RT Journal Article
T1 Synthesis of Cerium-Activated Yttrium Aluminate Based Fine Phosphors by an Aerosol Route
A1 Mancic, Lidija
A1 Lojpur, Vesna
A1 Barroso, Ignacio
A1 Rabanal Jiménez, María Eugenia
A1 Milosevic, Olivera
AB Polycrystalline fine powders of yttrium aluminate doped with Ce³⁺ were synthesised by spray pyrolysis of a polymeric pre-cursor, which was obtained by dissolving the corresponding nitrates in a solution of ethylenediaminetetraacetic acid (EDTA) in ethylene glycol (EG). Aerosol decomposition was performed at 550 °C followed by an additional thermal treat-ment (900–1100 °C). The yield of either a single yttrium alu-minium perovskite (YAP) phase or a single yttrium alumin-ium garnet (YAG) phase was investigated as a function of the predefined yttrium/aluminium ratio, the cerium doping concentration, the processing temperature, and the thermal-treatment regime, which included the variation of the heat-ing and cooling rates (dT/dt), the residence time (τ), and the atmosphere. Changes in the composition and structure of the precursor during thermal decomposition were investigated by thermogravimetric and differential thermal analysis (TGA/DTA) and FTIR spectroscopy. The particle morphology and structure were analysed by a combination of scanning electron microscopy and energy-dispersive X-ray spec-troscopy (SEM/EDS) and by highresolution transmission electron microscopy (HR-TEM). The structural refinement was based on the phase identification performed by X-ray powder diffraction (XRPD). The emission spectra were re-corded within the range 325–800 nm by applying excitation wavelengths of 297 (YAP) and 450 nm (YAG). The employed synthesis conditions assured the formation of spherical, non-agglomerated particles with well-developed surfaces and diameters between 200 and 800 nm. For a predefined Y/Al ratio of 1:1, lower processing temperatures combined with longer heat treatments under stationary conditions resulted in a multiphase system, composed of YAP, YAG, and mono-clinic yttrium aluminate (YAM) phases. However, a short heat treatment with a high heating rate (200 °C/min) at higher temperatures results in the formation of a kinetically favoured pure YAP hexagonal phase. On the other hand, for a predefined Y/Al ratio of 3:5, the generation of a thermody-namically favoured pure YAG phase has been confirmed, re-gardless of the applied heat-treatment conditions. Although incomplete, Ce³⁺ introduction into the host matrix has been detected by XRPD and luminescence measurements.
PB Wiley
SN 1099-0682 (online)
SN 1434-1948 (print)
YR 2012
FD 2012-06
LK https://hdl.handle.net/10016/20655
UL https://hdl.handle.net/10016/20655
LA eng
NO The authors gratefully acknowledge the Ministry of Science and Education of the Republic of Serbia (Project No 172035), the University Carlos III (Madrid, Spain), and the Santander Bank (Chairs of Excellence Program for the academic year 2010–2011) for financial support
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RD 7 may. 2024