Beta-sialon Phosphor Particle Size Control for Luminance
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Solution Overview
Problem
Current β-sialon phosphors and light emitting devices require further improvement in luminance to meet increasing demands for heat resistance and durability.
Innovation Solution
A β-sialon phosphor with specific particle size distributions, where D50 is between 7.0 μm and 20.0 μm, and (D50−D10)/D50 is 0.60 or less, is used in conjunction with a light emitting device that includes an LED chip emitting light between 300 nm to 500 nm, and optionally a manganese-solid-dissolved KSF-based phosphor, to enhance luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the particle size of β-sialon phosphor is increased to improve luminance, then light emitting intensity increases, but particle size uniformity deteriorates
Solution Approach 1:
The patent applies parameter changes by optimizing the particle size parameters D50 and (D50-D10)/D50 to specific ranges (D50: 7.0-20.0 μm, (D50-D10)/D50: 0.60 or less). This resolves the contradiction by defining precise parameter boundaries that simultaneously achieve high luminance through adequate particle size while maintaining uniformity through controlled size distribution.
Solution Approach 2:
The patent uses partial action by specifying that only the primary particles (single-crystal particles distinguished by EBSD) need to meet the size criteria, while allowing secondary particles (aggregates of primary particles) to exist. This selective application of size control to the relevant structural unit resolves the contradiction between achieving sufficient luminance and maintaining practical manufacturability.
2Power
If the output of light emitting devices is increased to meet heat resistance and durability demands, then device performance improves, but phosphor stability requirements increase
Solution Approach 1:
The patent employs composite materials by combining β-sialon phosphor with specific particle size characteristics (D50: 7.0-20.0 μm, (D50-D10)/D50: 0.60 or less) to create a phosphor composition that achieves both high output and enhanced stability. The optimized particle size distribution contributes to improved crystallinity and reduced impurities, thereby maintaining reliability under high power operation.
Solution Approach 2:
The patent applies local quality by focusing control on the primary particle level (single-crystal particles) rather than the overall aggregate structure. By controlling the size and distribution of primary particles specifically, the patent achieves improved crystallinity and reduced impurities at the local level, which enhances phosphor stability while allowing high device output.
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 described β-sialon phosphor and light emitting device configuration results in improved luminance by optimizing particle size and distribution, reducing impurities and enhancing crystallinity, leading to increased light emitting intensity and reduced color variations.
Implementation Method 1
A phosphor in which Eu2+ is solid-dissolved in the crystal structure of β-sialon is a phosphor which is excited by ultraviolet to blue light and emits green light at 520 to 550 nm
Data Source
AI summary
A β-sialon phosphor that is a solid solution of europium, in which D50 is 7.0 μm or more and 20.0 μm or less and (D50−D10)/D50 is 0.60 or less, where D50 is a 50% area diameter of primary particles of the β-sialon phosphor, and D10 is a 10% area diameter of the primary particles of the β-sialon phosphor. Primary particles are defined as single-crystal particles distinguished for each crystal orientation by identifying the crystal orientation of individual particles of the β-sialon phosphor by an electron backscatter diffraction image method. D50 and D10 are obtained by image analysis of the cross-sectional area of the primary particles.