# US 7,410,599 B2 · Stable green phosphor and plasma display panel using the same

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- Number: US 7,410,599 B2
- Document ID: US7410599B2
- Status: Granted
- Kind: B2
- Application number: 11/069,744
- Filed: 2005-03-01
- Published: 2006-09-07
- Granted: 2008-08-12
- Earliest claimed: 2005-03-01
- Assignees: Matsushita Electric Industrial Co., Ltd.
- Inventors: Padmanabha Rao Ravilisetty
- Web page: https://patentgrep.com/patent/US7410599B2

## CPC

- H01J 11/42: Fluorescent layers
- C09K 11/7774: {Aluminates}
- H01J 11/12: with main electrodes provided on both sides of the discharge space
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- C09K: MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE

## Abstract

A green emitting lanthanide aluminate phosphors activated with manganese and alkali halide, and blends thereof, for plasma display panels (PDP) and methods for their preparation are provided. The phosphor has an empirical formula: Ln2-x-yB22O36:Mnx.Ay wherein Ln is a lanthanide metal selected from the group consisting of: La, Y, Gd, Tb, and a combination thereof, wherein La is: 0.57≦La≦1.782; Y is: 0≦Y≦0.19; Gd is: 0.198≦Gd≦0.95; and Tb is: 0≦Tb≦0.19; A is selected from the group consisting of: Li, Na, K and a combination thereof; B is selected from the group consisting of: Al and a combination of Al and Ga; x is 0.01≦x≦0.1; and y is 0.01≦y≦0.1. These phosphors have a band emission in green region, peaking at 515 nm when excited by 147 and 173 nm radiation from Xenon gas mixture of various compositions, a uniform particle size distribution (0.01 to 10 microns) appropriate for thin phosphor screens required for a variety of flat panel display and lamp applications and exhibit high brightness, good color saturation, good stability and shorter persistence under VUV excitation.

## Claims

### Claim 1

A green emitting Mn and alkali metal activated lanthanide aluminate phosphor having the empirical formula:
Ln(2-x-y)B22O36:Mnx,Ay
wherein:
Ln is a combination of La, Y, Gd, and Tb, wherein La is: 0.57≦La≦1.782; Y is: 0≦Y ≦0.19; Gd is: 0.198≦Gd≦0.95; and Tb is: 0≦Tb≦0.19;
A is selected from the group consisting of: Li, Na, K and a combination thereof;
B is selected from the group consisting of: Al and a combination of Al and Ga;
x is from about 0.01 to about 0.1; and
y is from about 0.01 to about 0.1.

### Claim 2 (depends on 1)

A green emitting Mn and alkali metal activated lanthanide aluminate phosphor according to claim 1, prepared by a method comprising the steps of:
mixing a source of an alkali metal, a source of manganese, a source of lanthanide and a source of aluminum in an acid medium to form dilute aqueous solution;
removing at least a portion of water from said dilute aqueous solution to form a gel;
heating said gel at a temperature sufficient to remove excess water thereby converting said gel into a gel powder; and
thermally decomposing said gel powder at a temperature and for a length of time sufficient to produce said phosphor.

### Claim 3 (depends on 2)

The phosphor of claim 2, wherein said source of alkali metal is an alkali metal salt, said source of lanthanide is a lanthanide salt, said source of manganese is manganese salt, and said source of aluminum is an organic precursor providing aluminum.

### Claim 4 (depends on 3)

The phosphor of claim 3, wherein said alkali metal salt is selected from the group consisting of: alkali halides, alkali nitrate, alkali carbonate, alkali hydroxide, and mixtures thereof; said lanthanide salt is selected from the group consisting of: lanthanide oxalate, lanthanide nitrate, lanthanide oxide, and mixtures thereof; said manganese salt is selected from manganese halides, manganese nitrate, manganese carbonate, manganese hydroxide, and mixtures thereof; and said organic precursor providing aluminum is selected from the group consisting of: aluminum isopropoxide, aluminum s-butoxide, and mixtures thereof.

### Claim 5 (depends on 2)

The phosphor of claim 2, wherein said gel is dried to form said gel powder prior to thermal decomposition.

### Claim 6 (depends on 2)

The phosphor of claim 2, wherein said gel is vacuum dried to form said gel powder as an aerogel prior to thermal decomposition.

### Claim 7 (depends on 2)

The phosphor of claim 2, wherein said gel is spray dried to form said gel powder prior to thermal decomposition.

### Claim 8 (depends on 2)

The phosphor of claim 2, wherein said gel is thermally decomposed in an open atmosphere at a temperature from abut 1000° C. to about 1400° C. and then at a temperature from about 1000° C. to about 1300° C. in forming gas.

### Claim 9 (depends on 1)

The phosphor of claim 1, wherein said phosphor exhibits a relative intensity (AU) at 147 nm excitation from about 90 to about 100 and relative intensity (AU) at 173 nm excitation from about 90 to about 5 with half width from about 23 to about 25 nm.

