Surface-treated fluorescent bodies and process for production of surface-treated fluorescent bodies

Abstract

The present invention aims to provide a surface-treated phosphor having high dispersibility and capable of significantly enhancing moisture resistance without deteriorating the fluorescence properties, and a method for producing the surface-treated phosphor. The surface-treated phosphor includes: a phosphor body; and a surface treatment layer containing at least one specific element selected from elements of the third to sixth groups of the periodic table, and fluorine, the phosphor body having the surface treatment layer on the surface thereof, wherein, when a cross section of the surface treatment layer is subjected to a thickness-wise elemental distribution analysis by a combination of an electron microscopic analysis and an energy-dispersive X-ray element analysis, a peak indicating the maximum content of the specific element appears nearer to the surface than a peak indicating the maximum fluorine content.

Description

technical field [0001] The present invention relates to a surface-treated phosphor having remarkably improved moisture resistance and a method for producing the surface-treated phosphor. Background technique [0002] In recent years, semiconductor light-emitting devices (white LEDs) that emit white light have attracted attention as next-generation power sources due to their low power consumption, high efficiency, environmental friendliness, and long life. [0003] In white LEDs, as a method of producing white light, a method of combining blue light or ultraviolet light LEDs with phosphors (red, yellow, green phosphors, etc.) that can be excited by these lights is generally used. [0004] In addition, silicate phosphors containing alkaline earth metal elements have attracted attention because they can easily realize a wide range of emission wavelengths through composition adjustment, and have high luminous efficiency. Among them, as a representative example, there are (Sr, B...

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Problems solved by technology

[0010] However, since the gas-phase method disclosed in Patent Documents 3 and 4 is difficult to completely disperse the finely powdered phosphor particles, it is difficult to cover the surface of each phosphor particle uniformly and comprehensively in reality, and there is a tendency to cause Issues such as pinholes or uneven coverage

In addition, since the gas phase method is usually carried out at a high temperature of 400°C or higher, there is a problem that the fluorescence characteristics after treatment will be significantly lowered depending on the type of phosphor.

Furthermore, since the device is large, the manufacturing component is improved

[0011] On the other hand, when using the sol-gel method (Patent Documents 5, 6, and 7), which is a liquid phase method, although the degree of freedom in selecting the type of coating is large, the metal alkoxide as the starting material is generally highly reactive. , so it is difficult to control the reaction conditions that initiate the hydrolysis reaction only on the surface of phosphor particles

In addition, the film obtained by the sol-gel method contains organic components such as alkoxy groups remaining due to incomplete hydrolysis and alcohols detached during the hydrolysis reaction, so it is usually difficult to obtain a dense film.

[0012] Furthermore, in the coating method disclosed in Patent Document 5, since the hydrolysis reaction is carried out in the presence of excess ammonia water, most of the raw materials are reacted and consumed in a solution other than the surface of the phosphor particles, and there are problems in reaction efficiency and cost. The problem

Moreover, since the phosphor contains excessive ammonia water, the phosphor may be hydrolyzed and deteriorated during the reaction treatment.

[0013] In the method disclosed in Patent Document 6, although the Si-containing compound as a coating is carried on the surface of phosphor particles in a granular or layered form, practically no improvement in moisture resistance is found.

In addition, the reaction conditions described in the examples of Patent Document 6 hardly cause a coating reaction on the surface of phosphor particles, and even if a part can be covered, there is a problem that it is difficult to effectively block water vapor in the case of particle-like coating.

[0014] The method disclosed in Patent Document 7 requires long-time reaction, precise temperature, and process control, and has problems in effect and composition

[0015] On the other hand, in the neutralization precipitation method disclosed in Patent Document 8, it is actually difficult to deposit the coating in the form of a continuous film on the surface of the phosphor particles.

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