Short-Wavelength SiAlON Phosphor for Color Rendering
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Solution Overview
Problem
Conventional SiAlON phosphors experience a decrease in color reproducibility and color rendering index due to their emission at longer wavelengths, which affects their performance in white light emitting devices.
Innovation Solution
A short-wavelength SiAlON phosphor is developed, represented by formulas SrySi(6−z)AlzOzN(8−z):Rex, SryBamSi(6−z)AlzOzN(8−z):Rex, and SrySi(6−z)AlzOzN(8−z):Rex, with specific rare-earth elements and precursors, achieving a peak emission wavelength of 525 nm to 537 nm by adjusting strontium, barium, and aluminum concentrations, and sintering conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional SiAlON phosphors are used, then they can be excited by ultraviolet or blue light to emit yellow light, but they emit at longer wavelengths causing decrease in color reproducibility and color rendering index
Solution Approach 1:
The invention changes the chemical composition parameters of the SiAlON phosphor by introducing strontium (Sr) and barium (Ba) dopants with specific concentration ranges (0.01-0.5 mol) to shift the emission wavelength to 525-537 nm, thereby improving color rendering properties while maintaining excitation characteristics
Solution Approach 2:
The invention creates a composite phosphor material combining SiAlON host lattice with rare-earth activators (Eu, Ce, Pr, Nd, Sm, Tb, Dy, Ho, Er, Tm, Yb) and alkaline earth metal dopants (Sr, Ba), achieving synergistic effects that enable short-wavelength emission with improved color reproducibility and rendering index
2Illumination intensity
If high aluminum concentration is used to achieve short wavelength emission, then color rendering improves, but manufacturing complexity increases due to precise composition control requirements
Solution Approach 1:
The invention establishes specific parameter ranges for aluminum concentration (0.50-1.0 mol) and dopant concentrations (Sr: 0.01-0.5 mol, Ba: 0.003-0.125 mol) to achieve short-wavelength emission, providing clear manufacturing guidelines that balance performance with production feasibility
Solution Approach 2:
The invention uses strontium and barium as intermediary dopants that facilitate the formation of short-wavelength emission centers within the SiAlON matrix, enabling wavelength tuning without requiring excessively high aluminum concentrations that would complicate manufacturing
3Reliability
If sintering is performed at high temperature to achieve desired crystal structure, then phosphor performance improves, but energy consumption and production cost increase
Solution Approach 1:
The invention modifies the sintering process parameters by introducing dopants that lower the required sintering temperature, allowing the phosphor to achieve desired crystal structure and performance at reduced energy consumption while maintaining structural integrity
Solution Approach 2:
The invention uses rare-earth elements and alkaline earth metal dopants as intermediaries that facilitate crystal formation and phase stability at lower sintering temperatures, reducing the energy input required while maintaining high-quality crystal structure
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 phosphors emit light at a short wavelength, preventing a decrease in color reproducibility and color rendering index, enhancing light emitting efficiency and stability.
Implementation Method 1
the phosphor is excited by an excitation source having high energy, for example, vacuum ultraviolet rays, ultraviolet rays, electron beams, and blue light
Implementation Method 2
This phosphor may be prepared by mixing proper amounts of precursor materials obtained from powders of silicon nitride, aluminum nitride, calcium carbonate (CaCO3), and europium oxide as starting materials and sintering the mixture at a high temperature under a nitrogen atmosphere
Data Source
AI summary
The fluorescent substance according to one embodiment of the present invention has the following compositional formula (1): [Compositional formula 1] SrySi(6−z)AlzOzN(8−z):Rex. Here, x, y and z are respectively 0.005≦x≦0.05, 0.05≦y≦0.5, 0.001≦z≦0.50, and Re is a rare earth element. As a result, the fluorescent substance according to one embodiment of the present invention can exhibit a short wavelength of between 525 nm and 537 nm when the concentration of strontium is between 0.05 moles and 0.5 moles. Also, the fluorescent substance can exhibit a short wavelength of between 525 nm and 537 nm by the addition of barium in a range of between 0.003 moles and 0.125 moles when the concentration of aluminium is high. Also, the fluorescent substance can exhibit a short wavelength of between 525 nm and 537 nm by adjusting the oxygen concentration by the addition not only of AlN but also of Al2O3 as an aluminium precursor when the concentration of aluminium is high. Ultimately, since the fluorescent substance according to one embodiment of the present invention can exhibit a short wavelength of between 525 nm and 537 nm, it is possible to prevent dropoff in colour reproduction and the colour rendering index.