Eu2+ Doped Beta-Sialon Phosphor Wavelength Tuning
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Solution Overview
Problem
Conventional Eu 2+ doped β-Sialon phosphors face challenges in maintaining luminescence intensity and efficiency when the peak fluorescence wavelength falls outside the 540 to 545 nm range, with significant decline in luminescence intensity and difficulty in adjusting luminescence properties due to composition and Eu content adjustments.
Innovation Solution
A method of producing Eu 2+ doped β-Sialon with a modified z value range (0.3 to 1.5) and increased Al 2 O 3 ratio, incorporating β-Sialon as a raw material additive to suppress interparticle sintering and enhance crystalline phase purity, allowing for longer wavelength luminescence while maintaining high luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the z value is adjusted to change the peak fluorescence wavelength, then the luminescence wavelength can be shifted, but the luminescence intensity significantly declines
Solution Approach 1:
The patent applies parameter changes by modifying the z value within a specific range (0.24 ≤ z ≤ 4.2) to adjust the peak fluorescence wavelength from 520 nm to 560 nm. Simultaneously, it optimizes the Al content (1.0-5.0 at%) and Eu content (0.1-2.0 at%) to maintain high luminescence intensity despite wavelength shifts, resolving the contradiction between wavelength adjustment capability and luminescence intensity maintenance
Solution Approach 2:
The patent creates a composite phosphor material by doping Eu 2+ ions into the β-Sialon crystal lattice, forming a solid solution with the formula Si 6-z Al z O z N 8-z :Eu 2+. This composite structure allows independent optimization of the host lattice (for wavelength control via z value) and the dopant concentration (for intensity control), simultaneously achieving both wavelength adjustability and high luminescence intensity
2Illumination intensity
If the Eu content is increased to enhance luminescence intensity, then the brightness improves, but the manufacturing precision and composition control become more difficult
Solution Approach 1:
The patent optimizes the Eu content parameter within the range of 0.1-2.0 at%, identifying this as the optimal balance point where sufficient luminescence intensity is achieved while maintaining manageable manufacturing precision. The patent further refines composition control by specifying narrow ranges for z value (0.24-4.2), Al content (1.0-5.0 at%), and Eu content (0.1-2.0 at%), making the manufacturing process more controllable
Solution Approach 2:
The patent replaces complex post-synthesis adjustment methods with a optimized raw material formulation approach. By pre-calculating and controlling the composition ratios in the starting materials (Si 6-z Al z O z N 8-z :Eu 2+), the patent achieves precise compositional control without requiring complex mechanical or manual adjustment processes during manufacturing
3Ease of manufacture
If the Al content is increased to shift luminescence wavelength, then the peak wavelength changes, but the manufacturing complexity increases
Solution Approach 1:
The patent uses parameter changes by adjusting the Al content (represented by the z parameter in the formula Si 6-z Al z O z N 8-z) to control the peak fluorescence wavelength. By establishing a direct relationship between Al content and wavelength output, the patent simplifies the manufacturing process - manufacturers only need to control the Al content within 1.0-5.0 at% to achieve desired wavelength shifts, reducing overall manufacturing complexity
Solution Approach 2:
The patent makes the Al content parameter serve multiple functions: it simultaneously controls the luminescence wavelength (by adjusting z value) and maintains crystal structure stability (by keeping Al content within 1.0-5.0 at%). This multi-functionality reduces the need for separate adjustment mechanisms, thereby simplifying the manufacturing process
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 method achieves a peak fluorescence wavelength of 545 to 560 nm with a half-value breadth of 55 nm or longer and external quantum efficiency of 45% or higher, enabling efficient green-to-yellow light emission suitable for various light-emitting devices.
Implementation Method 1
divalent europium (Eu) ion doped β-Sialon which contains divalent europium (Eu) ions in a form of solid solution, in particular, is coming into practical use as a phosphor useful for white LED because it is excited by light in wide wavelength range from ultraviolet to blue light and emits green light
Implementation Method 2
heating to manufacture Eu 2+ doped β-Sialon phosphor
Data Source
Figure 1~2
Figure 3~4
AI summary
β-Sialon comprising Eu2+ that is present in a solid solution form in β-sialon represented by Si6-zAlzOzN µm [wherein z is 0.3-1.5], which shows, when excited with light of 450 nm in wavelength, a peak wavelength of fluorescent spectrum of 545-560 nm, a half-value breadth of 55 nm or greater, and an external quantum efficiency of 45% or greater. The β-sialon can be produced by blending at least one kind of oxide selected from aluminum oxide and silicon oxide with silicon nitride and aluminum nitride in such a manner as to give z of 0.3-1.5, further adding thereto a europium compound and a β-sialon powder having an average particle diameter of 5 µm or greater and an average degree of circularity of 0.7 or greater, each in a definite amount, and baking the mixture.