Room-Temperature Phosphor Synthesis via Fluoride Concentration Control
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Solution Overview
Problem
Current methods for producing red light-emitting phosphors for white LEDs are hazardous due to the use of high-temperature hydrogen fluoride evaporation and lack a safe and efficient way to control crystal phases and produce zero phonon lines (ZPL).
Innovation Solution
A method involving chemical recrystallization using potassium hexafluorogermanate (K2GeF6) and manganese fluoride (K2MnF6 or KMnO4) in a hydrofluoric acid solution, with anhydrous ethanol added to regulate fluoride ion concentrations, allowing for the formation of red light-emitting phosphors with specific crystal phases and ZPLs at room temperature, avoiding high-temperature processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If high-temperature hydrogen fluoride evaporation is used to co-crystallize fluorides, then red light-emitting phosphors can be produced, but the process becomes dangerous and requires subsequent hydrogen fluoride recycling
Solution Approach 1:
The patent extracts the harmful hydrogen fluoride evaporation step from the synthesis process. Instead of using high-temperature HF evaporation to co-crystallize fluorides, the invention uses a low-temperature chemical reaction method where K2GeF6 and K2MnF6 react in anhydrous ethanol solution at room temperature to directly form the desired phosphor product, completely eliminating the dangerous HF handling step
Solution Approach 2:
The patent changes the reaction parameters from high-temperature physical evaporation to low-temperature chemical reaction. The synthesis is conducted at room temperature using chemical reagents (K2GeF6, K2MnF6, and anhydrous ethanol) to achieve phosphor formation without requiring high-temperature HF evaporation, thus changing the temperature and reaction mechanism parameters
2Manufacturing precision
If formulas are adjusted to make phosphors produce zero phonon line, then ZPL can be achieved, but there is still no method using chemical recrystallization to control crystal phase
Solution Approach 1:
The patent uses parameter changes in the chemical recrystallization process to control crystal phase. By adjusting the concentration ratio of K2GeF6 to K2MnF6, the amount of anhydrous ethanol added, and the reaction temperature, the invention achieves precise control over the crystal phase structure, enabling the formation of specific hexagonal phases with desired optical properties including ZPL
Solution Approach 2:
The patent introduces anhydrous ethanol as an intermediary medium for chemical recrystallization. The anhydrous ethanol serves as both solvent and reactant, facilitating the low-temperature chemical reaction between K2GeF6 and K2MnF6, and enabling precise control of crystal phase formation through its concentration and addition amount
Data Source
AI summary
The present disclosure provides a method for fabricating a phosphor. A first solution is formed by dissolving potassium hexafluorogermanate (K2GeF6) and either K2MnF6 or KMnO4 in a hydrofluoric acid solution. An anhydrous ethanol is added to the first solution to make a total concentration of fluoride ions of potassium hexafluorogermanate (K2GeF6), hydrofluoric acid, and either K2MnF6 or KMnO4 equal to or less than 48M to form a precipitate. Afterward, the precipitate is collected.