Core-shell Silicate Luminescent Material for Electron Beam Stability
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Solution Overview
Problem
Conventional sulfide-based phosphor powders are unstable under long-term electron beam bombardment, leading to decomposition and reduced luminous efficiency in field emission devices.
Innovation Solution
A core-shell structured silicate luminescent material with the molecular formula MLn1-xSiO4:xRE@SiO2 is developed, where M is selected from Li, Na, and K, Ln is Y, Sc, Lu, or La, and RE is Tb, Gd, Sm, Eu, Dy, Ce, or Tm, with a method involving sol-gel processing to create a stable matrix that resists decomposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional sulfide-based phosphor powder is used, then the material can be manufactured with simple processes, but the matrix becomes unstable under long-term electron beam bombardment and decomposes readily
Solution Approach 1:
The patent uses a composite structure combining silicate matrix with sulfate coating. The silicate matrix provides stability and resistance to electron beam bombardment, while the sulfate coating maintains the desired phosphor properties. This composite approach resolves the contradiction by achieving both manufacturing feasibility and enhanced reliability.
Solution Approach 2:
The patent changes the chemical composition parameters by using silicate-based matrix instead of sulfide-based matrix, and by controlling the ratio of RE elements (x=0.01-0.3). This parameter change fundamentally improves the stability under electron beam bombardment while maintaining manufacturability through established ceramic processing techniques.
2Quantity of substance
If conventional sulfide-based phosphor powder is used, then the material can be produced cost-effectively, but luminous efficiency decreases due to decomposition and gas generation
Solution Approach 1:
The patent converts the harmful effect of electron beam bombardment (which causes decomposition in sulfide materials) into a beneficial process by using silicate matrix that withstands such bombardment. The stable silicate structure prevents decomposition and gas generation, thereby maintaining high luminous efficiency and reducing energy loss.
Solution Approach 2:
The composite silicate-sulfate structure allows the material to maintain high luminous efficiency by preventing the decomposition that occurs in pure sulfide-based materials. The silicate matrix provides structural stability while the sulfate coating preserves the phosphor's light-emitting properties.
3Ease of manufacture
If conventional sulfide-based phosphor powder is used, then the material can be manufactured with standard processes, but the cathode ability to emit electrons is reduced due to poisonous gas generation
Solution Approach 1:
The patent eliminates the harmful gas generation (H2S) by changing the matrix material from sulfide to silicate. The silicate matrix does not decompose to generate poisonous gases under electron beam bombardment, thereby protecting the cathode while maintaining ease of manufacture through standard ceramic processing.
Solution Approach 2:
By changing the chemical composition from sulfide-based to silicate-based matrix, the patent fundamentally alters the decomposition behavior. This parameter change prevents the generation of poisonous gases while maintaining manufacturability through established ceramic technology.
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 core-shell structured silicate luminescent material exhibits enhanced stability and luminous efficiency, suitable for use in field emission light source devices, with improved resistance to electron beam bombardment and uniform morphology.
Implementation Method 1
mixing 10 to 20 parts by volume of water, 15 to 50 parts by volume of anhydrous ethanol and 1 to 7 parts by volume of ammonia water, followed by dropwisely adding 0.5 to 3 parts by volume of tetraethylorthosilicate under stirring, stirring to react for 2 h to 6 h
Implementation Method 2
stirring to react for 2 h to 6 h further, removing impurities after being separated by centrifugation
Implementation Method 3
subjecting the same to a water bath at 50° C. to 90° C., which the pH of the resulting mixture was adjusted to 1 to 6, followed by dropwisely adding tetraethylorthosilicate to give the resulting mixture
Implementation Method 4
removing impurities after being separated by centrifugation
Implementation Method 5
calcined in air or under a reducing atmosphere, to give the core-shell structured silicate luminescent material after cooling
Data Source
AI summary
A core-shell structured silicate luminescent material and a preparation method thereof. The molecular formula of the luminescent material is: MLn1-xSiO4:xRE@SiO2; where @ represents a coating, where M is one or two elements among Li, Na, and K, where Ln is one or two elements among Y, Sc, Lu and La, where the value of x is 0<x≦0.6; and where RE is one, two, or three elements among Tb, Gd, Sm, Eu, Dy, Ce and Tm. The compositions of the luminescent material are all chemicals of increased chemical stability, and, when subjected to electron beam bombardment for an extended period, provide a stable matrix and do not decompose easily.