Blue-Green Phosphor Composition for Thermal Stability
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Solution Overview
Problem
Conventional phosphors experience a significant decrease in quantum efficiency and color shift at elevated temperatures, limiting their performance in lighting applications such as LEDs and fluorescent lamps.
Innovation Solution
Development of phosphor compositions with the formula ((Sr 1-z M z ) 1-(x+w) A w Ce x ) 3 (Al 1-y Si y )O 4+y+3(x-w) F 1-y-3(x-w) , which maintain a high quantum efficiency across a wide range of temperatures, emitting blue-green to green light with a peak wavelength between 485 nm and 540 nm when excited at 405 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional phosphors are used in lighting applications, then they can convert UV radiation to visible light, but their quantum efficiency decreases significantly and color shifts at elevated temperatures
Solution Approach 1:
The patent modifies the chemical composition parameters of the phosphor by incorporating specific ratios of strontium, aluminum, silicon, oxygen, and fluorine in the formula Sr3-x-yAl5-ySiNyO12:F, where x and y are controlled within specific ranges. This compositional parameter optimization enables the phosphor to maintain quantum efficiency above 80% at 150°C while resisting color shifts, directly resolving the temperature-related reliability contradiction
Solution Approach 2:
The invention creates a composite phosphor material that integrates multiple elements (Sr, Al, Si, N, O, F) in a specific crystalline structure. This composite approach combines the advantages of different elements to achieve both high quantum efficiency and thermal stability, allowing the phosphor to withstand elevated temperatures without significant performance degradation or color shift
2Adaptability or versatility
If phosphors are used to convert LED light to different wavelengths, then custom colors and higher luminosity can be produced, but the phosphor composition must be precisely controlled to maintain performance across temperature variations
Solution Approach 1:
The patent establishes specific parameter ranges for the phosphor composition (x between 0.1-2.0, y between 0.1-1.0 in the formula Sr3-x-yAl5-ySiNyO12:F) that enable color customization while maintaining thermal stability. By controlling these compositional parameters within defined boundaries, the invention achieves both versatility in color production and precision in manufacturing consistency across temperature variations
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
These phosphors retain at least 80% of their ambient quantum efficiency at 150°C, minimizing intensity loss and color shifts, thus providing stable and consistent light emission across temperature variations.
Implementation Method 1
A phosphor is a luminescent material that absorbs radiation energy in one portion of the electromagnetic spectrum and emits energy in another portion of the electromagnetic spectrum
Implementation Method 2
Phosphors have been used in mercury vapor discharge lamps to convert the ultraviolet (UV) radiation emitted by the excited mercury to visible light
Data Source
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AI summary
Embodiments of the present techniques provide a related family of phosphors (22) that may be used in lighting systems to generate blue or blue-green light. The phosphors (22) include systems having a general formula of: ((Sr1-zMz)1-(x+w)AwCex)3(Al1-ySiy)O4+y+3(x-w)F1-y-3(x-w) (I), wherein 0<x≤0.10, 0≤y≤0.5, 0≤z≤0.5, 0≤w≤x, A is Li, Na, K, Rb, or Ag or any combinations thereof, and M is Ca, Ba, Mg, Zn, or Sn or any combinations thereof. Advantageously, phosphors (22) made accordingly to these formulations maintain emission intensity across a wide range of temperatures. The phosphors may be used in lighting systems, such as LEDs (10) and fluorescent tubes, among others, to produce blue and blue/green light. Further, the phosphors may be used in blends with other phosphors, or in combined lighting systems, to produce white light suitable for illumination.