Nitrogen-Bearing Phosphor Composition for Stable Red-NIR Emission
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Solution Overview
Problem
Conventional phosphors experience significant brightness deterioration when exposed to high-energy excitation sources, necessitating the development of phosphors with improved stability and emission characteristics, particularly in the red and near-infrared ranges.
Innovation Solution
A new phosphor with a Ba26Si51O2N84 crystal structure, activated by elements like Eu, which emits high-intensity red or near-infrared light even when combined with LEDs emitting shorter wavelengths, is synthesized using a method involving firing a mixture of metallic compounds in a nitrogen-containing inert atmosphere at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional phosphors are used with high-energy excitation sources, then the phosphor can emit visible light, but the luminance deteriorates significantly over time
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor by incorporating nitrogen into the crystal structure (forming nitride or oxynitride phosphors with formulas like A26(D,E)51X86 where X includes N and O). This compositional parameter change fundamentally improves resistance to high-energy excitation damage while maintaining emission properties.
Solution Approach 2:
The patent creates composite phosphor materials combining multiple elements (A elements from Mg/Ca/Sr/Ba groups, D=Si, E from B/Al/Ga/In groups, X from O/N/F groups) in a specific crystal structure. This composite approach allows optimization of both emission characteristics and durability against brightness deterioration.
2Illumination intensity
If the phosphor composition is changed to improve emission characteristics, then the emission wavelength and color can be adjusted, but the crystal structure stability may be compromised
Solution Approach 1:
The patent applies local quality by allowing specific element substitutions at particular crystal structure sites. The formula A26(D,E)51X86 shows that D (Si) can be partially replaced by E (B/Al/Ga/In) and X (O/N/F) can be varied, enabling localized compositional adjustments that tune emission while preserving the overall crystal framework stability.
Solution Approach 2:
The patent systematically varies compositional parameters (ratios of A elements, presence of E elements, oxidation states of X) to achieve desired emission wavelengths. These parameter changes are made within constraints that maintain the fundamental A26(D,E)51X86 crystal structure, ensuring stability while enabling color tuning.
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 phosphor exhibits stable emission intensity and durability, suitable for applications in white LEDs, liquid crystal display backlights, projectors, and infrared lighting devices, maintaining brightness without significant degradation under excitation.
Implementation Method 1
the phosphor is excited by an excitation source with high energy such as a vacuum ultraviolet ray, an ultraviolet ray, an electron beam, and blue light so as to emit a visible light ray
Implementation Method 2
firing a raw material mixture, which is a mixture of metallic compounds and can constitute the phosphor by firing, in an inert atmosphere including nitrogen in a temperature range that is 1400° C. or higher and is 2200° C. or lower
Data Source
AI summary
Provided are a new phosphor having emission characteristics different from the conventional nitride or oxynitride phosphor, a manufacturing method, and a light-emitting device. In an embodiment, the phosphor may include inorganic substance having crystal represented by A26(D, E)51X86 including at least A, D, X (A is at least one kind of element selected from Mg, Ca, Sr, and Ba; and D is Si, and X is at least one kind of element selected from O, N, and F); and further includes, if necessary, E (E is at least one kind of element selected from B, Al, Ga, and In) wherein the crystal further includes M (M is at least one kind of element selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, and Yb). Upon irradiation of excitation source, the maximum value of emission peak in a wavelength range from 630 nm to 850 nm may occur.