Rare-earth free yellow-green emitting NaZnPO4:Mn phosphor for lighting   applications
  Manganese doped sodium zinc phosphate phosphor with exceptional features having ultra-violet (UV) to visible absorption (300-470 nm), yellow-green (~543 nm) broad-band photoluminescence (PL) and appreciable color co-ordinates (x=0.39, y=0.58) is reported. It has a crystal structure consists of discrete PO4 tetrahedra linked by ZnO4 and NaO4 distorted tetrahedral such that three tetrahedra, one of each kind, share one corner. The presence of UV sensitive Zn-O-Zn bonds efficient energy transfer to Mn2+ ions resulted in brightest PL and external quantum yield of 63% at 418 nm. Our experiment demonstrated the possibility of producing inexpensive white-light emitting devices for future. 
D. Haranath, S. Mishra, S. Yadav, R. K. Sharma, L. M. Kandpal, N.   Vijayan, M. K. Dalai, G. Sehgal and Virendra Shanker
cond-mat.mtrl-sci