Abstract:
This study of the BaSO4-Bi phosphor has revealed that the accumulated energy
after external optical excitation exhibits specific characteristics. During irradiation with
photon energy exceeding the bandgap, in addition to the intrinsic ultraviolet emission of
the Bi3+ ion, several recombination emissions and emission from the Bi2+ ion are observed.
At 80 K, the recombination luminescence states and Bi2+ ion emission form combined
electronic states. Upon heating of the BaSO4-Bi phosphor, these combined electronic states
decay into recombination emissions at 2.34 eV, 2.4 eV, 3.1 eV, and 2.7 eV, as well as Bi2+ ion
emission at 1.97 eV. It is assumed that the 2.34 eV, 2.4 eV, and 3.1 eV emissions are associated
with the recombination of electrons released from ionized SO3−
4
electron trapping centers
with nonequivalently localized holes in the host lattice. The 2.7 eV emission is attributed to
the decay of an exciton formed by electron–hole recombination near a Bi3+ ion.
