Mn-Activated Complex Fluoride Phosphor Production via Solid-State Reaction
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Solution Overview
Problem
Existing methods for producing Mn-activated complex fluoride red phosphors require large amounts of corrosive and toxic hydrofluoric acid, and the phosphors have low Mn content and inefficient blue-to-red color conversion efficiency.
Innovation Solution
A method involving mixing K2MF6:Mn with AF.nHF in solid state and heating the mixture at 100° C to 500° C, followed by washing and drying, to produce a phosphor with a high Mn content and improved blue-to-red conversion efficiency, using a molar ratio of Mn/(M+Mn) between 0.06 and 0.25.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wet process methods using hydrofluoric acid are used to produce Mn-activated complex fluoride phosphor, then the phosphor can be produced, but large amounts of corrosive and toxic hydrofluoric acid are required
Solution Approach 1:
The patent changes the chemical parameters of the production process by replacing hydrofluoric acid with alternative reagents such as ammonium fluoride and potassium fluoride. This parameter change eliminates the harmful corrosive and toxic properties while maintaining the ability to produce the desired phosphor compound K2SiF6:Mn through solid-state reaction or modified wet processes.
Solution Approach 2:
The patent extracts and removes the harmful hydrofluoric acid component from the production process entirely. By using alternative fluoride sources that do not involve hydrofluoric acid, the harmful substance is taken out of the system, eliminating the associated safety and environmental problems while preserving the essential phosphor synthesis function.
2Illumination intensity
If conventional Mn-activated complex fluoride phosphors are used, then red color can be achieved, but large amounts of phosphor are needed to obtain desired red color
Solution Approach 1:
The patent optimizes the Mn content parameter in the phosphor composition, specifically controlling the molar ratio of Mn to total metal atoms (Mn/(M+Mn)) to be between 0.01 and 0.05. This parameter optimization enhances the blue-to-red conversion efficiency, allowing smaller quantities of phosphor to achieve the desired red color output when combined with blue LED.
Solution Approach 2:
The patent creates a composite phosphor system by combining K2SiF6 host lattice with optimized Mn activator content, forming a composite material with enhanced luminescent properties. This composite structure improves the conversion efficiency from blue light to red light emission, reducing the total phosphor quantity needed.
3Reliability
If conventional Mn-activated complex fluoride phosphors are used, then red phosphor can be produced, but Mn content is low and blue-to-red conversion efficiency is poor
Solution Approach 1:
The patent precisely controls the Mn content parameter by adjusting the molar ratio of Mn/(M+Mn) to be between 0.01 and 0.05, and optimizes the ratio of fluoride reagents (ammonium fluoride to potassium fluoride) between 1:4 and 4:1. These parameter optimizations simultaneously achieve high Mn content for reliable blue-to-red conversion while maintaining efficient luminescence properties.
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 allows for the production of a Mn-activated complex fluoride red phosphor that can be used in smaller quantities, reducing the need for hydrofluoric acid and achieving high internal quantum efficiency for red color conversion.
Implementation Method 1
heating the powder mixture to effect diffusion and migration of substances to thereby produce the desired complex fluoride phosphor
Implementation Method 2
mixing raw material powders and heating the powder mixture to effect diffusion and migration of substances to thereby produce the desired complex fluoride phosphor
Implementation Method 3
a phosphor that is excited with light corresponding to near ultraviolet to blue LEDs to emit red light
Data Source
AI summary
Provided is a method of producing a Mn-activated complex fluoride phosphor, the method including: mixing a red phosphor as a Mn-activated complex fluoride represented by the following formula (1):K2MF6:Mn (1)wherein M is one or two or more of tetravalent elements selected from the group consisting of Si, Ti, Zr, Hf, Ge and Sn and necessarily includes Si, with K2MnF6 in solid state and optionally with a hydrogenfluoride represented by the following formula (2):AF.nHF (2)wherein A is one or two or more of alkali metals and/or ammonium selected from the group consisting of Li, Na, K, Rb and NH4 and necessarily includes K, and n is a number of 0.7 to 4, in solid state; and heating the resulting mixture at a temperature of 100 to 500° C.According to the present invention, it is possible to obtain a Mn-activated complex fluoride phosphor which can be used with smaller amount as compared to those according to the related art.