| 摘要 |
<p>PURPOSE: To provide an infrared ray-emission fluorescent substance which is prepared by using a mixture of plural phosphate salts as the starting materials, has very small particle sizes and emitting infrared rays by irradiating an excit ing element having a prescribed wavelength, thus is suitable for ink jetting and can improve the printing quality. CONSTITUTION: This fluorescent substance having the formula (A is at least one selected from the group of Li, K and Na; Z is La, Gd, Y, Yb and Bi) is obtained by using a mixture, as starting substances for phosphoric acid, of at least one of phosphate salt selected from the first group of (A) LiH2 H2 PO4 , NaH2 PO4 , Li2 HPO4 , Na2 HPO4 and of at least one selected from the second group (B) of NH4 H2 PO4 , (NH4 )2 PO4 , H3 PO4 .</p> |
