Nanoscale Phosphor Synthesis via RF Plasma Dissociation
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Solution Overview
Problem
Current methods for producing nanoscale phosphor particles with high internal quantum efficiency (IQE) face challenges due to surface defects and the difficulty in achieving particle sizes below 200 nm without compromising IQE, as grinding methods introduce defects and bottom-up methods result in decreased IQE with smaller particle sizes.
Innovation Solution
A method involving passing a carrier fluid with phosphor precursors through a reactive field at temperatures greater than 3000 K to dissociate and nucleate phosphor particles, using RF plasma to create nanoscale phosphor particles with high IQE and narrow size distribution, and supplying a quenching gas to control particle formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If bottom-up methods are used to synthesize nanoscale phosphor particles, then particle size can be reduced to nanoscale, but internal quantum efficiency decreases due to increased surface atoms
Solution Approach 1:
The patent changes the synthesis parameters by using thermal plasma at temperatures above 3000K to dissociate precursor molecules and form nanoscale phosphor particles. This parameter change enables controlled nucleation and growth that minimizes surface defects while maintaining nanoscale dimensions, resolving the contradiction between small particle size and high IQE
Solution Approach 2:
The patent utilizes phase transitions in the plasma state to achieve high-energy dissociation of precursors followed by controlled condensation into nanoscale particles. The plasma phase provides sufficient energy to break chemical bonds and form nuclei, then rapid cooling causes condensation into uniform nanoscale particles with controlled surface properties, maintaining high IQE
2Length of moving object
If grinding methods are used to reduce phosphor particle size, then particle size decreases, but surface defects increase which negatively affects internal quantum efficiency
Solution Approach 1:
The patent replaces the mechanical grinding system with a thermal plasma system. Instead of mechanically crushing particles which creates surface defects, the plasma method uses thermal energy to dissociate precursors and form particles from the molecular level, resulting in defect-free surfaces and high IQE
Solution Approach 2:
The patent changes from mechanical parameters (grinding force, duration) to thermal parameters (plasma temperature, residence time). By controlling plasma temperature above 3000K and residence time, the process achieves nanoscale particle formation without mechanical stress, eliminating surface defects that would otherwise reduce IQE
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 achieves nanoscale phosphor particles with average IQE of at least 40%, maintaining high efficiency even at sizes below 200 nm, and produces particles that are substantially free of impurities with a narrow size distribution, comparable to micron-sized phosphor particles.
Implementation Method 1
passing a carrier fluid with phosphor precursors through a reactive field at temperatures greater than 3000 K to dissociate and nucleate phosphor particles
Implementation Method 2
using RF plasma to create nanoscale phosphor particles with high IQE
Implementation Method 3
supplying a quenching gas to control particle formation
Data Source
AI summary
Described herein are batches of nanoscale phosphor particles having an average particle size of less than about 200 nm and an average internal quantum efficiency of at least 40%. The batches of nanoscale phosphor particles can be substantially free of impurities. Also described herein are methods of manufacturing the nanoscale phosphor particles by passing phosphor particles through a reactive field to thereby dissociate them into elements and then synthesizing nanoscale phosphor particles by nucleating the elements and quenching the resulting particles.