Beta-SiAlON Phosphor Manufacturing for LED Wavelength Control
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Solution Overview
Problem
The luminescent efficiency of Eu-doped β-SiAlON deteriorates when attempting to reduce the wavelength and bandwidth of its fluorescent spectrum, and there is poor reproducibility of luminescent properties in its manufacturing process.
Innovation Solution
A method of manufacturing β-SiAlON with controlled physical properties, including specific ranges for Al, O, Si, N, and Eu content, baked in a nitrogen atmosphere at high temperatures, followed by optional annealing and acid treatment to achieve high fluorescent efficiency and reduced wavelength and bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the wavelength and bandwidth of the fluorescent spectrum of β-SiAlON are reduced, then the color purity and precision are improved, but the luminescent efficiency deteriorates
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Al content (0.3-1.2 mass%), O content (0.15-1 mass%), O/Al molar ratio (0.9-1.3), and baking temperature (1850°C-2050°C) to achieve the desired balance between wavelength reduction and luminescent efficiency maintenance. This systematic parameter optimization resolves the contradiction by finding the optimal operating point where both color purity and efficiency are satisfied.
2Illumination intensity
If the luminescent efficiency is improved by doping Eu, then the brightness is enhanced, but the reproducibility of luminescent properties deteriorates
Solution Approach 1:
The patent resolves the reproducibility issue by establishing precise parameter ranges including Eu content (0.3-0.7 mass%), Al content (0.3-1.2 mass%), and O/Al molar ratio (0.9-1.3), combined with controlled baking temperatures (1850°C-2050°C). These defined parameters ensure consistent luminescent properties across multiple manufacturing batches while maintaining high efficiency.
Solution Approach 2:
The patent employs feedback control through measuring the luminescent properties and adjusting the composition parameters accordingly. By monitoring the luminescent efficiency and reproducibility, the manufacturing process can be optimized to maintain Eu doping within the optimal range of 0.3-0.7 mass%, ensuring both high brightness and consistent performance.
3Measurement precision
If the O content is reduced to narrow the bandwidth, then the color precision is improved, but the luminescent efficiency deteriorates
Solution Approach 1:
The patent resolves this contradiction by controlling the O content within a specific range (0.15-1 mass%) and maintaining the O/Al molar ratio between 0.9-1.3. This balanced approach allows bandwidth reduction for color precision while preventing excessive O depletion that would harm luminescent efficiency. The interrelated control of O content and O/Al ratio ensures optimal performance.
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 method achieves high fluorescent efficiency and reproducibility of β-SiAlON with reduced wavelength and bandwidth, suitable for use in white light emitting diodes and ultraviolet light emitting diodes, maintaining performance across various conditions.
Implementation Method 1
the powdered material is baked in the baking step at temperatures from 1850°C to 2050°C in a nitrogen atmosphere
Implementation Method 2
β-SiAlON produced in a first heat treatment step is subjected to acid treatment in the second heat treatment step to improve its crystallinity
Implementation Method 3
β-SiAlON available for luminescent devices such as white light emitting diodes using blue light emitting diode chips or ultraviolet light emitting diode chips
Implementation Method 4
the wavelength and bandwidth of the fluorescent spectrum of the β-SiAlON
Data Source
AI summary
A method of manufacturing β-SiAlON represented by a general formula Si6-zAlzOzN8-z: Eu, including a baking step for baking a powdered material that contains Al content from 0.3 to 1.2 mass%, O content from 0.15 to 1 mass%, O/Al molar ratio from 0.9 to 1.3, Si content from 58 to 60 mass%, N content from 37 to 40 mass%, N/Si molar ratio from 1.25 to 1.45, and Eu content from 0.3 to 0.7 mass%. The baking step is a step of baking the powdered material in a nitrogen atmosphere at temperatures from 1850°C to 2050°C, and the manufactured β-SiAlON satisfies 0.280 ≤ x ≤ 0.340 and 0.630 ≤ y ≤ 0.675 on the CIExy chromaticity coordinate.