Nanocrystalline Eu{sup}(3+) Doped M{sub}3Al{sub}2O{sub}6 (M: Ba, Ca and Sr) Red Phosphors Prepared by Sucrose-PVA-Metal Ion Complex Route

摘要

Nanocrystalline (<100 nm) red emitting Eu{sup}(3+)-doped M{sub}3Al{sub}2O{sub}6 (M = Ba, Ca and Sr) phosphors were prepared by an aqueous sucrose-PVA-metal ion complex route. The aqueous sucrose-PVA solution includes 20 mol% PVA, and the method is based on the dehydration of a transparent metal ion-sucrose-PVA solution to a highly viscous liquid and then precursor formation by heating at 250°C. The phase formation and the crystallite size measurements were made by X-ray diffraction techniques. Photon correlation analysis revealed that all synthesized phosphor particles range in size from 400 nm to a few microns. The photoluminescence (PL) and PL excitation characteristics have been investigated. All samples have broad CT bands centered at around 269 nm and only the Ca{sub}3Al{sub}2O{sub}6:Eu{sup}(3+) exhibited the characteristic f-f transitions of Eu{sup}(3+) ions mainly located at 396 and 465 nm in comparable levels with the CT band. The emission spectrum of Ca{sub}3Al{sub}2O{sub}6:Eu{sup}(3+) is dominated by the red (5{sup left}D{sub}0 → 7{sup left}F{sub}2) transition band located at 614 nm, however the Eu{sup}(3+) doped Sr{sub}3Al{sub}2O{sub}6 and Ba{sub}3Al{sub}2O{sub}6 phosphors have comparable emission intensity in the red (5{sup left}D{sub}0 → 7{sup left}F{sub}2) and orange (5{sup left}D{sub}0 → 7{sup left}F{sub}1) transition bands. The highest intensity of the red emission was obtained when the Ca{sub}3Al{sub}2O{sub}6:Eu{sup}(3+) phosphor was excited at 396 nm.