| abstract |
A hexagonal NaLnF 4 :Yb 3 + , Er 3 + (Ln represents the elements Y, La, Gd and/or Lu) has been found to be an efficient phospor emitting green light with infrared excitation, which can be prepared by firing a mixture of Na 2 SiF 6 and coprecipitated Ln 1 -y -z Yb y Er z F 3 . Optimum firing conditions for synthesis of NaLnF 4 :Yb 3 + , Er 3 + have been found to be such that: n A. the decomposition reaction of Na 2 SiF 6 to (2NaF + SiF 4 ) is complete, n B. liquid NaF-Ln 1 -y -z Yb y Er z F 3 and hexagonal NaLn 1 -y -z Yb y Er z F 4 are co-existent, and n C. the hexagonal-to-cubic phase transition does not occur in NaLn 1 -y -z Yb y Er z F 4 . n When pumped by a Si-doped GaAs diode, properly prepared NaY 0 .57 Yb 0 .39 Er 0 .04 F 4 emit under infrared stimulation green light 4 to 5 times as bright as commercially available LaF 3 :Y 3 + , Er 3 + . |