Beta-type Sialon Phosphor Brightness via High-Temp Eu Dissolution
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Solution Overview
Problem
Conventional β type Sialon fluorescent substances synthesized at low temperatures have insufficient doping atom dissolution in the crystal structure, leading to reduced brightness, and the composition range for achieving sufficient brightness is uncertain, making it difficult to obtain a reproducible fluorescent substance with enhanced luminescence properties for white LEDs.
Innovation Solution
A β type Sialon fluorescent substance with a specific composition (Si6-zAlzOzN8-z) containing Eu in a solid solution, where z is between 0.24 and 0.42, and Eu content is 0.05-0.25% by atom, is synthesized at high temperatures (1820-2200°C) to ensure sufficient dissolution and luminescence, resulting in a powder with optimal particle size and luminescence properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If β type Sialon is synthesized at low temperature (1500°C), then the synthesis process is easier and energy consumption is lower, but doping atoms are not sufficiently dissolved in solid solution into the crystal structure, resulting in insufficient brightness
Solution Approach 1:
The patent changes the synthesis temperature parameter from conventional low temperature (1500°C) to high temperature (1820-2200°C) to achieve sufficient dissolution of doping atoms into the crystal structure, thereby obtaining fluorescent substance with enhanced brightness while maintaining ease of manufacture through a systematic approach to high-temperature synthesis
2Illumination intensity
If synthesis temperature is increased to 1820-2200°C to achieve sufficient doping atom dissolution, then brightness is enhanced, but the composition range for realizing enough brightness is uncertain and reproducibility is poor
Solution Approach 1:
The patent establishes specific parameter ranges: z in Si6-zAlzOzN8-z is 0.24-0.42 and Eu content is 0.05-0.25% by atom. By defining these precise ranges, the patent achieves both enhanced brightness and reproducible manufacturing, resolving the uncertainty in composition range
Solution Approach 2:
The patent employs dynamic adjustment of synthesis conditions within the established ranges, allowing flexible control of doping atom dissolution while maintaining reproducibility. The high temperature synthesis process dynamically adapts to achieve optimal brightness within the specified composition ranges
3Illumination intensity
If Eu content is increased to enhance luminescence brightness, then emission intensity improves, but the luminescence becomes very sensitive to composition changes and reproducibility deteriorates
Solution Approach 1:
The patent optimizes Eu content to a specific range (0.05-0.25% by atom) rather than using high concentrations. This optimized range achieves sufficient emission intensity while minimizing sensitivity to composition changes, thereby maintaining high reliability and reproducibility in the fluorescent substance
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 resulting β type Sialon fluorescent substance exhibits a broad excitation range from ultraviolet to visible light, emitting green light with a peak wavelength between 500-550 nm, enhancing the brightness and stability of white LEDs when used with blue or ultraviolet light sources.
Implementation Method 1
An LED has its phosphor excited by a source of excitation high in energy such as ultraviolet or blue light to emit a visible light radiation
Implementation Method 2
a β type Sialon synthesized at a temperature as high as 1820 to 2200 °C so that Eu ions are sufficiently dissolved in solid solution into the crystal structure
Data Source
Figure 1
AI summary
A β type Sialon fluorescent substance is disclosed that is capable of achieving enhanced brightness of a white light emitting diode using blue to ultraviolet light as a light source. In the fluorescent substance which contains not less than 90 % by mass of a β type Sialon composition represented by general formula: Si6-zAlzOzN8-z as a host material wherein z is not less than 0.24 and not more than 0.42, Eu is present dissolved in solid solution as a luminescent center at a content of 0.05 to 0.2 % by atom. The β type Sialon fluorescent substance is preferably in the form of a powder having an average particle size of not less than 1 µm and not more than 20 µm. A white LED of good luminescent characteristics can be obtained by using a blue or ultraviolet light emitting diode as a excitation light source in combination with a fluorescent substance that emits yellow or red light.