LUMINESCENCE OF BI(3-TRANSFER FROM BI(3+) TO R(3+) (R=EU,DY,SM,TB) INALKALINE-EARTH BORATES() AND THE ENERGY)

At room temperature, the Bi3+ ion shows broad band characters of its l uminescence in Ca2B2O5, M3B2O6 ( M=Ca,Sr ) and SrB4O7. The maxima of t he Bi3+ S-1(0)-->P-3(1) absorption bands are located in the range of 2 40-300nm, but the energy variation of the corresponding P-3(1)-->S-1(0 ) emissions is very large. The maxima of these emission bands change f rom 350nm in Ca3B2O6;Bi3+ to 586nm in SrB4O7:Bi3+. The Stokes shift of the Bi3+ luminescence increases from 6118 cm-1, in Ca2B2O5:Bi3+, to 2 4439 cm-1, in SrB4O7:Bi3+. The emission intensity of the Bi3+ luminesc ence increases with the decreasing Stokes shift. It has been found tha t in Ca2B2O5, the Bi3+ ion could transfer its excitation energy to the R3+ ions ( R=Eu, Dy, Sm, Tb ) , but in, Ca3B2O6 and Sr3B2O6, only Bi3 +-->Eu3+ was observed. No energy transfer from Bi3+ to R3+ was detecte d in SrB4O7.