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Journal of the Electrochemical Society, Vol.157, No.5, J169-J174, 2010
Color Tone Tuning by Partial Sr2+ Substitution of Ba2+ in the White Phosphors Ba1-ySryLa2-xDyxZnO5 (x=0.01-0.2, y=0-0.65)
Ba1-ySryLa2-xDyxZnO5 (x=0.01-0.2, y=0-0.65) phosphors were prepared by a solid-state reaction, and their photoluminescence properties were investigated for the conversion of the UV light emitting diode radiation to white light. The results showed that the maximum emission intensity of the samples without Sr2+ substitution was achieved at the Dy3+ doping level x=0.07 under the UV excitation at 388 nm, and the Commission Internationale del'Eclairage (CIE) chromaticity coordinate of the total emissions was located at (0.256, 0.334). When substituted by Sr2+, the X-ray diffraction showed that the lattice constants and unit cell volumes of Ba1-ySryLa1.93Dy0.07ZnO5 (y=0-0.65) decreased linearly with the increasing Sr2+ content. The color tone of the Ba1-ySryLa1.93Dy0.07ZnO5 phosphors could be tuned by the amount of Sr2+ substitution as the consequence of the induced lattice distortion, which resulted in a change in the local site symmetry around the Dy3+ ions. The CIE chromaticity coordinate (x,y) of Ba1-ySryLa1.93Dy0.07ZnO5 phosphors varied from bluish white (0.256, 0.334) at y=0 to near white (0.315, 0.370) at y=0.65 under the UV excitation at 388 nm.
Keywords:barium compounds;dysprosium compounds;lanthanum compounds;light emitting diodes;phosphors;photoluminescence;strontium compounds