Giant enhancement of white light emission from Ca(9)Ln(PO4)(7):Eu2+,Mn2+ (Ln = La, Lu, Gd) phosphors achieved by remote aluminum reduction

A series of single-phase Ca(9)Ln(PO4)(7):Eu2+,Mn2+ (Ln = Gd, La, Lu) phosphors with enhanced quantum yields were successfully developed through a topochemical reduction reaction strategy by using elemental aluminum as the reducing agent. Changes were observed both in the spectral shapes and photoluminescence intensities. New broadband emission covering the whole red region and centered at 630 nm from the remote Al reduced Ca(9)Ln(PO4)(7):Eu2+ phosphors was observed, and their PL intensity was tbund to be greatly enhanced. The remote Al reduced Ca9Gd(PO4)7:Eu2+ reaches 4.3 times higher PL than the phosphors prepared by the traditional reduction method under CO atmosphere with the optimal Eu2+ dopant content. Finally, enhanced white-light emissions were gradually obtained by co-doping Eu2+ and Mn2+ in Ca(9)Ln(PO4)(7), and the PLQY value is raised from extremely low to 61.6%. The mechanism for the changes of luminescence behavior was studied and discussed. This research also provides an enlightening reference for the preparation and development of high efficiency single-phase white light emitting phosphors.