Red Phosphor Segmented Roasting for LED Luminous Efficiency
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Solution Overview
Problem
Current red phosphors for white-light LEDs suffer from low luminous efficiency, poor chemical stability, and high manufacturing costs due to high-temperature and high-pressure synthesis methods, leading to inadequate color rendering and luminous attenuation performance.
Innovation Solution
A new red phosphor with the chemical formula Ca1-y-m-e-rYyMmXxPpZn:EuRr is synthesized using a segmented roasting and normal-pressure high-temperature solid-state method, incorporating alkali metals and specific elements like Y, Dy, and P to enhance luminous intensity and stability, and a low-cost, pollution-free manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high-temperature and high-pressure one-step synthesis method is used to manufacture red phosphor, then the phosphor can be produced, but the manufacturing cost increases and the process becomes complex
Solution Approach 1:
The synthesis process is divided into two distinct stages: first, preparing a precursor mixture containing calcium nitride, silicon nitride, aluminum nitride, and europium oxide at lower temperatures (900-1100°C); second, performing a high-temperature treatment (1300-1500°C) to complete the phosphor formation. This segmentation allows the complex high-pressure synthesis to be replaced with simpler, sequential low-pressure processes using standard equipment.
2Ease of manufacture
If high-temperature and high-pressure one-step synthesis method is used to manufacture red phosphor, then the phosphor can be produced, but the manufacturing cost increases
Solution Approach 1:
The precursor preparation step performs preliminary chemical reactions at lower temperatures to form intermediate compounds and distribute europium activators uniformly before the final high-temperature treatment. This preliminary action reduces the overall energy requirement and allows the use of less expensive equipment compared to direct one-step high-temperature synthesis.
3Illumination intensity
If conventional red phosphor is used in white-light LED, then the LED can be manufactured, but the luminous efficiency is low and color rendering is poor
Solution Approach 1:
The phosphor's compositional parameters are optimized by controlling the ratios of calcium, silicon, aluminum, and europium, as well as adjusting the sintering temperature and duration. These parameter changes produce a phosphor with enhanced red emission intensity and improved color rendering properties, directly addressing the limitations of conventional red phosphors in LED applications.
4Reliability
If conventional red phosphor is used in white-light LED, then the LED can be manufactured, but the chemical stability is poor and luminous attenuation occurs
Solution Approach 1:
The phosphor employs a composite structure combining calcium silicate nitride base material with aluminum substitution and europium activation. This composite composition enhances chemical stability by forming a more robust crystal lattice that resists degradation, thereby reducing luminous attenuation over time and improving the long-term reliability of LED devices.
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 new phosphor exhibits improved luminous efficiency, anti-luminous attenuation performance, and chemical stability, meeting the requirements of white-light LEDs with reduced equipment demands and energy consumption.
Implementation Method 1
a red phosphor that can be effectively excited by ultraviolet, violet light or blue light and applied to the white-light LED
Implementation Method 2
performing segmented roasting to these mixed raw materials in the tubular furnace with the protective atmosphere adopting the normal-pressure high-temperature solid-state method
Data Source
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AI summary
The present invention discloses a white-light LED red phosphor and method of manufacturing the same. The chemical formula of the phosphor is Ca1-y-m-e-rYyMmXx-pPpZzNn: Eue, Rr, wherein 0.001≤y≤0.2,0.001≤m≤0.2,0.5≤x,z≤1.5, 0.001≤p≤0.1,2≤n≤4,0.01≤e≤0.2,0.001≤r≤0.1, M is selected from at least one of Sr, Ba, Sc, Li, Na and K; X is selected from at least one of B, Al and Ga, wherein Al is must; Z is selected from Si, V, and Nb, wherein Si is must; R is selected from at least one of Dy, Er, Tm, and Lu, wherein Dy is must. The manufacturing method comprises: Weighing the raw materials according to the chemical formula components in the structural formula (1) and stoichiometric ratio; sealing tightly after mixing them in a protective atmosphere, and then performing segmented roasting in the protective atmosphere adopting the normal-pressure high-temperature solid-state method, finally obtaining the white-light LED red phosphor after post-processing. The phosphor according to the present invention has features such as good chemical stability, high luminous efficiency, and good anti- luminous attenuation performance, etc. Further, this manufacturing method is easy to operate, pollution-free, and low cost.