ELECTRON-TRANSFER BETWEEN EU AND TB IN MM GF(4) SYSTEMS

Emission of europium(II) and europium(III) have been observed in SrMgF 4 : xEu, yTb phosphors which are synthesized in Ar or Ar/H-2 flow. The valence state of Eu is influenced by terbium. It is notable that the intensities of the ESR peaks corresponding to EU(2+) are regularly cha nged when terbium ion is incorporated. The typical Tb3d XPS spectrum b elonging to Tb4+ is also found when Eu is codoped. This phenomena can be explained by electron transfer mechanism Eu3+ + Tb3+-->EU(2+) + Tb4 +. And its equilibrium constant is studied by ESR technique.