Comparative studies of electron-phonon coupling parameters in the luminescence lines for Zn2SiO4: Mn2+ and Zn2SiO4: En3+ crystals

Abstract

The effects of temperature on the luminescence line 6A1─4T1 of Zn2SiO4: Mn2+ and luminescence lines 5D0 ─7FJ (J = 0, 1, 2, 3, 4) of Zn2SiO4: Eu3+ phosphors are analyzed in terms of both the static effect (characterized by the static parameter A) due to lattice thermal expansion and the dynamic effect (characterized by electron-phonon coupling parameter α′) caused by electron-phonon interaction. The static effect is estimated by dint of the pressure dependences of these line positions. It is found that the static and dynamic effects lead to the thermal blue shift and thermal red shift, respectively, and the observed zero thermal shifts of these line positions are due to the offset of the two effects. By help of an approximate processing, the electron-phonon coupling parameters α′ and static parameters A for these spectral lines are obtained although their thermal shifts are zero. Both the parameters A and α′ for the luminescence lines of 3dn ion Mn2+ in Zn2SiO4 are larger than those of 4fn ion Eu3+ in Zn2SiO4, in especial the parameter α′ in Zn2SiO4: Mn2+ is one order of magnitude greater than those in Zn2SiO4: Eu3+. The reasonableness of these estimated parameters is analyzed. It appears that the processing can extend the area of acquiring electron-phonon coupling parameters to the systems of spectral line with zero thermal shift (but its observed pressure dependence is not zero).