Tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor and radiaiton image storage panel

• US 5,534,191 A
• Filed: 12/27/1994
• Issued: 07/09/1996
• Est. Priority Date: 12/27/1993
• Status: Expired due to Term

• Current Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Original Assignee: Fuji Photo Film Co Limited (Fujifilm Holdings Corporation)
• Inventors: Takahashi, Kenji, Hasegawa, Kazuhiro, Kojima, Yasushi
• Primary Examiner(s): KOSLOW, CAROL M
• Application Number:
  US08/364,260
• Time in Patent Office: 560 Days
• Field of Search: 252/301.4 H, 250/484.4
• US Class Current: 252/301.40H
• CPC Class Codes: C09K 11/7705 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/772 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7733 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7748 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7763 with alkali or alkaline earth metals
• CPC Class Codes: C09K 11/7773 with alkali or alkaline earth metal
• CPC Class Codes: C09K 11/7791 with alkali or alkaline earth metals

Abstract

Disclosed is a tetradecahedral rare earth activated alkaline earth metal fluorohalide stimulable phosphor of the formula (I):

Ba.sub.1-x M.sup.II.sub.x FX:yM.sup.I,zLn                  (I)

wherein M^II is Sr or Ca; M^I is Li, Na, K, Rb or Cs; X is Cl, Br or I; Ln is Ce, Pr, Sm, Eu, Gd, Tb, Tm or Yb; and 0≦x≦0.5, 0≦y≦0.05 and 0<z≦0.2. Also disclosed are a process for the preparation of the above stimulable phosphor and a radiation image storage panel.

Claims

1. A process of the preparation for a tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor represented by the formula (I):

space="preserve" listing-type="equation">Ba.sub.1-x M.sup.II.sub.x FX;

yM.sup.I,zLn (I)

wherein M^II is at least one alkaline earth metal selected from the group consisting of Sr and Ca;

M^I is at least one alkaline metal selected from the group consisting of Li, Na, K, Rb and Cs;

X is at least one halogen selected from the group consisting of Cl, Br and I;

Ln is at least one rare earth element selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Tm and Yb; and

x, y and z are numbers satisfying the conditions of 0≦

x≦

0.5, 0≦

y≦

0.05 and 0<

z≦

0.2, respectively, which comprises the steps of;

preparing an aqueous solution which contains BaX₂, a halide of Ln, a halide of M^II if x in the formula (I) is not 0, and a halide of M^I if y in the formula (I) is not 0 and in which the concentration of BaX₂ is not more than 1.4 mol./l;

adding an aqueous solution of an inorganic fluoride to the above-prepared solution under the condition that the temperature of the latter solution is kept at 20°

-100°

C. to precipitate precursor crystals of the tetradecahedral rare earth activated alkaline earth rectal fluorohalide phosphor;

separating the precursor crystals from the aqueous solution; and

firing the precursor crystals under the condition that the fired crystals are not sintered.

2. The process of the preparation for the tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor as defined in claim 1, wherein the inorganic fluoride is ammonium fluoride or an alkaline metal fluoride.

5. A tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor prepared according to the process of claim 1.

6. A tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor prepared according to the process of claim 2.

3. A process of the preparation for a tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor represented by the formula (I):

space="preserve" listing-type="equation">Ba.sub.1-x M.sup.II.sub.x FX;

yM.sup.I,zLn (I)

wherein M^II is at least one alkaline earth metal selected from the group consisting of Sr and Ca;

M^I is at least one alkaline metal selected from the group consisting of Li, Na, K, Rb and Cs;

X is at least one halogen selected from the group consisting of Cl, Br and I;

Ln is at least one rare earth element selected from the group consisting of Ce, Pr, Sm, Eu, Gd, Tb, Tm and Yb; and

x, y and z are numbers satisfying the conditions of 0≦

x≦

0.5, 0≦

y≦

0.05 and 0<

z≦

0.2, respectively, which comprises the steps of;

preparing an aqueous solution which contains an ammonium halide, a halide of Ln, a halide of M^II if x in the formula (I) is not 0, and a halide of M^I if y in the formula (I) is not 0 and in which the concentration of the ammonium halide is in the range of 2.5 mol./l to 4.5 mol./l;

adding an aqueous solution of an inorganic fluoride and an aqueous solution of BaX₂ to the above-prepared solution under the conditions that the temperature of the latter solution is kept at 20°

-100°

C. and that the amount of fluoride in the former solution and the amount of Ba in the latter solution are controlled to give a constant ratio to precipitate precursor crystals of the tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor;

separating the precursor crystals from the aqueous solution; and

firing the precursor crystals under the condition that the fired crystals are not sintered.

4. The process of the preparation for the tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor as defined in claim 3, wherein the inorganic fluoride is ammonium fluoride or an alkaline metal fluoride.

7. A tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor prepared according to the process of claim 3.

8. A tetradecahedral rare earth activated alkaline earth metal fluorohalide phosphor prepared according to the process of claim 4.