Beta-Sialon Fluorescent Material Particle Distribution Control
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Solution Overview
Problem
Conventional β-Sialon fluorescent materials experience a decrease in luminescence intensity due to small particle diameters, leading to reduced brightness in white LEDs, as smaller particles result in increased scattered light and reduced absorption of excitation light, which degrades dispersion properties and causes discoloration.
Innovation Solution
A β-Sialon fluorescent material with a specific particle diameter distribution, where the cumulative 10% diameter (D10) falls within 7 μm to 20 μm and 90% diameter (D90) within 50 μm to 90 μm, is achieved by adjusting heating conditions during production, including multiple heating steps and deagglomeration, to enhance fluorescence intensity while maintaining good dispersion properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the particle diameter of β-Sialon fluorescent material is reduced, then the dispersion properties are improved, but the luminescence intensity decreases due to increased scattered light and reduced absorption of excitation light
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle diameter distribution parameters (D10 and D90) of the β-Sialon fluorescent material. By setting D10 within 7-20 μm and D90 within 50-90 μm, the invention optimizes the balance between dispersion properties and luminescence intensity, resolving the contradiction between these two features through quantitative parameter specification.
2Illumination intensity
If the particle diameter of β-Sialon fluorescent material is increased, then the luminescence intensity is improved, but the dispersion properties deteriorate and discoloration occurs
Solution Approach 1:
The patent resolves this contradiction by establishing specific parameter ranges for particle diameter distribution. By controlling D10 to 7-20 μm and D90 to 50-90 μm, the invention achieves optimal luminescence intensity while preventing aggregation and discoloration, thus maintaining good dispersion properties even with larger particles.
3Ease of manufacture
If conventional heating conditions are used, then the production process is simple, but the particle diameter distribution is not optimized, resulting in decreased luminescence intensity
Solution Approach 1:
The patent applies parameter changes to heating conditions, specifically controlling the heating temperature between 1700-2100°C and heating time between 6-24 hours. These optimized parameters produce the desired particle diameter distribution (D10: 7-20 μm, D90: 50-90 μm) that maximizes luminescence intensity while maintaining manufacturing feasibility.
4Duration of action of stationary object
If the fluorescent material is exposed to excitation source for extended periods, then the operating life is extended, but the brightness decreases due to degradation
Solution Approach 1:
The patent applies beforehand cushioning by optimizing the particle diameter distribution before the fluorescent material is put into service. The controlled particle size (D10: 7-20 μm, D90: 50-90 μm) prevents aggregation and reduces stress concentration, thereby cushioning against degradation during extended operation and maintaining brightness stability over time.
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 resulting fluorescent material exhibits stable and high fluorescence intensity with minimal discoloration, maintaining brightness and long operating life, even at high temperatures, suitable for various illuminators including white LEDs.
Implementation Method 1
a fluorescent material comprising a β-Sialon (SiAlON), which emits visible light when excited by ultraviolet or blue light
Implementation Method 2
heating conditions during production, including multiple heating steps
Data Source
AI summary
A fluorescent material comprising: a β-Sialon expressed by the general formula Si6-ZAlZOZN8-Z as a host material; and Eu dissolved in solid solution as a luminescence center, is a powder which, when measured by the laser diffraction scattering method, gives particle diameter distribution in which cumulative 10% diameter (D10) falls within the 7 μm to 20 μm range and 90% diameter (D90) within the 50 μm to 90 μm range, and can be used as a fluorescent material low in luminescence intensity degradation ideal for illuminators. This fluorescent material can be produced by subjecting a raw powder, which is obtained by mixing a silicon nitride powder, aluminum nitride powder, and aluminum-containing or Eu-containing compound as required, to heating at 1850° C. to 2050° C. for 9 hours or longer in a nitrogen or nonoxidizing atmosphere.