ZETA-POTENTIAL OF PHOSPHORS

The zeta potentials of several oxide, sulfide, and oxysulfide phosphors were measured in isopropyl alcohol (IPA) and IPA containing dissolved nitrate salts and water. The zeta potentials of phosphors in IPA without dissolved salts are negative. When magnesium nitrate, aluminum nitrate, lanthanum nitrate or yttrium nitrate salts are added at a concentration of 5 x 10(-4) M, the zeta potential becomes positive for nearly all of the phosphor-salt combinations measured. Magnesium nitrate causes the greatest increase in zeta potential, followed by aluminum, yttrium, and lanthanum nitrate. Neither the addition of small amounts of water to the IPA nor mechanical rolling exhibited an effect on the zeta potential.