Zinc silicate phosphor particles and method for making them

Claim 2

An improved zinc silicate phosphor comprising particles with an inner core of silicon and oxygen rich material, an intermediate region rich in manganese oxides, and an outer portion rich in zinc and oxygen.

Claim 3

A phosphor in accordance with claim 1 wherein said intermediate region contains magnesium and arsenic.

Claim 4

A phosphor in accordance with claim 2 wherein said inner core is rich in silicon dioxide, said intermediate region is rich in manganese, magnesium, arsenic acid oxygen, and said outer portion is rich in zinc and oxygen.

Claim 5

A phosphor in accordance with claims 1, 2 or 3 wherein the combined composition of said inner core, said intermediate region and said outer portion of the phosphor particles comprises compounds in ratios in accordance with the ranges listed as follows: ZnO: 2 moles SiO 2 : 1.60-1.65 moles MgO: 0-0.11 moles MnO: 0.006-0.014 moles As 2 O 3 : 285-1120 parts per million.

Claim 6

A phosphor in accordance with claims 1, 2 or 3 wherein the combined composition of said inner core, said intermediate region and said outer portion of the phosphor particles comprises compounds in ratios in accordance with the ranges listed below: ZnO: 2 moles SiO 2 : 1.1-1.75 moles MgO: 0-0.11 moles MnO: 0.0025-0.02 moles As 2 O 3 : 0-2000 parts per million.

Claim 7

A phosphor in accordance with claims 1, 2 or 3 wherein the combined composition of said inner core, said intermediate region and said outer portion of the phosphor particles includes the components in the ratios indicated: ZnO: 1 SiO 2 : 0.55 to 0.875 MgO: 0 to 0.06 MnO: 0.001 to 0.01 As 2 O 3 : 0-2000 parts per million.

Claim 8

A phosphor in accordance with claims 1, 2 or 3 wherein the combined composition of said inner core, said intermediate region and said outer portion of the phosphor particles includes the components in the ratios indicated: ZnO: 1 SiO 2 : 0.8-0.83 MgO: 0-0.06 MnO: 0.003 to 0.007 As 2 O 3 : 285-1120 parts per million.

Claim 9

An improved zinc silicate phosphor comprising particles with an inner core of silicon and oxygen rich material, an intermediate region rich in manganese oxides, and an outer portion rich in zinc and oxygen, said phosphor having been a product made by the process of: (a) providing particles of silicic acid to sizes on the order of one micrometer and larger, (b) mixing said silicic acid particles in an aqueous solution of Mn, Mg and As cations and highly active anions, (c) adding zinc oxide particles to the result of step (b), drying, and (d) firing the product of step (c) whereby a reacted oxide product is produced.

Claim 10

An improved zinc silicate phosphor comprising particles with an inner core of silicon and oxygen rich material, an intermediate region rich in manganese oxides, and an outer portion rich in zinc and oxygen, said phosphor having been a product made by the process of: (a) providing particles of silicic acid to sizes on the order of one micrometer and larger, (b) mixing said silicic acid particles in an aqueous solution of Mn, Mg and As cations and highly active anions, (c) adding zinc oxide particles to the result of step (b), drying, and (d) firing the product of step (c) whereby a reacted oxide product is produced.

Claim 11

A phosphor in accordance with claim 8 wherein said solution in step (b) includes NH 4 OH.

Claim 12

A phosphor in accordance with claim 8 wherein the product of step (b) is oxidized to form a precipitate containing Mn to coat the exterior surface of said silicic acid particles prior to step (c).

Claim 13

A phosphor in accordance with claim 8 wherein particles of zinc oxide are applied to provide a coating on said particles in step (c), whereby firing of said particles with said coating inhibits sintering of said particles together during firing in step (d).

Claim 14

A phosphor in accordance with claim 8 wherein particles of zinc oxide an order of magnitude smaller than said particles of silicic acid are applied to said particles of silicic acid to provide a coating on said particles of step (b) in step (c), whereby firing of said particles with said coating inhibits sintering of said particles together during firing in step (d).

Claim 15

A phosphor in accordance with claim 8 wherein the product of step (b) is oxidized to form a precipitate of Mn 2 O 3 .xH 2 O to coat the exterior surface of said silicic acid particles prior to step (c).

Claim 16

A phosphor in accordance with claim 8 wherein said silicic acid particles are in the size range between about 0.7 micrometer and 10 micrometers, said solution in step (b) comprises MnSO 4 .H 2 O, As 2 O 3 , HNO 3 and magnesium with an anion, and said firing in step (d) being performed for between about 6 and 36 minutes at a temperature on the order of 1180° C.

Claim 17

A phosphor in accordance with claim 8 wherein the atmosphere empolyed in step (d) comprises wet nitrogen gas.

Claim 18

A phosphor in accordance with claim 8 wherein said aqueous solution in step (b) comprises a solution A n from the table which follows: ______________________________________ SOLUTION A.sub.n Quantities Components A.sub.1 A.sub.2 A.sub.3 A.sub.4 ______________________________________ H.sub.2 O (cc) 13.3 13.3 13.3 13.3 Mg Acetate (g) 0.79 0 0.79 0 Mg (NO.sub.3).sub.2.6H.sub.2 O (g) 0 1.0 0 0 NH.sub.4 OH (cc) 1.0 1.0 1.0 1.0 As.sub.2 O.sub.3 (Stir 2 hrs.) 0.00073 0.00073 0.0002 0.0002 (g) HNO.sub.3 (cc) 1.0 1.0 1.0 1.0 MnSO.sub.4.H.sub.2 O (g) 0.0324 0.0324 0.0816 0.0816 Stir (hrs.) 2 2 2 2 ______________________________________

Claim 19

A method in accordance with claim 8 wherein said aqueous solution in step (b) comprises a solution A n from the table which follows: ______________________________________ SOLUTION A.sub.n Quantities Components A.sub.1 A.sub.2 A.sub.3 A.sub.4 ______________________________________ H.sub.2 O (cc) 13.3 13.3 13.3 13.3 Mg Acetate (g) 0.79 0 0.79 0 Mg (NO.sub.3).sub.2.6H.sub.2 O (g) 0 1.0 0 0 NH.sub.4 OH (cc) 1.0 1.0 1.0 1.0 As.sub.2 O.sub.3 (Stir 2 hrs.) 0.00073 0.00073 0.0002 0.0002 (g) HNO.sub.3 (cc) 1.0 1.0 1.0 1.0 MnSO.sub.4.H.sub.2 O (g) 0.0324 0.0324 0.0816 0.0816 Stir (hrs.) 2 2 2 2 ______________________________________ and the product of step (b) is oxidized to form a precipitate containing Mn with addition of solution B which follows: ______________________________________ SOLUTION B ______________________________________ NH.sub.4 OH (cc) 3.5 H.sub.2 O.sub.2 (cc) 1.5 ______________________________________