Ceramic Sintered Body Suppressing Chromaticity Variation
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Solution Overview
Problem
Ceramic sintered bodies used in lighting devices with blue LEDs or LDs face issues of reduced light emission intensity and chromaticity variation due to the presence of third components like CeAl11O18, which also affect durability when thickness is reduced to mitigate these issues.
Innovation Solution
A ceramic sintered body comprising alumina (Al2O3) and a compound with the formula M1 3-X M2 X M3 5 O12, where M1 is scandium, yttrium, or lanthanoid elements, M2 is cerium or other lanthanoid elements, and M3 is aluminum or gallium, with specific volume percent, X-ray diffraction intensity ratios, and average grain diameter, to enhance light emission and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a third component (such as CeAl11O18) is added to prevent chromaticity variation, then chromaticity stability is improved, but light emission intensity decreases
Solution Approach 1:
The invention extracts and eliminates the harmful third component (CeAl11O18) from the ceramic sintered body by optimizing the composition formula and sintering conditions. This removal eliminates the light absorption caused by the third component, thereby resolving the contradiction between chromaticity stability and light emission intensity.
Solution Approach 2:
The invention changes the compositional parameters by precisely controlling the ratios of Y, Al, and Ce elements within specific ranges, and adjusts sintering parameters (temperature, atmosphere, time) to prevent the formation of the harmful third component. This parameter optimization allows achieving both chromaticity stability and high light emission intensity.
2Illumination intensity
If the thickness of the fluorescent material is reduced to suppress reduction in light emission intensity, then light emission intensity is improved, but durability deteriorates
Solution Approach 1:
By removing the harmful third component through optimized composition and sintering, the invention eliminates the need to reduce thickness for light emission purposes. This allows maintaining sufficient thickness for durability while achieving high light emission intensity.
Solution Approach 2:
The invention creates an optimized composite ceramic structure with controlled grain size distribution and phase composition, where the matrix phase and fluorescent phase are optimally combined. This composite structure provides both high light emission intensity and sufficient mechanical strength for durability.
3Illumination intensity
If the thickness of the fluorescent material is reduced, then light emission intensity is improved, but mechanical strength decreases
Solution Approach 1:
The elimination of the harmful third component allows maintaining optimal thickness for both light emission and mechanical strength, resolving the contradiction between these two parameters.
Solution Approach 2:
The optimized composite ceramic structure with controlled grain size and phase distribution provides enhanced mechanical strength that allows sufficient thickness while maintaining high light emission intensity.
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 effectively suppresses reductions in light emission intensity and chromaticity variation while improving the durability of the ceramic sintered body, making it suitable for use as a fluorescent material with blue LEDs or LDs.
Implementation Method 1
a fluorescent material composed of a ceramic sintered body prepared by adding cerium (Ce) to yttrium aluminum garnet (YAG) shows yellow fluorescence
Implementation Method 2
since the CeAl11O18 phase present absorbs light, the light emission intensity of the fluorescent material may decrease
Implementation Method 3
the ratio of the intensity of X-ray diffraction from a complex oxide of aluminum (Al) and the M2 to the intensity of X-ray diffraction from the compound in the ceramic sintered body
Data Source
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AI summary
The durability of a ceramic sintered body is improved, and a reduction in its light emission intensity and the occurrence of a chromaticity variation are suppressed. The ceramic sintered body contains alumina and a compound represented by M13-XM2XM35O12. The volume percent of the compound in the ceramic sintered body is from 3% to 70% inclusive. The ratio of the intensity of XRD from a complex oxide of aluminum and M2 to the intensity of XRD from the compound in the ceramic sintered body is less than 0.05. The average grain diameter of the alumina contained in the ceramic sintered body is from 0.30 (µm) to 3.00 (µm) inclusive. M1 is at least one selected from Sc, Y, and lanthanoid elements, and M2 is at least one selected from lanthanoid elements except any lanthanoid element selected for M1. M3 is at least one of Al and Ga, and X is from 0.003 to 0.500 inclusive.