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White‐Light and Yellow/Blue Photoluminescence Emission Based on Dy 3+ ‐Doped SiO 2 –Gd 2 O 3 Composites
Author(s) -
Rocha Leonardo Alves,
Schiavon Marco Antonio,
Ribeiro Sidney José Lima,
Ferrari Jefferson Luis
Publication year - 2016
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.14316
Subject(s) - chromaticity , monoclinic crystal system , analytical chemistry (journal) , photoluminescence , materials science , doping , excited state , luminescence , phosphor , crystallography , crystal structure , chemistry , optics , atomic physics , physics , optoelectronics , chromatography
This work attempts to obtain Dy 3+ ‐doped SiO 2 –Gd 2 O 3 by sol–gel process , with a molar ratio of 70Si 4+ –30Gd 3+ and Dy 3+ concentrations of 0.1, 0.3, 0.5, and 1 mol%. Heat treatment at temperatures of 1000°C, 1100°C, 1200°C, and 1300°C have been performed. From XRD , the Gd 2 O 3 cubic phase was observed at 1000°C and 1100°C, at 1200°C also were observed Gd 2 O 3 monoclinic phase, predominant at 1300°C. The band‐gap values vary between 4.4 and 5.3 eV, showing dependence on the crystalline phase. Under UV excitation, emission spectra show bands assigned to the Dy 3+ transitions: 4 F 9/2 → 6 H 15/2 (484 nm), 4 F 9/2 → 6 H 13/2 (572 nm), and 4 F 9/2 → 6 H 11/2 (668 nm). The excitation at 275 nm has shown more effective. The ratio between the most intense emission bands (yellow/blue) show values around 0.84 and 1.63. CIE chromaticity diagrams show color coordinates at blue, yellow, and white regions, as a function of Dy 3+ concentration and heat treatment. The lifetime values of excited state 4 F 9/2 were around 0.20 and 0.69 ms. The morphology of particles changed from spherical to coral‐like shape as a function of heat treatment are observed. The sol–gel process showed to be an interesting route to obtain Dy 3+ ‐doped binary system materials.