Ce-Doped Phosphor Powder With Controlled Particle Distribution
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Solution Overview
Problem
The phosphor disclosed in Patent Document 1 has room for improvement in terms of conversion efficiency of blue light, specifically in fluorescence peak intensity, internal quantum efficiency, and external quantum efficiency.
Innovation Solution
A phosphor powder with phosphor particles represented by the general formula Mx(Si, Al)2(N, O)3±y, where M is Li and one or more alkaline earth metal elements, with a Si/Al atomic ratio of 1.5 to 6, O/N atomic ratio of 0 to 0.1, 5 to 50 mol % Li, and 0.5 to 10 mol % Ce, and a particle size distribution index (D90-D10)/D50 of 0.7 to 1.1, is developed. This phosphor powder is produced using suitable production methods and conditions, including classification and pulverization, to enhance blue light conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the phosphor composition is modified to improve blue light conversion efficiency, then fluorescence peak intensity and quantum efficiency are improved, but particle size distribution control becomes more difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Si/Al atomic ratio (1.05-2.0) and O/N atomic ratio (0-0.05) within the phosphor chemical formula Mx(Si, Al)2(N, O)3±y. These compositional parameter adjustments optimize the crystal structure to enhance blue light absorption and fluorescence emission, thereby improving conversion efficiency while maintaining manufacturability through defined compositional ranges.
Solution Approach 2:
The patent employs preliminary action by implementing a classification process during manufacturing to pre-sort phosphor particles into specific size ranges before final product formation. This preliminary classification ensures that the particle size distribution parameter (D90-D10)/D50 remains within 0.6-1.2, optimizing light emission efficiency without requiring complex post-processing and maintaining manufacturing precision.
2Productivity
If the phosphor particle size distribution is optimized to improve light emission efficiency, then conversion efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The patent implements preliminary classification during the manufacturing process to pre-establish the desired particle size distribution characterized by (D90-D10)/D50 = 0.6-1.2. This preliminary size control is integrated into the production flow rather than added as a separate complex post-processing step, thereby improving light emission efficiency while minimizing manufacturing process complexity.
Solution Approach 2:
The patent utilizes parameter changes by controlling synthesis conditions (temperature, pressure, reaction time) to directly produce phosphor particles with optimized size distribution. By adjusting these synthesis parameters, the particle size distribution is controlled in-situ during manufacturing, improving light emission efficiency without requiring additional complex classification equipment or processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The phosphor powder exhibits high internal quantum efficiency and excellent blue light conversion efficiency, with a sharp particle size distribution that improves light emission efficiency and durability, making it suitable for light-emitting devices and image display applications.
Implementation Method 1
a phosphor is used as a wavelength conversion material for obtaining white light from blue light emitted from a blue LED
Implementation Method 2
a phosphor which is represented by a general formula Mx(Si, Al)2(N, O)3±y... in which the phosphor powder includes phosphor particles... having a great fluorescence peak intensity when a phosphor is irradiated with blue light
Data Source
AI summary
A phosphor powder including phosphor particles of a phosphor represented by a general formula Mx(Si, Al)2(N, O)3±y and in which a part of M is substituted with a Ce element, the phosphor powder includes phosphor particles in which a Si/AI atomic ratio is equal to or more than 1.5 and equal to or less than 6, an O/N atomic ratio is equal to or more than 0 and equal to or less than 0.1, 5 to 50 mol % of M is Li, and 0.5 to 10 mol % of M is Ce. In a case where a volume-based cumulative 10% particle size, a volume-based cumulative 50% particle size, and a volume-based cumulative 90% particle size of this phosphor powder measured by a laser diffraction scattering method are defined as D10, D50, and D90, respectively, (D90-D10)/D50 is equal to or more than 0.7 and equal to or less than 1.1.