Red Phosphor Gradient Mn4+ Structure for Moisture Aging Resistance
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Solution Overview
Problem
The water resistance and luminous efficiency of K2SiF6:Mn4+ phosphors are compromised due to manganese oxidation on the surface, leading to reduced brightness and a short service cycle, and increasing the shell thickness affects blue light absorption and quantum efficiency.
Innovation Solution
A gradient distribution of activator Mn4+ concentration from the center to the surface of the red phosphor, with a manganese-free shell layer, protecting the crystal lattice and enhancing anti-aging performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shell thickness of the shell layer without Mn4+ activator doping is increased to protect the phosphor surface, then the anti-deterioration ability is improved, but the blue light absorption is affected and quantum efficiency is reduced
Solution Approach 1:
The patent applies local quality by creating a gradient distribution of Mn4+ concentration within the phosphor particle, where the core region has higher Mn4+ concentration for strong luminescence while the shell region has lower or zero Mn4+ concentration for protection. This spatial variation in composition allows different regions to fulfill different functions: the core provides luminescence efficiency while the shell provides anti-deterioration capability.
Solution Approach 2:
The patent segments the phosphor particle into distinct regions with different Mn4+ concentrations - a core region and a shell region. This segmentation allows the particle to simultaneously achieve high luminescence efficiency in the core and high anti-deterioration ability in the shell, resolving the contradiction between these two opposing requirements.
2Reliability
If a non-quaternary Mn shell structure is constructed to reduce surface manganese, then the oxidation resistance is improved, but the crystal structures of particles surface is destroyed and luminous efficiency is reduced
Solution Approach 1:
The patent uses local quality by creating a gradient Mn4+ distribution where the shell region has reduced Mn4+ concentration to prevent oxidation while the core region maintains high Mn4+ concentration for luminescence. This avoids the need for post-synthesis reduction treatments that would destroy the crystal structure.
Solution Approach 2:
The patent applies preliminary action by incorporating the gradient Mn4+ distribution during the synthesis process itself, rather than performing subsequent reduction treatments. This preliminary structuring prevents oxidation before it occurs while maintaining the integrity of the crystal lattice throughout the particle.
3Ease of manufacture
If the concentration of activator Mn4+ is uniformly distributed throughout the particle, then the manufacturing process is simple, but the anti-aging ability is poor due to surface manganese oxidation
Solution Approach 1:
The patent applies local quality by creating spatial variation in Mn4+ concentration, with the core having high concentration for luminescence and the shell having low or zero concentration for protection. This gradient structure can be achieved through controlled synthesis methods that deposit Mn4+ preferentially in the core region.
Solution Approach 2:
The patent segments the particle into core and shell regions with different Mn4+ concentrations, allowing the core to provide luminescence function while the shell provides protection function. This segmentation resolves the contradiction between manufacturing simplicity and anti-aging ability.
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 anti-aging ability and luminous efficiency of the phosphor are improved by buffering water vapor erosion, extending the service cycle and maintaining luminescence performance.
Implementation Method 1
a concentration of activator Mn4+ in a radial direction from a center of a particle of the red phosphor to a surface of the particle of the red phosphor is reduced in form of a gradient distribution, so as to buffer erosion of water vapor on the phosphor powder
Implementation Method 2
the Mn4+ existing on the surface of the phosphor particles is exposed to moisture in the air, which would be oxidized to dark manganese oxides
Implementation Method 3
K2SiF6:Mn4+ fluoride fluorescent material
Data Source
AI summary
The present application discloses a red phosphor, and a preparation method and an application thereof and relates to the field of luminescent material technology. The chemical composition of the red phosphor is A2M(1-x)F6:xMn4+. The A is selected from at least one of alkali metal elements, and the M is selected from at least one of IVA group elements or a Ti element and a value range of the x is 0<x≤0.05. The red phosphor is granular; and a concentration of tetravalent manganese ions in a radial direction from a center of a particle of the red phosphor to a surface of the particle of the red phosphor decreases gradually. In the present application, the concentration of the activator Mn4+ in a radial direction from the center of the particle of the red phosphor to its surface is set to a descending gradient distribution to buffer the phosphor powder from the erosion of water vapor, thereby improving its anti-aging performance and prolonging the service life.