Red Long-Afterglow Phosphor Composition for Stable White Powder
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Solution Overview
Problem
Existing red luminescent phosphors suffer from chemical instability, require special gas for synthesis, emit non-white colors, have short afterglow duration, and afterglow wavelength deviates from red.
Innovation Solution
A red-luminescent phosphor with the formula MgxZnyGe2O3: aMn2+, bEu3+, cR3+ is synthesized, where Mn2+ acts as an activator, Eu3+ as a first sensitizer, and R3+ as a second sensitizer, allowing for chemical stability and white powder color without special gas synthesis, with afterglow duration ranging from minutes to hours and initial intensity up to 10 times higher than (Mg0.5Zn0.5)GeO3: Mn2+, Eu3+ phosphors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If sulfide phosphors such as ZnS: Cu2+, Mn2+ are used to achieve red luminescence, then orange-red emission is obtained, but chemical instability and poor heat stability occur
Solution Approach 1:
The patent changes the chemical composition parameters by replacing sulfide-based phosphors with silicate-based phosphors (MSi2O2N2: Yb, R), fundamentally altering the chemical stability characteristics while maintaining red luminescence emission
Solution Approach 2:
The patent employs composite material design by combining multiple elements (M, Si, O, N, Yb, and other rare earth elements R) to create a new phosphor system that integrates both chemical stability and red luminescence properties that individual components cannot achieve alone
2Shape
If oxysulfide based phosphors such as Y2O2S: Eu3+, Mg2+, Ti4+ are used to achieve white powder color, then white powder is obtained, but special gas (sulfur and reducing gas) is required for synthesis
Solution Approach 1:
The patent extracts and eliminates the sulfur component from the phosphor system, transitioning from oxysulfide (Y2O2S) to silicate (MSi2O2N2) based materials, thereby removing the requirement for sulfur gas and reducing gas during synthesis while maintaining white powder color
Solution Approach 2:
The patent changes the chemical composition parameters by replacing sulfur-containing compounds with sulfur-free silicate compounds, fundamentally altering the synthesis conditions to eliminate special gas requirements while preserving the desired white powder color
3Illumination intensity
If (Mg,Zn)GeO3 series red phosphors are used to achieve red luminescence, then red emission is obtained, but afterglow duration is short compared to green phosphors
Solution Approach 1:
The patent employs composite material design by combining Mg and Zn in specific ratios within the silicate structure (MgxZn1-xSi2O2N2), creating a composite phosphor system that achieves both red luminescence and extended afterglow duration through synergistic effects of the multiple elements
Solution Approach 2:
The patent optimizes compositional parameters (x values for Mg and Zn ratios, rare earth element concentrations) to tune the afterglow characteristics, achieving prolonged emission duration by adjusting the chemical composition while maintaining red emission
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 achieves chemically stable, white emission with extended afterglow duration and intensity, excitable by visible light, overcoming the limitations of existing red phosphors.
Implementation Method 1
Mn2+ serves as activator
Implementation Method 2
red-luminescent phosphor with long afterglow
Implementation Method 3
Eu3+ serves as first sensitizer
Implementation Method 4
R3+ serves as second sensitizer
Implementation Method 5
Persistent luminescence is an optical phenomenon in which a material emits energy in the visible spectrum for an appreciable time after the excitation source is removed
Data Source
AI summary
A red-luminescent long-afterglow phosphor, represented by MgxZnyGezO3: aMn2+, bEu3+, cR3+. The phosphor is a kind of oxide compound based white powder. The phosphor powder synthesis process is environmentally friendly, no sintering-assisted gas required and no harmful gas generated during or after sintering. The phosphor powder can be excited by UV and is chemically stable.