### Claim 10 (depends on 1)

The phosphor of claim 1, wherein said phosphor exhibits short time persistence (10% of initial intensity) from about 7 ms to about 10 ms.

### Claim 11 (depends on 1)

The phosphor of claim 1, wherein said phosphor exhibits long time persistence (0.25% of initial intensity) from about 2 seconds to about 6 seconds.

### Claim 12 (depends on 1)

The phosphor of claim 1, wherein said phosphor exhibits color coordinates of x from about 0.120 to about 0.140 and y from about 0.770 to about 0.790.

### Claim 13 (depends on 1)

The phosphor of claim 1, wherein said phosphor has a particle size from about 0.01 microns to about 10.0 microns.

### Claim 14 (depends on 1, 10)

A blend comprising the phosphor of claim 1 and 10% to 50% by wt. of a Tb activated rare earth borate.

### Claim 15 (depends on 1, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)

A blend comprising the phosphor of claim 1 and 10 to 25% by weight of Mn activated zinc silicate and 10 to 25% of Tb activated rare earth borate.

### Claim 16 (depends on 1, 10)

A blend comprising the phosphor of claim 1 and 10% to 50% by wt. of Tb and Ce activated rare earth phosphate.

### Claim 17 (depends on 1, 10)

A blend comprising the phosphor of claim 1 and 10% to 50% by wt. of Tb and Ce activated magnesium aluminate.

### Claim 18

A method of producing a green emitting Mn and alkali metal activated lanthanide aluminate phosphor having the empirical formula:
Ln(2-x-y)B22O36:Mnx.Ay
wherein:
Ln is a combination of La, Y, Gd, and Tb, wherein La is: 0.57≦La≦1.782; Y is: 0≦Y ≦0.19; Gd is: 0.198≦Gd≦0.95; and Tb is: 0≦Tb≦0.19;
A is selected from the group consisting of: Li, Na, K and a combination thereof;
B is selected from the group consisting of: Al and a combination of Al and Ga;
x is from about 0.01 to about 0.1; and
y is from about 0.01 to about 0.1;
wherein said method comprises the steps of:
mixing a source of an alkali metal, a source of manganese, a source of lanthanide and a source of aluminum in an acid medium to form dilute aqueous solution;
removing at least a portion of water from said dilute aqueous solution to form a gel;
heating said gel at a temperature sufficient to remove excess water thereby converting said gel into a gel powder; and
thermally decomposing said gel powder at a temperature and for a length of time sufficient to produce said phosphor.

### Claim 19 (depends on 18)

The method of claim 18, wherein said source of alkali metal is an alkali metal salt, said source of lanthanide is a lanthanide salt, said source of manganese is manganese salt, and said source of aluminum is an organic precursor providing aluminum.

### Claim 20 (depends on 19)

The method of claim 19, wherein said alkali metal salt is selected from the group consisting of: alkali halides, alkali nitrate, alkali carbonate, alkali hydroxide, and mixtures thereof; said lanthanide salt is selected from the group consisting of: lanthanide oxalate, lanthanide nitrate, lanthanide oxide, and mixtures thereof; said manganese salt is selected from manganese halides, manganese nitrate, manganese carbonate, manganese hydroxide, and mixtures thereof; and said organic precursor providing aluminum is selected from the group consisting of: aluminum isopropoxide, aluminum s-butoxide, and mixtures thereof.

### Claim 21 (depends on 18)

The method of claim 18, wherein said gel is dried to form said gel powder prior to thermal decomposition.

### Claim 22 (depends on 18)

The method of claim 18, wherein said gel is vacuum dried to form said gel powder as an aerogel prior to thermal decomposition.

### Claim 23 (depends on 18)

The method of claim 18, wherein said gel is spray dried to form said gel powder prior to thermal decomposition.

### Claim 24 (depends on 18)

The method of claim 18, wherein said gel is thermally decomposed in an open atmosphere at a temperature from abut 1000° C. to about 1400° C. and then at a temperature from about 1000° C. to about 1300° C. in forming gas.

### Claim 25 (depends on 18)

The method of claim 18, wherein said phosphor has a particle size from about 0.01 microns to about 10.0 microns.

### Claim 26 (depends on 18)

The method of claim 18, wherein said phosphor exhibits a relative intensity (AU) at 147 nm excitation from about 90 to about 100 and relative intensity (AU) at 173 nm excitation from about 90 to about 105 with half width from about 23 to about 25 nm.

### Claim 27 (depends on 18)

The method of claim 18, wherein said phosphor exhibits short time persistence (10% of initial intensity) from about 7 ms to about 10 ms.

### Claim 28 (depends on 18)

The method of claim 18, wherein said phosphor exhibits color coordinates of x from about 0.120 to about 0.140 and y from about 0.770 to about 0.790.

