title: The structure, photoluminescence and influence of temperature on energy transfer in co-doped Ca9La(GeO4)0.75(PO4)6 red-emission phosphors.
abstract: A novel phosphate Ca9La(GeO4)0.75(PO4)6 was investigated to add to the family of phosphate phosphors and application in LEDs. In this work, the single phase red-emission Ce(3+),Mn(2+) co-doped phosphate Ca9La(GeO4)0.75(PO4)6 phosphor was synthesized by the solid-state reaction from both theoretical and practical points of view. The crystal structure was determined by Rietveld refinement and TEM. Its cell parameters are a = b = 10.4077605(2) Å, and c = 37.4714968(1) Å. The characteristic photoluminescence properties were studied in detail using photoluminescence excitation spectra, emission spectra, decay times and thermal quenching properties. Purple and red broad band emission from Ce(3+) and Mn(2+) was detected under excitation at 313 nm. According to this research, the Ca9La(GeO4)0.75(PO4)6:Ce(3+),Mn(2+) phosphor shows high thermal stability in the red-emission area. With the increase of the temperature, the intensity ratio of Mn(2+) and Ce(3+) emission rises rapidly and the purity of red-emission is improved. In order to reasonably explain this special phenomenon, an implicit mechanism between thermal quenching and energy transfer is proposed based on the configurational coordinate diagram. In addition, the mechanism could be helpful for understanding the thermal properties of multiple activators Ce(3+) and Mn(2+) co-doped phosphors as the reference.
authors.affiliation: Key Laboratory for Special Function Materials and Structure Design of the Ministry of the Education, School of Physical Science and Technology, Lanzhou University, Lanzhou, 730000, PR China. wyh@lzu.edu.cn.
authors.forename: Wenjin
authors.initials: W
authors.lastname: Xu
authors.forename: Ge
authors.initials: G
authors.lastname: Zhu
authors.forename: Xufeng
authors.initials: X
authors.lastname: Zhou
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Wang