Red colored phosphor and process for preparing the same
First Claim
1. A particulate red colored phosphor that is red emitting under cathode ray excitation comprising an internal portion consisting of an europium and optionally, samarium activated oxysulfide phosphor represented by the formula
wherein Ln is at least at one element selected from the group consisting of yttrium, gadolinium, lanthanum, lutetium and scandium, and an external portion consisting essentially of an europium and optionally, samarium activated sulfide red colored phosphor represented by the formula (Ca1-x, Srx)S;
Eu, (Sm)
Eu, (Sm) wherein x is a number within the range of 0≦
x≦
0.75.
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Accused Products
Abstract
An europium activated oxysulfide phosphor represented by the formula
Ln.sub.2 O.sub.2 S:Eu,(Sm)
wherein Ln is at least one element selected from the group consisting of yttrium, gadolinium, lanthanum, lutetium and scandium is colored into red by mixing therewith a proper amount of calcium salt solely or together with strontium salt, and firing the resulting mixture at a temperature within the range of 1000° to 1500° C. By the firing, a CaS:Eu,(Sm) phosphor or a (Ca,Sr)S:Eu,(Sm) phosphor having a red body color is produced in an external portion of the Ln2 O2 S:Eu,(Sm) phosphor particle. The red colored phosphor thus obtained is used as a red emitting phosphor of a high contrast cathode ray tube for color television.
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Citations
11 Claims
- 1. A particulate red colored phosphor that is red emitting under cathode ray excitation comprising an internal portion consisting of an europium and optionally, samarium activated oxysulfide phosphor represented by the formula
- space="preserve" listing-type="equation">Ln.sub.2 O.sub.2 S;
Eu, (Sm)
wherein Ln is at least at one element selected from the group consisting of yttrium, gadolinium, lanthanum, lutetium and scandium, and an external portion consisting essentially of an europium and optionally, samarium activated sulfide red colored phosphor represented by the formula (Ca1-x, Srx)S;
Eu, (Sm) wherein x is a number within the range of 0≦
x≦
0.75.- View Dependent Claims (2)
- space="preserve" listing-type="equation">Ln.sub.2 O.sub.2 S;
- 3. A process for preparing a red colored phosphor comprising steps of mixing europium and optionally, samarium activated oxysulfide red emitting under cathode ray excitation phosphor particles represented by the formula
- space="preserve" listing-type="equation">Ln.sub.2 O.sub.2 S;
Eu, (Sm)
wherein Ln is at least one element selected from the group consisting of yttrium, gadolinium, lanthanum, lutetium and scandium, a calcium salt and a strontium salt in stoichiometric ratios wherein (1) the amount of calcium is (1-x) mols in respect of x mols of strontium, x being a number within the range of 0≦
x≦
0.75, and(2) the total amount of calcium and strontium is within the range of 1 to 50 weight % of said oxysulfide phosphor, and firing the resulting mixture at a temperature within the range of 1000°
to 1500°
C.- View Dependent Claims (4, 5, 6, 7, 8, 9, 10, 11)
- space="preserve" listing-type="equation">Ln.sub.2 O.sub.2 S;
Specification