Gradient YAG Phosphor for Thermal Quenching in High-Intensity Lighting
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Solution Overview
Problem
Phosphors used in high-intensity lighting applications, such as vehicle lighting and projectors, face a 'thermal quenching' phenomenon where luminous efficiency decreases at high temperatures due to low thermal conductivity, leading to reduced performance and potential thermal damage.
Innovation Solution
A single crystal phosphor with a specific composition and concentration gradient of elements like Y and Ce, featuring a high concentration region for enhanced light emission and a low concentration region for improved thermal conductivity, is designed to mitigate thermal quenching by efficiently dissipating heat and maintaining light emission characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a phosphor is used in high-intensity lighting applications, then light emission is achieved, but thermal quenching occurs and luminous efficiency decreases at high temperatures
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of Ce ions within the YAG phosphor crystal structure. The Ce concentration varies from the surface toward the center, with higher concentration near the surface for enhanced light emission and lower concentration toward the center to reduce thermal quenching. This spatial variation in composition allows different regions to have optimized properties for their specific functional requirements.
Solution Approach 2:
The patent utilizes parameter changes by systematically varying the Ce ion concentration as a gradient from the phosphor surface toward the center. This continuous parameter variation allows optimization of both light emission (requiring higher Ce concentration) and thermal performance (requiring lower Ce concentration in the core), resolving the contradiction between these two opposing requirements.
2Illumination intensity
If a phosphor with high additive concentration is used, then light emission characteristics are enhanced, but thermal conductivity decreases
Solution Approach 1:
The patent implements local quality by establishing a non-uniform distribution of Ce ions within the YAG phosphor. The surface region contains higher Ce concentration to maximize light emission characteristics, while the central region contains lower Ce concentration to maintain high thermal conductivity. This spatial differentiation resolves the contradiction between light emission enhancement and thermal conductivity preservation.
Solution Approach 2:
The patent transitions from a uniform composition approach to a gradient composition approach, adding a spatial dimension to the Ce concentration distribution. By varying concentration along the radial dimension from surface to center, the patent simultaneously optimizes both optical performance (at the surface) and thermal performance (at the center) within a single phosphor structure.
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 phosphor effectively suppresses thermal quenching, enhances thermal conductivity, and prevents thermal damage to the light source device, while maintaining high light emission characteristics even at elevated temperatures.
Implementation Method 1
a first concentration in a radial direction from a surface toward a center of the phosphor and a second concentration lower than the first concentration in the radial direction from the surface toward the center of the phosphor
Implementation Method 2
a high concentration region having a high additive concentration and at least one low concentration region lower in additive concentration than the high concentration region, wherein the at least one low concentration region surrounds the high concentration region in a cross section of the phosphor parallel to a longitudinal direction of the phosphor
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A phosphor includes a high concentration region and at least one of low concentration regions lower in concentration of an additive than the high concentration region. The high concentration region surrounds at least one of low concentration regions.