Microcrystals preparation study of LiLa(WO4)2:RE3+ for photonic applications
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Study of the preparation of LiLa(WO4)2:RE3+ microcrystals for photonic applications
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| Author(s): |
Jair Ricardo de Moraes
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Pesquisas Energéticas e Nucleares (IPEN/BT) |
| Defense date: | 2013-05-21 |
| Examining board members: |
Sonia Licia Baldochi;
Jesiel Freitas Carvalho;
Izilda Marcia Ranieri;
Renata Ayres Rocha;
Niklaus Ursus Wetter
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| Advisor: | Sonia Licia Baldochi |
| Abstract | |
In this work, the preparation and characterization of LiLa(WO4)2:RE3+ (LLW:RE) microcrystals as single crystal fibers (micro-pulling-down technique) and as powder (polymerizable complex method) was studied. Concerning the fibers: the pulling rate for LiLa(1-x)Eux(WO4)2 (0≤x≤1) is influenced by the difference between the constituents ionic radii; the tetragonal scheelite-like structure describes all compositions; the Eu incorporation distorts the LLW lattice without reducing the dopant local symmetry; a luminescence quenching for x>0.20 was observed; and the structure modelling for 0≤x≤1 by atomistic simulation was carried out with good precision. Concerning the powder microcrystals: the pH control effect on the preparation of Nd:LLW 1,0 mol% was evaluated; they presented irregular morphology and agglomerates with average sizes of 22-48 μm with higher increase for the calcination temperature than for the time. Concerning the experimental construction of the phase diagram of the system xLi2W2O7-(1-x)La2W2O9: it was confirmed that the LLW (formed in the a homogeneity region of 0.48≤x≤0.55) decomposes peritectically at 1000°C; RE-doping influences the LLW melting; growth, DTA and XRD data of LLW fibers (grown from the compositions based on this diagram) confirmed it. The process of fiber obtaining was optimized with a minimum excess of 1.5 mol% of Li2W2O7. (AU) | |
| FAPESP's process: | 08/10721-9 - Microcrystals preparation study of LiLa(WO4)2:RE3+ for photonic applications |
| Grantee: | Jair Ricardo de Moraes |
| Support Opportunities: | Scholarships in Brazil - Doctorate |