Amber Luminescent Ceramic Phase Control for Higher Quantum Yield
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Solution Overview
Problem
Amber-emitting luminescent ceramics containing (Ba,Sr,Ca) 2-x Si 5-y Al y O y :Eu x suffer from reduced quantum yield and chemical instability due to the presence of the non-luminescent (Ba,Sr) 3 Si 3 O 3 N 4 :Eu phase, which absorbs blue light and hydrolyzes in moist air, leading to light scattering and adhesive issues.
Innovation Solution
A post-sintering thermal treatment under high nitrogen pressure at elevated temperatures reduces the amount of the 3334 phase, increases the BOSE phase, and adjusts the oxygen content, enhancing the conversion efficiency and chemical stability of the ceramic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ambient pressure firing is used to form luminescent ceramic, then the manufacturing process is simple, but the ceramic contains non-luminescent 3334 phase that reduces quantum yield and causes chemical instability
Solution Approach 1:
The patent applies preliminary action by conducting a post-sintering thermal treatment after the initial ambient pressure firing. This additional thermal treatment step transforms the non-luminescent 3334 phase into the luminescent 258 phase, thereby improving quantum yield and chemical stability while maintaining the simplicity of the initial firing process.
2Ease of manufacture
If the 3334 phase is present in the ceramic, then the manufacturing process is straightforward, but the ceramic absorbs blue light and hydrolyzes in moist air causing light scattering and adhesive issues
Solution Approach 1:
The patent converts the harmful 3334 phase into a beneficial luminescent phase through post-sintering thermal treatment. The non-luminescent 3334 phase that causes light absorption and hydrolysis is transformed into the luminescent 258 phase, thereby converting a harmful factor into a beneficial one that enhances quantum yield and chemical stability.
3Reliability
If post-sintering thermal treatment under high nitrogen pressure is applied, then quantum yield and chemical stability are improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies parameter changes by modifying the thermal treatment parameters after sintering. Specifically, a post-sintering thermal treatment is applied under high nitrogen pressure at elevated temperatures, which transforms the non-luminescent 3334 phase into the luminescent 258 phase, thereby improving quantum yield and chemical stability.
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 treatment increases the quantum yield and chemical stability of the amber-emitting luminescent ceramics, improving their luminescence conversion efficiency and reducing light scattering, while maintaining the desired amber emission.
Implementation Method 1
A post-sintering thermal treatment under high nitrogen pressure at temperatures of at least 1300°C reduces the amount of the (Ba,Sr) 3 Si 3 O 3 N 4 :Eu phase, increases the amount of (Ba 1-x Sr x ) 2-z Si 5-y O 4y N 8-4y :Eu z phase
Implementation Method 2
The precursor powders are formed into ceramic green bodies, sintering the ceramic green bodies into densely sintered composite ceramics
Implementation Method 3
Amber-emitting luminescent ceramic (Ba,Sr,Ca) 2-x Si 5-y Al y O y N 8-y :Eu x may be formed by ambient pressure firing
Data Source
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AI summary
Embodiments of the invention include a luminescent ceramic including (Ba1-xSrx)2-zSi5-yO4yN8-4y:Euz 258 phase wavelength converting material (0.5 ≤ x ≤ 0.9; 0 ≤ y ≤ 1;0.001 ≤ z ≤ 0.02) and M3Si3O3N4 3334 phase material (M = Ba, Sr, Eu). The M3Si3O3N4 3334 phase material comprises no more than 5 weight % of the material.