Photoluminescence properties and crystal field analysis of a novel red-emitting phosphor K2BaGe8O18:Mn4+

Novel red-emitting phosphors K2BaGe8O18:Mn4+ (KBGO:Mn4+) were synthesized via the high temperature solid-state reaction method. X-ray diffraction and Rietveld refinements illustrated that pure phase K2BaGe8O18 was obtained from the as-prepared samples. The excitation spectrum of KBGO:0.002Mn(4+) monitored at 666 nm showed a wide band with two obvious peaks at 319 and 468 nm. It can be deconvoluted into four bands with maxima at 313, 350, 391 and 462 nm which corresponded to Mn4+-O2- charge transfer, Mn4+ (4)A(2)-T-4(1), (4)A(2)-(2)A(2) and (4)A(2)-T-4(2) transitions, respectively. Upon 468 nm excitation, the emission spectrum presented a narrow band from 600 to 700 nm (red region) with the maximum emission around 666 nm, which originated from Mn4+ (2)Eg-(4)A(2) transition in GeO6 octahedral environment. Therefore, K2BaGe8O18:Mn4+ phosphor can be considered as a red-emitting component candidate in UV and blue light excited white light-emitting diodes (w-LEDs). (C) 2017 Elsevier Ltd. All rights reserved.