Synthesis of Ca4GdO ( BO3 ) 3 : Eu3 + , Al3 + by Sol-Gel Processing and Its Luminescence Properties

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Single phase of and codoped was successfully prepared by sol-gel processing at 1000°C, which is 400°C lower than that of solid-state reaction. Morphology analysis reveals that the synthesized phosphors have nonagglomerated, uniform, small particle size and sphere-like morphology without the grinding process. The photoluminescence properties of and activated phosphor prepared by sol-gel processing under UV and vacuum-UV excitation were studied and compared to the bulk synthesized by solid-state reaction. The broad bands centered at about 181 and 248 nm were obtained in their excitation spectra, which are assigned to the absorption of the host crystal and the charge transition (CT) band of . The broad band at about 135–160 nm was observed in this phosphor for the first time. By calculating, the broad band about 135–160 nm could be assigned to the CT band and f–d transition of . The excitation intensity was enhanced by codoping with into the lattices. Under 254- and 147-nm excitation, the intense pure red emission was observed in their emission spectra and the sample prepared by the sol-gel process had higher luminescence intensity than that derived from solid-state reaction.