Ceramics Composite Stabilizing Ce Distribution for LED Emission
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Solution Overview
Problem
Existing ceramics composites for white or color LED illumination suffer from inhomogeneous wavelength conversion and chromaticity variation due to Ce evaporation during production, leading to unstable light emission.
Innovation Solution
A ceramics composite with a matrix phase of Al2O3 or Al2O3 incorporating Sc2O3 or Ga2O3, a main phosphor phase of A3B5O12:Ce, and a CeAl11O18 phase mixed within, which maintains homogeneous Ce distribution and emission intensity by compensating for evaporated Ce and controlling the thickness and volume percentage of the CeAl11O18 phase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Ce is used as a phosphor dopant in YAG-based ceramics, then emission intensity is improved, but Ce evaporates during firing causing chromaticity variation and inhomogeneous wavelength conversion
Solution Approach 1:
The patent introduces a silicate glass phase as an intermediary substance that acts as a Ce reservoir during firing. This glass phase has lower melting point and higher Ce solubility compared to the YAG ceramic matrix, allowing it to absorb excess Ce and prevent its evaporation, thereby maintaining chromaticity uniformity while preserving emission intensity
Solution Approach 2:
The patent changes the chemical environment parameters by introducing a silicate glass phase with different composition and properties than the YAG ceramic matrix. This creates a dual-phase system where the glass phase provides a different chemical potential for Ce, preventing evaporation and enabling homogeneous Ce distribution throughout the composite
2Productivity
If Ce concentration is increased to improve emission intensity, then wavelength conversion efficiency improves, but Ce evaporation becomes more severe causing greater chromaticity variation
Solution Approach 1:
The silicate glass phase serves as an intermediary Ce reservoir that can accommodate high Ce concentrations without evaporation. The glass phase absorbs excess Ce atoms during firing, maintaining a stable Ce concentration in the YAG phosphor particles and ensuring uniform emission distribution even at high overall Ce levels
Solution Approach 2:
The patent creates a composite material system combining YAG ceramic particles with silicate glass binder. This composite structure allows the Ce to be distributed between the YAG phosphor phase and the glass matrix, with the glass phase acting as a stabilizing medium that prevents Ce loss during high-temperature processing
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 solution achieves stable, homogeneous wavelength conversion and emission distribution, reducing chromaticity variation and enhancing emission intensity, resulting in consistent white or color LED light emission without color unevenness.
Implementation Method 1
Ce is prone to evaporate during firing at the time of production
Implementation Method 2
a CeAl11O18 phase which is mixed only in the main phosphor phase and is present in higher density with a prescribed thickness at an outer peripheral part than at an inner part of the main phosphor phase
Implementation Method 3
a main phosphor phase formed in the matrix phase and including a substance represented by a general formula A3B5O12:Ce
Data Source
AI summary
The present invention relates to a ceramics composite including: a matrix phase including Al2O3 or a substance in which one selected from Sc2O3 and Ga2O3 is incorporated into Al2O3; a main phosphor phase formed in the matrix phase and including a substance represented by a general formula A3B5O12:Ce in which A is at least one selected from Y, Gd, Tb, Yb and Lu and B is at least one selected from Al, Ga and Sc; and a CeAl11O18 phase mixed in the matrix phase and the main phosphor phase.