US 6,290,873 B1Granted

Phosphor preparation method

AssigneeFuji Photo Film Co., Ltd.

InventorsKenji Takahashi, Chiyuki Umemoto, Makoto Funabashi, Yuji Isoda

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Abstract

There is provided a method for preparing a highly accelerated-phosphorescent phosphor whose erasability and after-image characteristic are both improved. Phosphor materials are mixed together to obtain a mixture, and the mixture of phosphor materials is fired in a furnace having a firing region whose capacity is 2 to 500 L per kilogram of the mixture, at a temperature of 550 to 1000° C. while introducing 1 to 200 ml of oxygen in volume at room temperature per liter capacity of the firing region in the furnace, to thereby prepare a phosphor represented by the following compositional formula (I): (Ba1−a, MIIa)FX.bMI.cMIII.dA:xLn (I) wherein, MIIa is alkaline earth metal such as Sr, Ca or Mg; MI is alkali metal such as Li, Na or K; MIII is Al, Ga or In; X is Cl, Br or I; Ln is rare earth element such as Ce, Eu or the like; A is a metallic oxide such as Al2O3; and a, b, c, d and x are numerical values within the ranges of 0≦a≦0.3, 0<b≦2, 0≦c≦2, 5×10−5≦d≦0.5, and 0<x≦0.2.

Claims16

Dependent claims

A method for preparing a rare earth-activated, alkaline earth metal fluorohalide based phosphor, having the formula (Ba1−a,MIIa)FX.bMIX′.cMIIIX″3.dA:

xLn, wherein MII is at least one alkaline earth metal selected from the group consisting of Sr, Ca and Mg;
MI is at least one alkali metal selected from the group consisting of Li, Na, K, Rb and Cs;
MIII is at least one trivalent metal element selected from the group consisting of Al, Ga, In, Tl, Sc, Y, La, Gd and Lu;
X is at least one halogen selected from the group consisting of Cl, Br and I;
each of X′ and X″ is at least one halogen selected from the group consisting of F, Cl, Br and I;
Ln is at least one rare earth element selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Nd, Er, Tm and Yb;
A is at least one metallic oxide selected from the group consisting of Al2O3, SiO2 and ZrO2 and a, b, c, d and x are numerical values within the ranges 0≦a<0.3, 0≦b≦2, 0≦c≦2, 5×10−5≦d≦0.5, and 0≦x≦0.2;
in which phosphor materials are mixed together to obtain a mixture for preparing the rare earth-activated, alkaline earth metal fluorohalide based phosphor, and thereafter the mixture is fired under a weakly reducing atmosphere or a neutral atmosphere, the method comprising the steps of:
(a) placing the mixture in a furnace having a firing region with a capacity of 2 to 500 liters per kilogram of the mixture;
(b) firing the mixture in the furnace at a temperature of 550 to 1000° C.;
and
(c) introducing oxygen into the firing region of the furnace, wherein an amount of oxygen introduced is from 0.1 to 200 ml by volume at room temperature, per liter capacity of the firing region of the furnace.

9 more elements

Dependencies are inferred from the claim text.