Master Abstract 

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      In my master thesis, we developed the pyrochlore materials by the solid-solid method. We obtained crystallized pellets in pyrochlore phase of very good quality proved by X-ray diffraction. These pellets have a strong emission in the infrared domain as well as in the visible range. The interpretation of the emission spectra makes it possible to record the most intense peaks such as the line (4I13 / 2 → 4I15 / 2) which corresponds to the line used in telecommunication.

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    The study of the optical properties of our materials as a function of the amount of doping Er leads to the phenomenon of self extinction. This phenomenon is obtained following a progressive increase of the active centers in the crystal until the interactions become more and more probable which favors the decrease of the intensity. These luminescent properties are more important when the temperature is varied.

 

     We briefly presented the magnetic properties of these compounds. The experimental data prove that they are antiferromagnetic materials having a temperature TN = 19K. By increasing the temperature, the magnetization decreases and we measured the variation of M as a function of H from (-10 to 10) teslas for temperatures ranging from 5 to 300 ° C. This variation shows the presence of a distinguished hysteresis cycle for materials in the antiferromagnetic phase.

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 Thesis Abstract

       

       In this work, we report the successful preparation of a new non-toxic powder based on Y2Ti2O7 co-doped phosphors Er3+ and Er3+/Yb3+ highly luminescent applied to fingerprint detection.

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       First, we presented the synthesis technique used for the development of pyrochlore  compounds doped with Erbium and co-doped with Yterbium. RX and DLs diffraction measurements allowed us to ensure the purity of the desired phase and the small grain size of our synthesized particles. Using the FTIR characterization, we noted the presence of vibration peaks which confirm the formation of the desired oyrochlore ohase. Then, we were interested in the optical characterizations of the synthesized materials. The study as a function of teh concnetrationof the dopant Ebium ions showed an intensity without any attenuation in the range of concentration studied. the study according to the concentration of Yterbium allowed us to optimize the best performance which enhances the detection of latent fingerprints.

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            For the application aspect, we used the optimized co-doped YTO phosphors to detect fingerprints on the surface of different objects among which we chose several items commonly used in daily life such as glass, CD-Rom, aluminum paper, and plastic where latent fingerprints are often left. The high contrast and low background interference, holding important application in fingerprint identification. We ended this study by a rigorous analysis of teh qualiyu of the extracted minutiae using a fingerprint detection algorithm in order to demonstrate the competitive of our sample knowing that the matching techniques depend on the image quality. 

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 Publications  

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1) Mouna Gouiaaa, Ines Bennour, Lamia Rzouga Haddada, Alessandra Toncelli, Jihua Xu, Aïcha Mbarek, Aldo Moscardini, Najoua Essoukri Ben Amara, Ramzi Maalej

Spectroscopic characterization of Er,Yb:Y2Ti2O7 phosphor for latent fingerprint detection

Physica B: Condensed Matter Volume 582, 1 April 2020, 412009

https://doi.org/10.1016/j.physb.2020.412009

 

2) Alessandra Toncelli, Jihua Xu, Mouna Gouiaa, Ramzi Maalej

Spectroscopic characterization of Er, Yb: Y2Ti2O7 nanoparticles for forensic applications

The European Conference on Lasers and Electro-Optics, ce_p_22

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