Europium Strontium Nitride Phosphor Brightness Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing phosphors, such as silicon nitride-based phosphors, face challenges including the degradation of phosphor brightness over time due to exposure to excitation sources, high production costs, and difficulties in achieving uniform composition and impurity-free alloys, which affect luminescent properties.
Innovation Solution
A method involving the use of an alloy powder with a specific particle size distribution and composition, including a weight-average median diameter of 5 μm to 40 μm, and the presence of activating elements like Eu and alkaline-earth metals, which is milled in a nitrogen-containing atmosphere to produce high-performance phosphors with improved brightness and luminescent efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional phosphors are used with high-energy excitation sources, then the phosphors can emit ultraviolet, visible, or infrared light, but the brightness of the phosphors decreases over time due to degradation
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor material by incorporating specific ratios of Si, Al, and rare-earth elements (Eu, Ce, Pr, Nd) to create a more stable crystal structure that resists degradation under excitation while maintaining high brightness
Solution Approach 2:
The patent creates a composite phosphor material combining silicon nitride, aluminum nitride, and rare-earth element compounds to achieve both high brightness and improved stability under excitation sources
2Manufacturing precision
If high-temperature, high-pressure furnaces are used for synthesis, then phosphors can be produced, but production costs increase significantly
Solution Approach 1:
The patent performs preliminary mixing and uniform distribution of raw materials (SiO2, Al2O3, rare-earth oxides/nitrides) before heating, which ensures composition uniformity is achieved at lower temperatures and reduces the need for expensive high-pressure equipment
Solution Approach 2:
The patent uses readily available, low-cost raw materials such as silicon oxide, aluminum oxide, and common rare-earth compounds instead of requiring expensive specialized materials or equipment
3Manufacturing precision
If alkaline-earth metal nitrides are used as raw materials, then phosphors can be synthesized, but the methods become problematic for industrial large-scale synthesis due to sensitivity to air and moisture
Solution Approach 1:
The patent uses silicon nitride and aluminum nitride as intermediary compounds that are stable in air and moisture, which then react during heating to form the desired phosphor structure, avoiding the need to handle sensitive alkaline-earth metal nitrides directly
Solution Approach 2:
The patent replaces sensitive, expensive alkaline-earth metal nitrides with stable, inexpensive alternatives like silicon nitride and aluminum nitride that can be handled easily in industrial settings
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 method enables the production of phosphors with enhanced brightness and luminescent efficiency, maintaining performance over time and reducing production costs by avoiding the need for high-temperature, high-pressure furnaces and ensuring uniform composition.
Implementation Method 1
which is nitridated or oxidized to produce phosphors with improved brightness and luminescent efficiency
Implementation Method 2
which is nitridated or oxidized to produce phosphors with improved brightness and luminescent efficiency
Implementation Method 3
produces phosphors with high brightness and luminescent efficiency, emitting yellow to orange or red light
Data Source
AI summary
A nitride phosphor contains europium as an activating element and strontium, or strontium and calcium, as divalent metal elements. The phosphor further includes aluminum and silicon. Of the europium in the phosphor, at least 85% is in the form of Eu2+. The phosphor has a peak emission wavelength of from 590 nm to 650 nm. A phosphorescent body that includes the phosphor can be suitable for converting a wavelength of at least a portion of light emitted from an excitation light source in a light-emitting device.