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Method for making rare earth oxide coated phosphor

A technology of zinc silicate and phosphor, applied in the field of phosphor, can solve the problems of high complexity, many processing steps, and time-consuming

Inactive Publication Date: 2014-07-02
GENERAL ELECTRIC CO
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, these methods are not always economical due to their costly complexity and / or large and time-consuming processing steps

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example

[0058] The following examples are merely illustrative and should not be construed as limiting the scope of the present invention in any way.

example 1

[0060] Nanoscale yttrium oxide powder (from Inframat) having a particle size of about 40 to 50 nm was dispersed in 50 ml of water to form a slurry. Three samples (Samples 1, 2 and 3), ie, 20wt%, 30wt% and 40wt% nanoscale yttrium oxide slurries were prepared. These slurries were sonicated for about 2 hours. Each portion of the slurry was then mixed with 5 grams of manganese-doped zinc orthosilicate powder (average particle size about 9 microns) separately, by stirring using a magnetic stirrer. Each mixture was then wet milled for about 3 hours and dried in an oven at 100°C. These mixtures were then placed in an oven (about 400°C) overnight. Finally the dry mixture was burned at about 700°C for about 3 hours in a 1% nitrogen atmosphere. SEM images of these samples show yttria-coated zinc silicate particles.

example 2

[0062] Yttrium acetate was dissolved in 25 ml of water to prepare two samples (Samples 4 and 5), ie, 25% by weight and 30% by weight solutions of yttrium acetate. The solution was heated to completely dissolve the yttrium acetate in the water. Each portion of the yttrium acetate solution was slowly added to 5 grams of manganese-doped zinc orthosilicate powder (particle size about 5 microns) placed in a beaker. Submerge the zinc silicate completely in the acetate solution. The mixture was stirred with a magnetic stirrer for about 2 hours. The mixture was then heated to evaporate the water and placed in an oven (about 400°C) overnight. The two samples were then burned at about 700°C under 1% nitrogen for 3 hours to convert the yttrium acetate to yttrium oxide. SEM images of these samples show yttria-coated zinc silicate particles.

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PUM

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Abstract

A method for making coated zinc silicate phosphor, the method includes the steps of combining a zinc silicate with a rare earth compound under aqueous conditions and removing the water from a product of the combination to form a powder. The powder is fired to form a coated zinc silicate phosphor.

Description

technical field [0001] The present invention generally relates to a method for making a rare earth oxide coated phosphor. More specifically, the present invention relates to a method for making modified zinc silicate phosphors coated with rare earth oxides for use in fluorescent lamps. Background technique [0002] Fluorescent lamps are low-pressure mercury arc discharge devices that have electrodes at each end of an elongated glass envelope and contain a phosphor coating on the inner surface of the glass envelope. With the increase of use time, the brightness of this lamp will gradually decrease. During lamp operation, there are various factors that cause the brightness to decrease. These factors include darkening of the lamp, aging of the fluorescent material, and reduction in the luminous efficacy of the fluorescent material due to adsorption (reaction) of mercury. The ability of such lamps to resist reduction in brightness is commonly referred to as lumen maintenance ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C09K11/59C09K11/02
CPCC09K11/7701C09K11/025C09K11/595
Inventor P.K.纳马尔瓦A.M.斯里瓦斯塔瓦S.阿德帕利D.G.波罗布W.W.比尔斯W.E.科亨
Owner GENERAL ELECTRIC CO