ZETA-POTENTIAL OF PHOSPHORS

The zeta potentials of several oxide, sulfide, and oxysulfide phosphor s were measured in isopropyl alcohol (IPA) and IPA containing dissolve d nitrate salts and water. The zeta potentials of phosphors in IPA wit hout dissolved salts are negative. When magnesium nitrate, aluminum ni trate, lanthanum nitrate or yttrium nitrate salts are added at a conce ntration of 5 x 10(-4) M, the zeta potential becomes positive for near ly all of the phosphor-salt combinations measured. Magnesium nitrate c auses the greatest increase in zeta potential, followed by aluminum, y ttrium, and lanthanum nitrate. Neither the addition of small amounts o f water to the IPA nor mechanical rolling exhibited an effect on the z eta potential.