Nitride Red Phosphors Halogen Gettering Oxygen
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Solution Overview
Problem
Existing red phosphors in RGB lighting systems suffer from low luminous flux, brightness, and high cost due to impurity oxygen, leading to inadequate color rendering and high color temperature in backlighting and warm white-light applications.
Innovation Solution
Development of nitride-based red phosphors using (Ca, Sr, Ba)AlSiN3 compounds activated with divalent europium, incorporating halogens like F and Cl to reduce oxygen impurities and enhance photoluminescent properties, resulting in higher color rendering indexes and lower correlated color temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional red phosphors are used in RGB lighting systems, then the system can provide red light emission, but the luminous flux and brightness are insufficient due to impurity oxygen
Solution Approach 1:
The patent changes the chemical composition parameters by incorporating halogens (F, Cl) into the nitride-based phosphor structure and adjusting the ratios of Ca, Sr, Ba, and Al to optimize luminous flux while maintaining color rendering quality. This resolves the contradiction by modifying material parameters to achieve both high brightness and reliable color performance
Solution Approach 2:
The patent creates composite nitride-based phosphor materials combining multiple elements (Ca, Sr, Ba, Al, N, and halogens) to achieve superior luminous flux and color rendering properties that cannot be obtained with conventional single-component phosphors, thereby resolving the contradiction between brightness and color rendering quality
2Illumination intensity
If conventional red phosphors are used, then the system can operate, but the color rendering index is inadequate and correlated color temperature is too high
Solution Approach 1:
The patent modifies the chemical composition parameters by incorporating halogens and adjusting the Ca-Sr-Ba-Al ratios to achieve lower correlated color temperature and improved color rendering index while maintaining high brightness, thereby resolving the contradiction between brightness and color rendering performance
3Productivity
If nitride-based red phosphors with halogens are used, then luminous flux and brightness are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent incorporates halogens into the phosphor structure during the initial synthesis process rather than as a separate post-processing step, which improves luminous flux while avoiding additional manufacturing complexity. The halogen incorporation is achieved through controlled reaction conditions during phosphor fabrication
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 nitride-based red phosphors provide improved luminous flux, brightness, and color rendering, achieving deeper red emission with reduced oxygen content and halogen-induced gettering effects, suitable for RGB lighting systems and warm white-light applications.
Implementation Method 1
incorporating halogens like F and Cl to reduce oxygen impurities and enhance photoluminescent properties
Implementation Method 2
nitride-based red phosphors based on (Ca, Sr, Ba)AlSiN3 type compounds activated with divalent europium
Data Source
AI summary
Embodiments of the present invention are directed to nitride-based, red-emitting phosphors in red, green, and blue (RGB) lighting systems, which in turn may be used in backlighting displays and warm white-light applications. In particular embodiments, the red-emitting phosphor is based on CaAlSiN3 type compounds activated with divalent europium. In one embodiment, the nitride-based, red emitting compound contains a solid solution of calcium and strontium compounds (Ca,Sr)AlSiN3:Eu2+, wherein the impurity oxygen content is less than about 2 percent by weight. In another embodiment, the (Ca,Sr)AlSiN3:Eu2+ compounds further contains a halogen in an amount ranging from about zero to about 2 atomic percent, where the halogen may be fluorine (F), chlorine (Cl), or any combination thereof. In one embodiment at least half of the halogen is distributed on 2-fold coordinated nitrogen (N2) sites relative to 3-fold coordinated nitrogen (N3) sites.