Eu-Activated β-Sialon Fluorescent Substance for High-Efficiency White LEDs
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Solution Overview
Problem
Conventional fluorescent substances with Eu-activated β-sialons have poor luminous efficiency, making them difficult to use effectively in light-emitting devices due to reduced luminosity and color shifting at higher temperatures and under blue or UV excitation.
Innovation Solution
A fluorescent substance with Eu-activated β-sialon as the main constituent, characterized by a spin density of 2.0×10^17/g or less, is developed, which emits green light efficiently when excited by UV to visible light, and is produced through heat treatment and acid treatment to reduce crystal defect density, enhancing luminous efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional fluorescent substances with Eu-activated β-sialons are used, then green light emission is achieved, but luminous efficiency is poor and luminosity reduces at higher temperatures
Solution Approach 1:
The patent changes the chemical composition parameters of the β-sialon crystal structure by controlling the substitution of Si and N atoms with Al and O atoms respectively. By adjusting the compositional ratio within the formula Si6-zAlzOzN8-z (where z is 0-4.2), the patent optimizes both the luminous efficiency and thermal stability, resolving the contradiction between achieving green light emission and maintaining performance at high temperatures.
2Power
If conventional fluorescent substances are used with blue LED or UV LED excitation, then light wavelength conversion is achieved, but degradation occurs due to prolonged exposure
Solution Approach 1:
The patent creates a composite fluorescent material by incorporating Eu2+ activator ions into the β-sialon crystal matrix. This composite structure combines the high stability of the β-sialon host material with the efficient green light emission of Eu2+, achieving both high power conversion efficiency and improved reliability under prolonged blue LED or UV LED excitation.
3Measurement precision
If Eu-activated β-sialon is used for green light component, then narrow band emission is achieved, but luminosity reduces and color shifts occur
Solution Approach 1:
The patent optimizes the compositional parameters of β-sialon (controlling the z value in Si6-zAlzOzN8-z) and the Eu2+ doping concentration to achieve the optimal balance between emission spectrum sharpness and luminosity. By precisely controlling these parameters, the patent maintains narrow band green light emission while preventing luminosity reduction and color shifting.
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 fluorescent substance achieves high luminous efficiency and thermal stability, maintaining luminosity and color consistency even at high temperatures, suitable for use in white LEDs and other light-emitting devices.
Implementation Method 1
Eu-activated β-sialons have similar fluorescent properties... upon excitation by UV to blue light, emits green light
Implementation Method 2
produced through heat treatment and acid treatment to reduce crystal defect density
Data Source
AI summary
Offered is a fluorescent substance consisting of Eu-activated β-sialon and capable of enhancing the brightness of a light emitting device such as a white LED using blue or ultraviolet light as a light source. The fluorescent substance has as its main constituent a β-sialon represented by the general formula Si6-zAlzOzN8-z and containing Eu, wherein the spin density is 2.0×1017/g or less as measured by electron spin resonance spectroscopy corresponding to an absorption of g=2.00±0.02 at 25° C. In the above fluorescent substance, it is preferable that lattice constant a of the β-sialon be 0.7608-0.7620 nm, the lattice constant c be 0.2908-0.2920 nm, and the Eu content be 0.1-3 mass %.