Aluminate Phosphor Agglomerates With Controlled Particle Size
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Solution Overview
Problem
Existing fluorescent coatings for display screens and lighting are costly due to the high price of phosphors, and there is a lack of methods to produce smaller phosphor particles and larger alumina particles that enhance efficiency and cost-effectiveness.
Innovation Solution
A process is developed to prepare aluminate phosphors in the form of agglomerates with an average size of approximately 10µm, composed of particles between 0.25 and 1.5µm, using ammonium alum and rare-earth additives, followed by calcination, sieving, and grinding steps to achieve smaller and more efficient phosphor particles, and alpha alumina with a size between 0.3µm and 2µm for improved light reflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phosphor particles with smaller radii (0.4μm to 1.2μm) and alumina particles with larger grain radii (>0.6μm) are used, then coating efficiency and cost optimization are improved, but manufacturing difficulty increases as such particles were not commercially available
Solution Approach 1:
The invention changes the particle size parameters of both phosphor and alumina to optimize coating performance. Specifically, phosphor particles are reduced to radii of 0.4μm to 1.2μm while alumina particles are increased to radii greater than 0.6μm, creating an optimized size ratio that improves light reflection and coupling efficiency in the fluorescent coating
Solution Approach 2:
The invention replaces expensive commercial phosphor particles with smaller, more efficiently packed particles that provide better performance at lower cost. The theoretical study showed that smaller phosphor radii could achieve optimization, and this patent realizes that by developing a practical manufacturing approach for these smaller particles
2Loss of energy
If phosphor particles with smaller radii are used to optimize coating efficiency, then light reflection and coupling efficiency are improved, but the cost of phosphor production and processing increases
Solution Approach 1:
The invention optimizes the particle size parameter of phosphor to radii of 0.4μm to 1.2μm, which improves light reflection and coupling efficiency in the fluorescent coating. This parameter change allows better utilization of ultraviolet light conversion while reducing the overall phosphor content needed in the coating
Solution Approach 2:
The invention creates a composite fluorescent coating material combining phosphor particles with alumina particles in an optimized size ratio. The alumina particles with radii greater than 0.6μm serve as reflectors and structural support, while the smaller phosphor particles provide efficient light conversion, creating a synergistic composite material that improves overall performance
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 process reduces the cost of fluorescent coatings by optimizing phosphor particle size and enhancing light reflection, leading to more efficient ultraviolet light coupling and visible light production.
Implementation Method 1
gamma alumina obtained by the alum route, a sintering agent and alpha alumina seeds are mixed, the mixture is calcined in a furnace at a temperature between 1150°C and 1400°C
Implementation Method 2
the calcined mixture is ground, the ground mixture is passed through a non-contaminating sieve material screen between 150μm and 250μm
Data Source
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AI summary
The present invention relates to a process for preparing an aluminate phosphor in the form of agglomerates with an average size of approximately 10 µm, these agglomerates being composed of particles with an average size between 0.25 and 1.5 µm, by means of alum, comprising the following steps: • mixing ammonium alum with at least one rare-earth additive, • calcining this mixture at a first temperature between 1100°C and 1200°C, in particular 1150°C, for a duration between 1 and 2 hours, in particular 1.5 hours, • passing the calcined mixture through a non-contaminating sieve screen with a mesh size between 150 µm and 250 µm, in particular 200 µm, • grinding the calcined and sieved mixture, • passing the ground mixture through a non-contaminating sieve screen between 150µm and 250µm, particularly 200µm, • this crushed and sieved mixture is calcined at a second temperature between 1300°C and 1400°C,in particular 1350°C for a period of between 3 and 5 hours, in particular 4 hours, • the result is ground, • the ground mixture is passed through a non-contaminating sieve screen with a mesh size between 150µm and 250µm, in particular 200µm.