Gte Products Corporation

Michael A Krebs

Charles F Chenot

Leslie F Gray

A europium activated strontium tetraborate UV emitting phosphor is disclosed having a weight composition of from about 34.72% to about 35.80 strontium %, from about 17.66% to about 17.78 boron %, from about 0.37% to about 1.86% europium, and the balance oxygen. The phosphor has essentially elongated prism-like particles with the europium relatively uniformly distributed throughout the balance of the phosphor and with the particle size distribution being characterized by the 50% size being in the range of from about 7 micrometers to about 12 micrometers as determined by Coulter Counter measurement and with less than about 12% by weight of the particles having a particle size of greater than about 16 micrometers as determined by Coulter Counter measurement. The process for making the phosphor is disclosed which involves forming a mixture of strontium carbonate and europium carbonate in an aqueous solution of boric acid at a temperature of at least about 70.degree. C. with the mole ratio of SrCO.sub.3 to H.sub.3 BO.sub.3 being from about 1:4 to 1:4.5 and the Eu.sub.2 O.sub.3 content being from about 0.003 to 0.015 moles. The mixture is digested at at least about 90.degree. C. for a sufficient time to form a solid precipitate comprising a strontium borate hydrate intermediate and a liquor, followed by separating the solid from the liquor, drying the solid and firing the solid in an atmosphere of 0.3%, to 3.0% by volume hydroen and the balance nitrogen at at least about 800.degree. C. for a sufficient time to produce the phosphor.

Europium activated strontium tetraborate UV phosphors

A europium activated strontium tetraborate UV emitting phosphor is disclosed having a weight composition of from about 34.72% to about 35.80 strontium %, from about 17.66% to about 17.78 boron %, from about 0.37% to about 1.86% europium, and the balance oxygen. The phosphor has essentially elongated prism-like particles with the europium relatively uniformly distributed throughout the balance of the phosphor and with the particle size distribution being characterized by the 50% size being in the range of from about 7 micrometers to about 12 micrometers as determined by Coulter Counter measurement and with less than about 12% by weight of the particles having a particle size of greater than about 16 micrometers as determined by Coulter Counter measurement. The process for making the phosphor is disclosed which involves forming a mixture of strontium oxide and europium carbonate in an aqueous solution of boric acid at a temperature of at least about 70.degree. C. with the mole ratio of SrCO.sub.3 to H.sub.3 BO.sub.3 being from about 1:4 to 1:4.5 and the Eu.sub.2 O.sub.3 content being from about 0.003 to 0.015 moles. The mixture is digested at at least about 90.degree. C. for a sufficient time to form a solid precipitate comprising a strontium borate hydrate intermediate and a liquor, followed by separating the solid from the liquor, drying the solid and firing the solid in an atmosphere of 0.3% to 3.0% by volume hydrogen and the balance nitrogen at at least about 800.degree. C. for a sufficient time to produce the phosphor.

Process for producing europium activated stronium tetraborate UV phosphor

A process is disclosed for producing a europium activated strontium borate phosphor having a strontium containing coating. The process involves washing a europium activated strontium borate phosphor with a solution of strontium hydroxide to produce a first washed phosphor followed by removing the first washed phosphor from the resulting wash solution. The first washed phosphor is washed with a wash solution selected from the group consisting of ammonium fluoride in alcohol, ammonium bifluoride in alcohol, and a strontium salt in ammonium hydroxide, followed by removing the resulting second washed phosphor from the resulting wash solution. The second washed phosphor is then heated to produce the coated phosphor.

Growing community of inventors

Waverly, NY, United States of America

Michael A Krebs