Mn4+ Red Phosphor Co-Precipitation for Small Particle Size
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Solution Overview
Problem
Existing processes struggle to achieve smaller particle sizes and higher manganese content in complex fluoride phosphors activated by Mn4+, which are necessary for next-generation LED devices, due to solubility limitations and reduced quantum efficiency when synthesizing near the solubility limit of the Mn source.
Innovation Solution
A process involving the dissolution of the Mn source in HF prior to adding H2MF6, followed by rapid co-precipitation with a source of A, such as KF, to form a homogeneous solution, resulting in high-quality phosphors with smaller particle sizes and higher manganese dopant concentrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Mn source is dissolved in HF prior to adding H2MF6, then the quantum efficiency and manganese content are improved, but the process complexity increases
Solution Approach 1:
The Mn source is dissolved in HF before adding H2MF6, performing the dissolution action in advance. This preliminary action ensures complete dissolution and homogeneous distribution of Mn ions, preventing premature precipitation and ensuring high quantum efficiency and manganese content in the final phosphor product.
Solution Approach 2:
HF acts as an intermediary substance that facilitates the dissolution of the Mn source and controls the subsequent precipitation process. By using HF as a mediator, the patent achieves controlled formation of Mn4+ ions in solution, enabling high Mn content (above 1.5 wt%) while maintaining quantum efficiency above 85%.
2Adaptability or versatility
If the particle size is reduced to below 5 μm, then the suitability for next-generation LED devices is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The patent changes the chemical parameters of the synthesis process by using specific ratios of HF, H2MF6, and Mn source, along with controlled temperature and time conditions. These parameter changes enable the formation of particles with D50 size below 5 μm while maintaining narrow size distribution, making the phosphor suitable for mini-LED and micro-LED applications.
Solution Approach 2:
The patent replaces mechanical size reduction methods with a chemical precipitation approach. By controlling the chemical formation process through solution-based synthesis, the patent achieves precise particle size control below 5 μm without requiring mechanical grinding or classification, thereby reducing manufacturing complexity while achieving the desired particle size for next-generation LED devices.
3Reliability
If the manganese content is increased to above 1.5 wt%, then the color stability and quantum efficiency are improved, but the solubility limitations are exceeded
Solution Approach 1:
The patent changes the chemical environment by using HF as a dissolving agent, which alters the solubility characteristics of the Mn source. This parameter change enables the incorporation of high Mn content (above 1.5 wt%) into the phosphor structure without precipitation, while maintaining color stability and quantum efficiency through controlled solution chemistry.
Solution Approach 2:
HF serves as an intermediary that enables high Mn content incorporation by controlling the dissolution and precipitation processes. The HF-mediated process allows Mn4+ ions to be incorporated at concentrations above 1.5 wt% while maintaining color stability, overcoming the solubility limitations that would otherwise restrict Mn content.
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
This method enables the production of Mn4+ doped phosphors with particle sizes below 5 μm and manganese content above 1.5 wt%, enhancing quantum efficiency and suitability for next-generation LED applications.
Implementation Method 1
dissolution of the Mn source in HF prior to adding H2MF6
Implementation Method 2
rapid co-precipitation with a source of A, such as KF, to form a homogeneous solution
Data Source
AI summary
In one aspect, a process for preparing a Mn4+ doped phosphor of Formula I is provided Ax[MFy]:Mn4+ (I). The process includes combining a first aqueous solution including a source of Mn with a second solution including H2MF6 to form a third solution, and combining the third solution with a fourth solution including a source of A to form the Mn4+ doped phosphor, where A is Li, Na, K, Rb, Cs, or a combination thereof; M is Si, Ge, Sn, Ti, Zr, Al, Ga, In, Sc, Y, La, Nb, Ta, Bi, Gd, or a combination thereof; x is the absolute value of the charge of the [MFy] ion; and y is 5, 6 or 7. Methods, phosphors and devices are also provided.