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US5250366A Expired / Lapsed US ⏱️ 0.0 years remaining

Phosphor which emits light by the excitation of X-ray, and a X-ray intensifying screen using the phosphor

Assignee: Nichia Corp
•
Filing: 1992-05-08
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Granted: 1993-10-05
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Expires: 2012-05-08
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Abstract

Abstract The phosphor and the X-rays intensifing screen according to the present inventin emit light by the excitation of X-ray, and they are used for medical and industrial radiography. In addition to the conventional contents of rare earth tantalate and/or rare earth niobate, the phosphor according to the present invention contains a determined quantity of divalent metal. This divalent metal content can make the improvement of the afterglow characteristic and the light emission characteristic of the phosphor. The phosphor according to the present invention is represented by the general formula (I) MyLn 1 -x-(2/3)yDO 4 : xR 3+ (I). In the general formula above, M is at least one divalent metal selected from the group consisting of Be, Mg, Ca, Sr, Ba, Zn and Cd, Ln being at least one selected from the group consisting of Y, Gd, La, and Lu, D being either or both of Ta and Nb, R being at least one selected from the group consisting of Tm, Pr, Sm, Eu, Tb, Dy and Yb or the base substance is self-activating, and y is a value in the range 1×10 -5 ≦y≦1, and x is a value in the range 0≦y≦0.05.

Inventors

  • 👤 Shigeharu Nakajima
  • 👤 Genichi Shinomiya
  • 👤 Mizuho Takeda
  • 👤 Satoru Chikutei

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-09 02:28
CPC Classifications
C; C09; C09K; C09K11/00; C09K11/08; C09K11/77; C09K11/7783; C09K11/7784; C09K11/7786; C09K11/7701; C09K11/7702; C09K11/7703; C09K11/7766; C09K11/7767; C09K11/7768; C09K11/7769; C09K11/7785

Claims Analysis

Total Claims: 7
Claim 1
Independent Claim 186 words
A phosphor which emits light by the excitation of X-rays, and has a composition represented by the formula: M.sub.y Ln.sub.1-x-(2/3)y DO.sub.4 :xR.sup.3+ where: M is Sr, Ln is at least one rare earth element selected from the group consisting of Y, Gd and La, D is Ta, or Ta and Nb, R is Tm, y is a value in the range of 0.030 to 0.075, and x is a value in the range of 0 to 0.05, said phosphor being obtained by a process comprising admixing an oxide of Ln in an amount corresponding to 1-x-(2/3)y parts by mol of Ln, an oxide of D in an amount corresponding to one part by mol of D, an oxide of R in an amount corresponding to x parts by mol of R, a carbonate of M in an amount corresponding to y parts by mol of M and lithium chloride flux to prepare an admixture, and firing said admixture at a temperature sufficient to provide a phosphor having said composition and wherein said phosphor exhibits improved brightness and a smaller afterglow than the same phosphor absent M.
Claim 2
Dependent Claim 186 words
A phosphor which emits light by the excitation of X-rays, and has a composition represented by the formula: M.sub.y Ln.sub.1-x-(2/3)y DO.sub.4 :xR.sup.3+ where: M is Sr, Ln is at least one rare earth element selected from the group consisting of Y, Gd and La, D is Ta, or Ta and Nb, R is Tm, y is a value in the range of 0.030 to 0.075, and x is a value in the range of 0 to 0.05, said phosphor being obtained by a process comprising admixing an oxide of Ln in an amount corresponding to 1-x-(2/3)y parts by mol of Ln, an oxide of D in an amount corresponding to one part by mol of D, an oxide of R in an amount corresponding to x parts by mol of R, a carbonate of M in an amount corresponding to y parts by mol of M and lithium chloride flux to prepare an admixture, and firing said admixture at a temperature sufficient to provide a phosphor having said composition and wherein said phosphor exhibits improved brightness and a smaller afterglow than the same phosphor absent M.
Claim 3
Dependent Claim 21 words
An X-ray intensifying screen comprising a support and a phosphor layer formed on said support comprising the phosphor of claim 1.
Claim 4
Dependent Claim 18 words
The phosphor according to claim 1 having the formula Sr 0 .075 Y 0 .950 TaO 4 .
Claim 5
Dependent Claim 21 words
An X-ray intensifying screen comprising a support and a phosphor layer formed on said support comprising the phosphor of claim 3.
Claim 6
Dependent Claim 22 words
The phosphor according to claim 1 having the formula Sr 0 .030 Y 0 .975 TaO 4 : 0.005 Tm 3+ .
Claim 7
Dependent Claim 21 words
An X-ray intensifying screen comprising a support and a phosphor layer formed on said support comprising the phosphor of claim 5.

References Cited (Backward Citations)

US3758486A Cited
US4032471A Cited
US4225653A Cited
US4473513A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1996-10-04 1997-04-05 1997-10-05 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 2000-10-04 2001-04-05 2001-10-05 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 2004-10-04 2005-04-05 2005-10-05 $7700.00 Window Closed / Lapsed

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