### Claim 29 (depends on 18)

The method of claim 18, wherein said source of lanthanide is lanthanide oxalate; said source of manganese halide is manganese fluoride; said source of alkali metal is alkali fluoride; and said source of aluminum is aluminum oxide.

### Claim 30 (depends on 18)

The method of claim 18, wherein said powder is thermally decomposed in an open atmosphere at 1400° C. and then at a temperature equal 1200° C. in a forming gas contains 4.0 to 5.0% of H2 and remaining N2.

### Claim 31 (depends on 18)

The method of claim 18, wherein said gel is dried to form a xerogel and said xero-gel is crushed to form a powder prior to thermal decomposition.

### Claim 32 (depends on 18)

The method of claim 18, wherein said gel is vacuum dried to form an aero-gel, and said aero-gel is crushed to form a powder prior to thermal decomposition.

### Claim 33 (depends on 18)

The method of claim 18, wherein said gel is spray dried to form a gel powder prior to thermal decomposition.

### Claim 34 (depends on 18)

The method of claim 18, wherein said gel is sprayed ultrasonically and dried to form a gel powder prior to thermal decomposition.

### Claim 35 (depends on 18)

The method of claim 18, wherein said phosphor has a particle size in the range of 0.01 to 10.0 microns.

### Claim 36 (depends on 31)

The method of claim 31, wherein said powder has a particle size in the range of 0.05 to 5.0 microns.

### Claim 37 (depends on 32)

The method of claim 32, wherein said powder has a particle size in the range of 0.05 to 5.0 microns.

### Claim 38 (depends on 33)

The method of claim 33, wherein said powder has a particle size in the range of 0.01 to 3.0 microns.

### Claim 39 (depends on 34)

The method of claim 34, wherein said powder has a particle size in the range of 0.01 to 0.02 microns.

### Claim 40

A phosphor material for a plasma display panel comprising a composition represented by the formula:
Ln(2-x-y)B22O36:MnxAy
wherein:
Ln is a combination of La, Y, Gd, and Tb, wherein La is: 0.57≦La≦1.782; Y is: 0≦Y≦0.19; Gd is: 0.198≦Gd≦0.95; and Tb is: 0≦Tb≦0.19;
A is selected from the group consisting of: Li, Na, K and a combination thereof;
B is selected from the group consisting of: Al and a combination of Al and Ga;
x is from about 0.01 to about 0.1; and
y is from about 0.01 to about 0.1;
which phosphor emits green light when excited by vacuum ultra violet light of wavelength in the range of 100 nm to 200 nm.

### Claim 41

An improved plasma display panel, having a front plate with electrodes, dielectric layer, a thin protecting layer (MgO), a back plate with electrodes, reflective layer, ribs, phosphors, and a plurality of discharge spaces filled with a gas mixture between said front plate and said back plate, wherein said gas mixture comprises 5 to 50% Xe, and 50 to 95% Ne, wherein the improvement comprises:
a plasma display panel which includes a green emitting phosphor material comprising a composition represented by the formula:
Ln(2-x-y)B22O36:MnxAy
wherein:
Ln is a combination of La, Y, Gd, and Tb, wherein La is: 0.57≦La≦1.782; Y is: 0≦Y≦0.19; Gd is: 0.198≦Gd≦0.95; and Tb is: 0≦Tb≦0.19;
A is selected from the group consisting of: Li, Na, K and a combination thereof;
B is selected from the group consisting of: Al and a combination of Al and Ga;
x is from about 0.01 to about 0.1; and
y is from about 0.01 to about 0.1;
which phosphor emits green light when excited by vacuum ultra violet light of wavelength in the range of 100 nm to 200 nm.

### Claim 42

A solvent free method of producing a green emitting Mn and alkali metal activated lanthanide aluminate phosphor having the empirical formula:
Ln(2-x-y)B22O36:MnxAy25
wherein:
Ln is a combination of La, Y, Gd and Tb, wherein La is: 0.57≦La≦1.782; Y is: 0≦y≦0.19; Gd is: 0.198≦Gd≦0.95; and Tb is: 0≦Tb≦0.19;
A is selected from the group consisting of: Li, Na, K and a combination thereof;
B is selected from the group consisting of: Al and a combination of Al and Ga;
x is from about 0.01 to about 0.1; and
y is from about 0.01 to about 0.1;
wherein said method comprises the steps of:
mixing a source of an alkali metal, a source of manganese, a source of lanthanide and a source of aluminum to form a powder mixture; and thermally decomposing said powder mixture at a temperature and for a length of time sufficient to produce said phosphor.

### Claim 43 (depends on 18)

The method of claim 18, wherein said gel is dried to form a xerogel, and said xero-gel is crushed to form a powder prior to thermal decomposition.