Artículos FC IFIS

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Browsing Artículos FC IFIS by Author "Emma Encarnación"

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    Effect of Synthesis temperature on morphological and luminescent properties of lithium fluoride crystals
    (2017-08-08) Emma Encarnación
    A generalization of the site-percolation problem, in which pairs of neighbor sites (site dimers) and bonds are independently and randomly occupied on a triangular lattice, has been studied by means of numerical simulations. Motivated by considerations of cluster connectivity, two distinct schemes (denoted as $S{\cap}^{}B$ and $S{\cup}^{}B$ ) have been considered. In $S{\cap}^{}B$ ($S{\cup}^{}B$ ), two points are said to be connected if a sequence of occupied sites and (or) bonds joins them. Numerical data, supplemented by analysis using finite-size scaling theory, were used to determine (i) the complete phase diagram of the system (phase boundary between the percolating and nonpercolating regions), and (ii) the values of the critical exponents (and universality) characterizing the phase transition occurring in the system.
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    Thermoluminescent response and kinetic parameters of Eu3+ -doped LiF crystals exposed to X-rays.
    (2017-02) Emma Encarnación
    In the present work pure and Eu3+-doped LiF crystals were synthesized through co-precipitation method and the effect of Eu3+ concentration on the thermoluminescent (TL) response is reported. A cubic crystalline phase was determined by XRD for all synthesized samples. The photoluminescence spectra as well as UV–vis absorbance were also analyzed and four emissions bands centered at 592 nm (5D0 → 7F1), 614 nm (5D0 → 7F2), 652 nm (5D0 → 7F3) and 698 nm (5D0 → 7F4) have been observed. The TL response to X-ray irradiation was studied for an exposition of 43 R during a total time of 52 s. The presence of Eu3+ in the samples enhanced the TL signal, due to the Eu3+ ions that are incorporated into the LiF crystalline lattice which promotes the formation of defects in the unit cell. The kinetic parameters (E, b, s) were calculated using the glow-curve shape method. Energy traps around E=1 eV and frequency factors on the order s=108 s−1 were obtained on average, regardless of the Eu3+ concentration. The host of LiF showed the higher characteristic energies and frequency factors, respectively. The 1.0 mol% Eu3+-doped sample was found to have a sensitivity 5 times greater than the host of LiF. The good TL sensitivity to X- ray exhibited by the Eu3+-doped LiF crystals synthesized in this work, suggests that this material should be further studied with respect to other characteristics before being used as a radiation dosimeter.