Abstract
We have investigated the applicability of phosphate glasses as host systems for the formation of rare-earth-activated gamma-and x-ray scintillators. Glass scintillators have generally suffered from low light yields, usually attributed to inefficient energy transfer from the glass matrix to the luminescent center. Our research on these phosphate glasses has shown that their structural properties can be readily varied and controlled by compositional alterations. The melting and
pouring temperature of ~1050oC for these phosphate glasses is significantly lower than the processing temperatures generally associated with the formation of silicate glass scintillators. The calcium-sodium phosphate glasses will tolerate relatively high cerium concentrations based on the initial melt compositions, and the light yield for gamma-ray excitation at 662 keV was determined as a function of cerium concentration up to the saturation level. The rare-earthactivated
Ca-Na phosphate glass primary-component decay time was in the range of 32 to 42 nsec for various Ce concentrations with the contribution of the light output of the primary component ranging from 80 to 90%. Studies of the effects of co-doing with both Ce and Gd were also carried out in the case of the Ca-Na phosphate glass hosts. The effects of post-synthesis thermochemical treatments in a variety of atmospheres and at various processing temperatures were also investigated for the Ce-activated Ca-Na phosphate scintillators.
