Rare Earth Aluminum Garnet Phosphor Wavelength Control
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Solution Overview
Problem
The high cost and rarity of elements like Ga, Lu, and Sc used in conventional YAG-type phosphors make it difficult to produce light-emitting devices with efficient green or blue-green light emission, and there is a challenge in achieving highly efficient phosphors with emission peaks below 530 nm without using expensive materials.
Innovation Solution
A rare earth aluminum garnet type phosphor is developed, where the combination of rare earth elements and aluminum is partially replaced with alkaline earth metals like zirconium (Zr) or hafnium (Hf), allowing for control of emission wavelength without using rare and expensive elements, and the phosphor is used in light-emitting devices to convert primary light into long wavelength light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional YAG-type phosphors use rare elements like Ga, Lu, and Sc to achieve efficient green or blue-green light emission, then the emission efficiency and color quality are improved, but the production cost increases significantly
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor by replacing rare elements (Ga, Lu, Sc) with abundant elements (Mg, Al, Si, Ca, Sr, Ba). Specifically, it uses compounds with formulas like (Ca,Sr,Ba)3(Al,Mg)(Si,N)6O12:Eu2+ and (Ca,Sr,Ba)2Si5N8:Eu2+, where the cation ratios and element substitutions are adjusted to optimize emission properties while using inexpensive materials.
Solution Approach 2:
The patent replaces expensive rare elements with cheap, abundant elements. It uses common materials like MgO, Al2O3, SiO2, CaCO3, SrCO3, BaCO3, and Eu2O3 as raw materials, which are significantly less expensive than Ga, Lu, and Sc compounds, thereby reducing production costs while maintaining phosphor functionality.
2Measurement precision
If conventional phosphors use rare elements to achieve emission peaks below 530 nm, then the wavelength control is improved, but the material availability and cost-effectiveness deteriorate
Solution Approach 1:
The patent achieves precise wavelength control by adjusting the compositional parameters of abundant elements. By varying the ratios of Ca/Sr/Ba, Al/Mg/Si, and O/N in the phosphor formula (Ca,Sr,Ba)3(Al,Mg)(Si,N)6O12:Eu2+, it tunes the emission peak across the blue-green region (480-530 nm) using only common materials, eliminating the need for rare elements like Lu and Sc.
3Reliability
If rare elements are used in phosphor composition, then the emission performance is improved, but the rarity and expense of materials increase
Solution Approach 1:
The patent substitutes expensive rare elements with inexpensive common materials. It uses abundant resources like MgO, Al2O3, SiO2, CaCO3, SrCO3, BaCO3, and Eu2O3 to create phosphors with formulas such as (Ca,Sr,Ba)3(Al,Mg)(Si,N)6O12:Eu2+ and (Ca,Sr,Ba)2Si5N8:Eu2+, achieving reliable emission performance without relying on costly rare elements.
Solution Approach 2:
The patent creates composite phosphor materials combining multiple abundant elements in specific ratios. The composite structure (Ca,Sr,Ba)3(Al,Mg)(Si,N)6O12:Eu2+ integrates the advantages of different elements: Ca/Sr/Ba for host lattice stability, Al/Mg for structural framework, Si for network formation, and Eu2+ for luminescence, achieving high performance through synergistic combination rather than relying on single rare elements.
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
This approach enables the production of light-emitting devices that emit green or blue-green light efficiently at reduced production costs, with improved color rendering and hue, using more abundant materials, and achieves emission peaks in the desired wavelength range.
Implementation Method 1
a phosphor and a light source for generating primary light with which the phosphor is irradiated. The rare earth aluminum garnet type phosphor of the present invention is used as the phosphor, and the primary light is wavelength converted into long wavelength light
Data Source
AI summary
The present invention provides a new phosphor with a controllable emission wavelength without using a number of rare and expensive raw materials in forming the composition. The phosphor includes a compound including a fluorescent ion and having a garnet structure including a rare earth element, aluminum, and oxygen. The compound has such a composition that a combination of the rare earth element and the aluminum of the compound is partially replaced with a combination of alkaline earth metal and zirconium (Zr) or alkaline earth metal and hafnium (Hf).