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Crespillo M. L. Caballero-Calero O. Joco V. Rivera A. Herrero P. Olivares J. Agulló-López F. 《Applied Physics A: Materials Science & Processing》2011,104(4):1143-1152
The thermal annealing of amorphous tracks of nanometer-size diameter generated in lithium niobate (LiNbO3) by Bromine ions at 45 MeV, i.e., in the electronic stopping regime, has been investigated by RBS/C spectrometry in the temperature
range from 250°C to 350°C. Relatively low fluences have been used (<1012 cm−2) to produce isolated tracks. However, the possible effect of track overlapping has been investigated by varying the fluence
between 3×1011 cm−2 and 1012 cm−2. The annealing process follows a two-step kinetics. In a first stage (I) the track radius decreases linearly with the annealing
time. It obeys an Arrhenius-type dependence on annealing temperature with activation energy around 1.5 eV. The second stage
(II) operates after the track radius has decreased down to around 2.5 nm and shows a much lower radial velocity. The data
for stage I appear consistent with a solid-phase epitaxial process that yields a constant recrystallization rate at the amorphous-crystalline
boundary. HRTEM has been used to monitor the existence and the size of the annealed isolated tracks in the second stage. On
the other hand, the thermal annealing of homogeneous (buried) amorphous layers has been investigated within the same temperature
range, on samples irradiated with Fluorine at 20 MeV and fluences of ∼1014 cm−2. Optical techniques are very suitable for this case and have been used to monitor the recrystallization of the layers. The
annealing process induces a displacement of the crystalline-amorphous boundary that is also linear with annealing time, and
the recrystallization rates are consistent with those measured for tracks. The comparison of these data with those previously
obtained for the heavily damaged (amorphous) layers produced by elastic nuclear collisions is summarily discussed. 相似文献
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J.?Villarroel M.?Carrascosa A.?García-Caba?es O.?Caballero-Calero M.?Crespillo J.?Olivares 《Applied physics. B, Lasers and optics》2009,95(3):429-433
The photorefractive behaviour of a novel type of optical waveguides fabricated in LiNbO3 by swift heavy ion irradiation is investigated. First, the electro-optic coefficient r
33 of these guides that is crucial in the photorefractive effect is measured. Second, two complementary aspects of the photorefractive
response are studied: (i) recording and light-induced and dark erasure of holographic gratings; (ii) optical beam degradation
in single-beam configuration. The main photorefractive parameters, recording and erasing time constants, maximum refractive-index
change and optical damage thresholds are determined. 相似文献
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O.?Caballero-Calero A.?García-Caba?es M.?Carrascosa F.?Agulló-López J.?Villarroel M.?Crespillo J.?Olivares 《Applied physics. B, Lasers and optics》2009,95(3):435-439
The generation of periodically poled structures in waveguides prepared by swift-heavy-ion (SHI) irradiation, i.e. in the electronic
stopping power regime, has been achieved following two different strategies. In one of them we have prepared bulk PPLN samples
by an applied electrical field, followed by irradiation with F ions at 22 MeV. After the ion irradiation, a waveguide showing
a high optical confinement is obtained, preserving the original PPLN structure. The second strategy consisted of electric
periodic poling of previously fabricated swift-ion-irradiated waveguides. To our knowledge this method has not been, so far,
successful for conventional implanted waveguides. The successful fabrication of PPLN structures on novel waveguides prepared
by SHI irradiation offers a promising potential for nonlinear integrated optical devices. 相似文献
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Cristina V. Manzano Adriana A. Rojas Michelle Decepida Begoña Abad Yazmin Feliz Olga Caballero-Calero Diana-Andra Borca-Tasciuc Marisol Martin-Gonzalez 《Journal of Solid State Electrochemistry》2013,17(7):2071-2078
Bi2Te3 films have been grown by constant and pulsed electrochemical deposition. The pulsed deposition was carried out by alternating between a constant potential (potentiostatic mode) and an open circuit potential (galvanostatic mode, where current density is fixed at 0 mA/cm2). The Harris texture analysis was performed to determine the degree of preferred orientation. The results showed that the films were strongly oriented along (1?1?0) direction. The morphology and compositions of the films were then analyzed. Finally, their Seebeck coefficient and electrical resistivity were measured and used to determine the thermoelectric Power Factor of the films for a temperature range between 57 and 107 °C. 相似文献
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