YAG Single Crystal Phosphor for High Efficiency White Light
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Solution Overview
Problem
Existing light-emitting devices using YAG-based phosphors primarily produce white light with limited color rendering properties and high manufacturing costs due to the need for expensive rare earth elements like Lu, and they struggle to achieve unconventional fluorescence colors.
Innovation Solution
A YAG-based single crystal phosphor with a composition of (Y1-a-b Lu a Ce b )3+c Al 5-c O12, where 0≤a≤0.9994, 0.0002≤b≤0.0067, and -0.016≤c≤0.315, is developed using the Czochralski process, allowing for the production of fluorescence in unconventional colors by optimizing Ce concentration and crystal structure, reducing the need for Lu and enhancing internal quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If YAG-based phosphor with high Lu concentration is used to achieve high internal quantum efficiency, then the light emission efficiency is improved, but the manufacturing cost increases due to expensive rare earth elements
Solution Approach 1:
The patent changes the compositional parameters of the YAG-based phosphor by optimizing the ratios of Y, Lu, and Ce elements. Specifically, it uses a composition formula of (Y1-a-bLuaCeb)3Al5-cO12 where the parameters are controlled within specific ranges: 0≤a≤0.9994, 0.0002≤b≤0.0067, and -0.016≤c≤0.315. This parameter optimization achieves high internal quantum efficiency while reducing dependence on expensive Lu elements.
Solution Approach 2:
The patent creates a composite phosphor material combining multiple elements (Y, Lu, Ce, Al, O) in specific proportions. The composite structure allows the material to benefit from the high quantum efficiency of Lu-containing phases while the overall composition is optimized to reduce the total amount of expensive rare earth elements needed, thus lowering manufacturing costs.
2Ease of manufacture
If conventional YAG-based phosphor composition is used to produce white light, then the manufacturing process is simple, but the color rendering properties are limited and color temperature cannot be adjusted flexibly
Solution Approach 1:
The patent employs parameter changes to achieve flexible color rendering by controlling the compositional variables a, b, and c within specific ranges. By adjusting these parameters, the emission characteristics including color temperature and color rendering properties can be tuned while maintaining a relatively simple manufacturing process using the Czochralski method for single crystal growth.
Solution Approach 2:
The patent applies local quality by creating regions with different Ce concentrations within the crystal structure. The compositional formula allows for spatial variation in element distribution, where Ce acts as an activator with concentration b controlled within 0.0002≤b≤0.0067. This local optimization of activator distribution enables flexible color rendering while keeping the overall manufacturing process simple.
3Illumination intensity
If high Ce concentration is used in YAG-based phosphor to enhance fluorescence emission, then the brightness is improved, but the manufacturing cost increases and internal quantum efficiency optimization becomes difficult
Solution Approach 1:
The patent optimizes the Ce concentration parameter b within a specific range (0.0002≤b≤0.0067) to achieve the best balance between fluorescence brightness and internal quantum efficiency. This parameter optimization ensures that sufficient Ce is present to provide bright fluorescence emission while avoiding excessive Ce concentration that would increase costs and complicate efficiency optimization. The synergistic effect of multiple parameters (a, b, c) is optimized together to achieve high brightness with controlled manufacturing complexity.
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 single crystal phosphor achieves high internal quantum efficiency and flexible color rendering properties, enabling the creation of white light with improved color temperature and reduced manufacturing costs by using lower Ce concentrations, and can produce white light with high color rendering indices when combined with blue and reddish phosphors.
Implementation Method 1
a yellowish phosphor to absorb the light emitted by the light-emitting element and produce a yellowish fluorescence
Implementation Method 2
the preparation of oxide mixture sinter which is melted throughout and homogenized
Implementation Method 3
a light-emitting device having a YAG-based single crystal phosphor
Data Source
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Figure 3A~3B
Figure 4
AI summary
Provided are: a YAG-based single crystal phosphor which produces fluorescence of a non-conventional color; and a phosphor-containing member and a light emitting device, each of which is provided with this single crystal phosphor. Provided as one embodiment of the present invention is a single crystal phosphor which has a composition represented by composition formula (Y1-a-bLuaCeb)3+cAl5-cO12 (wherein 0 ≤ a ≤ 0.9994, 0.0002 ≤ b ≤ 0.0067 and -0.016 ≤ c ≤ 0.315), and which has an emission spectrum having CIE chromaticity coordinates x and y satisfying the relation -0.4377x + 0.7384 ≤ y ≤ -0.4585x + 0.7504 when the peak wavelength of the excitation light is 450 nm at the temperature of 25°C.