se) from bulk down to the monolayer and we study the dimensionality dependence of the Raman spectra in ambient conditions. We observe Raman signal from bul…
Review on Polymers for Thermoelectric Applications.
2014
In this review, we report the state-of-the-art of polymers in thermoelectricity. Classically, a number of inorganic compounds have been considered as the best thermoelectric materials. Since the prediction of the improvement of the figure of merit by means of electronic confinement in 1993, it has been improved by a factor of 3-4. In the mean time, organic materials, in particular intrinsically conducting polymers, had been considered as competitors of classical thermoelectrics, since their figure of merit has been improved several orders of magnitude in the last few years. We review here the evolution of the figure of merit or the power factor during the last years, and the best candidates…
<title>Use of AlN ceramics in ultraviolet radiation dosimetry</title>
2003
AlN-Y2O3 ceramics is studied as a material for application in the area of ultraviolet radiation (UVR) dosimetry. The properties of optically stimulated luminescence (OSL) and thermally stimulated luminescence (TL) revealed by AlN ceramics are characterized and considered for practical application. A special attention is devoted to studies of the spectral properties of the material, including stimulated luminescence. Spectral properties of the material make it potentially suitable for dosimetric application both in UV-C region (200-290 nm), where it has the maximum sensitivity, and in UV-B+UV-A (290-350 nm) region, where the spectral behavior of its sensitivity coincides rather well with tha…
Performance data of optically stimulable irradiated materials (doped alkali halides) oriented for imaging and dosimetry purposes
1997
Performance characteristics of a doped alkali halide (KBr:In)-based imaging plate (IP) and dosemeter (D) both the devices utilizing optically stimulated luminescence (OSL) and suitable for UV-light and x-ray energy recording are described. By exploiting (silicon) photodiode array as a photodetector, the detective quantum efficiency of 0.1 for IP (KBr:In) can be achieved. A very wide dynamic range, 1010:1 for UV (6.35 eV) and 1011:1 for x-ray (44 kV tube voltage) OSL recording at the spatial resolution of 1 mm2, is favorable for digital imaging and considerably improves image quality. These possibilities are illustrated by presenting available information capacities, energy consumption per b…
Luminescence of natural α-quartz crystal with aluminum, alkali and noble ions impurities
2019
This work was supported by the Latvian Science Council Grant No lzp-2018/1–0289 .
UV light induced luminescence processes in AlN nanotips and ceramics
2005
UV induced luminescence properties of AlN (Eg = 6.2 eV) have been studied for AlN nanotips and AlN ceramics, using methods of photoluminescence, optically stimulated luminescence and thermoluminescence. In both types of objects the main luminescence band, which appears in prompt and stimulated emission spectra around 400 nm, arises due to presence of oxygen-related defects. The main difference between AlN nanotips and AlN ceramics is observed in excitation spectra and TL properties. Basing on the experimental results it is assumed that several different energy transfer mechanisms occur in AlN. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)