Articles
  • Theoretical assessment of emission efficiency of Eu2+-doped phosphors based on alkaline-earth network 
  • Hiroaki Onumaa, Ryo Nagumob, Ryuji Miurab, Ai Suzukib, Hideyuki Tsuboib, Nozomu Hatakeyamab, Hiromitsu Takabaa and Akira Miyamotob,*
  • a Department of Chemical Engineering, Graduate School of Engineering, Tohoku University, 6-6-10, Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan b New Industry Creation Hatchery Center, Tohoku University, 6-6-10 Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan c Department of Applied Chemistry, Graduate School of Engineering, Tohoku University, 6-6-10, Aoba, Aramaki, Aoba-ku, Sendai 980-8579, Japan
Abstract
This paper presents the methodology for the estimation of the emission efficiency of Eu2+-doped phosphors based on their structural information. It was figured out from the electronic structures of CaAlSiN3: Eu2+ and SrSiN2:Eu2+ that the lowest unoccupied molecular orbital (LUMO), which is mainly consisted of Eu 5d orbital, is a key factor to show high efficiency of Eu2+ emission. Large contribution of Eu 5d orbital to LUMO is found when there is a strong atomic orbital interaction between alkaline earth atoms and Eu2+ atoms. According to the fact, we defined alkaline earth network (ANet) to represent the magnitude of the interaction of alkaline earth atoms with Eu2+ atoms in the host crystal. We calculated ANet for 10 Eu2+ doped phosphors and correlated them with the experimental values of internal quantum efficiency. ANet has an inversely relationship with internal quantum efficiency. ANet is a good index for qualitatively searching a high efficient Eu2+-doped phosphor because it is calculated only from the structural information of targeted phosphors.

Keywords: Eu2+-doped phosphor; Alkaline-earth network; (n-1)d orbital; Symmetry; Emission efficiency; Computation

This Article

  • 2013; 14(S1): 48-51

    Published on Mar 31, 2013