Beta-Sialon Phosphor Oxygen Control Luminance Stability
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Solution Overview
Problem
Conventional β-sialon phosphors used in light emitting devices suffer from low luminance and poor thermal and chemical stability, limiting their efficiency and reliability in white light emitting applications.
Innovation Solution
A β-sialon phosphor represented by the formula Si(6-z)AlzOyN(8-z):Re, where 0.018≦x≦0.3, 0.3≦y≦0.75, and 0.42≦z≦1.0, with a rare-earth element Re, is developed, which is synthesized by adjusting oxygen concentration and sintering conditions to enhance crystallinity and luminance, achieving a peak emission wavelength of 500 to 550 nm and a particle size of 5 to 20 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional β-sialon phosphors are used, then the phosphor can be manufactured with existing processes, but the luminance is low and thermal/chemical stability is poor
Solution Approach 1:
The patent applies parameter changes by precisely controlling the oxygen concentration (y parameter) in the β-sialon phosphor composition Si(6-z)AlzOyN(8-z):Re. By optimizing the oxygen content within specific ranges (0.3≦y≦0.75), the patent simultaneously improves luminance output and enhances thermal/chemical stability, resolving the contradiction between brightness and reliability through compositional parameter optimization
Solution Approach 2:
The patent creates a composite phosphor material by incorporating rare-earth elements (Re) into the β-sialon host lattice. This composite structure combines the structural stability of β-sialon with the luminescent properties of rare-earth elements, achieving both high luminance and improved thermal/chemical stability that neither component could achieve alone
2Illumination intensity
If the phosphor is excited by high energy sources (UV rays, electron beams), then the phosphor can emit light, but the phosphor deforms and luminance decreases
Solution Approach 1:
The patent uses parameter changes by optimizing the crystal structure composition through controlled oxygen concentration (y parameter) and stoichiometric ratios. This creates a more stable crystal lattice that can withstand high-energy excitation without deformation, maintaining luminance over time while still enabling efficient light emission from UV and blue light excitation sources
3Illumination intensity
If aluminum concentration is increased to improve luminance, then the luminance increases, but the particle size grows larger which may affect performance
Solution Approach 1:
The patent applies parameter changes by independently optimizing multiple compositional parameters simultaneously - specifically the aluminum concentration (z parameter) and oxygen concentration (y parameter). By coordinating these parameters within specific ranges (0.42≦z≦1.0 and 0.3≦y≦0.75), the patent achieves high luminance while controlling particle size growth, preventing the trade-off between brightness and particle dimensions
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 improved β-sialon phosphor exhibits increased luminance by 12.5% or higher, maintaining high thermal and chemical stability, and is effective in green light emitting devices with controlled particle size, enhancing light emitting efficiency and reliability.
Implementation Method 1
sintering the mixture at a high temperature in a nitrogen atmosphere
Implementation Method 2
The oxygen concentration is adjusted by oxidizing the mixture
Implementation Method 3
the phosphor is excited by an excitation source having high energy, for example, vacuum ultraviolet rays, ultraviolet rays, electron beams, and blue light
Data Source
AI summary
According to one example of the present application, a phosphor has the following composition formula (1): [composition formula 1] Si(6-z)AlzOyN(8-z):Rex, where x, y and z are 0.018≦x≦0.3, 0.3≦y≦0.75, 0.42≦z≦1.0, respectively, and Re is a rare earth element. Therefore, even when the aluminum concentration is 0.42 mol to 1.0 mol, a sialon phosphor of the present application exhibits high luminance and has a particle size D50 varying between 5 to 20 μm. In addition, a method for preparing a phosphor according to one example of the present application involves adjusting the oxygen concentration to ensure the superior crystallinity of the phosphor and thus improve the luminance thereof.