Nitride Phosphor Composition for LED Brightness Stability
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Solution Overview
Problem
Conventional phosphors used in lighting and display devices suffer from reduced brightness and stability when exposed to high-energy excitation sources, necessitating the development of phosphors with improved emission characteristics and thermal stability.
Innovation Solution
An inorganic phosphor with a specific compositional formula, M d A e D f E g X h, where M, A, D, E, and X are selected elements, is synthesized using a firing process in a nitrogen-containing inert atmosphere, resulting in a phosphor with high emission intensity and stability, suitable for white light-emitting diodes and image display devices.
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 decreases over time due to brightness deterioration
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor by incorporating nitrogen into the crystal structure (forming oxynitride or nitride phosphors) and optimizing the ratio of metal elements. This compositional parameter change fundamentally improves the phosphor's resistance to brightness deterioration under high-energy excitation while maintaining high emission intensity.
Solution Approach 2:
The patent creates a composite phosphor material by combining multiple metal elements (M element from transition metals, A element from alkaline earth metals, D element from group 14 elements, E element from boron family or rare earth elements) with nitrogen in a specific compositional formula. This composite structure leverages the synergistic effects of different elements to achieve both high brightness and excellent stability.
2Illumination intensity
If the phosphor composition is modified to improve emission characteristics, then the emission color and intensity can be optimized, but the manufacturing process becomes more complex
Solution Approach 1:
The patent establishes specific parameter ranges for each element in the compositional formula (M d A e D f E g N h) to achieve desired emission characteristics. By defining these compositional parameters, the patent enables systematic optimization of emission color and intensity while maintaining manufacturability through controlled synthesis conditions.
Solution Approach 2:
The patent employs a nitrogen-containing inert atmosphere during the firing process to prevent oxidation and control the formation of oxynitride or nitride phases. This controlled atmosphere simplifies the manufacturing process by providing a stable environment that ensures reproducible results without requiring overly complex processing equipment.
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 high emission efficiency and durability, maintaining brightness even under high-energy excitation, and is suitable for various lighting and display applications, including white LEDs and image display devices, with enhanced chemical and thermal stability.
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
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 3
firing a raw material mixture of metal compounds, which can constitute the phosphor according to the compositional formula (1), by heating the mixture in a temperature range of 1,200 °C or higher to 2,200 °C or lower in an inert atmosphere including nitrogen
Data Source
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AI summary
Provided is a chemically and thermally stable phosphor having different emission characteristics than the conventional phosphor and exhibiting high emission intensity if combined with an LED of 470 nm or less. The phosphor of the present invention is represented by a composition formula: MdAeDfEgXh (d+e+f+g+h = 1; M is one or more kinds of elements selected from Mn, Ce, Pr, Nd, Sm, Eu, Tb, Dy, and Yb; A is one or more kinds of elements selected from Mg, Ca, Sr, and Ba; D is one or more kinds of elements selected from Si, Ge, Sn, Ti, Zr, and Hf; E is one or more kinds of elements selected from B, Al, Ga, In, Sc, Y, and La; and X is one or more kinds of elements selected from O, N, and F) and parameters d, e, f, g, and h satisfy the predetermined condition.