LiBa2AlSi7N12 Phosphor Phase Control for Luminescence
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Solution Overview
Problem
The luminescence characteristics of LiBa2AlSi7N12-based phosphors, as disclosed in Patent Document 1, have room for improvement due to potential degradation from subphases generated during the manufacturing process.
Innovation Solution
By controlling the abundance ratio of a specific heterophase to the main phase in the LiBa2AlSi7N12-based phosphor, using the index I2/I1 from X-ray diffraction patterns, the luminescence characteristics can be enhanced, with I1 and I2 satisfying 0<I2/I1≤0.050.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LiBa2AlSi7N12-based phosphor is manufactured using conventional firing processes, then the phosphor can be produced with standard manufacturing procedures, but subphases are generated that degrade the luminescence characteristics
Solution Approach 1:
The patent applies parameter changes by precisely controlling the firing temperature (1700-2000°C) and atmosphere (nitrogen or vacuum) to suppress subphase generation. By optimizing these physical parameters, the main phase LiBa2AlSi7N12 is stabilized while minimizing harmful subphases, thus improving luminescence characteristics without fundamentally changing the manufacturing process flow
Solution Approach 2:
The patent employs composite material strategy by using a multi-component raw material system (Li3N, Ba2SiO2N2, AlN, Si3N4, Eu2O3) that reacts to form the desired LiBa2AlSi7N12 phase. The specific composition ratios and the presence of Eu activator create a composite structure where the main phase provides excellent luminescence while controlled subphases are minimized through proper formulation
2Quantity of substance
If the abundance ratio of heterophase to main phase is increased, then more subphase is present in the phosphor, but the luminescence characteristics are enhanced by appropriately controlling this ratio
Solution Approach 1:
The patent uses X-ray diffraction peak intensity ratio (I2/I1) as a quantitative parameter to control and evaluate the heterophase abundance. By setting this ratio to 0.050 or less, the patent establishes a precise parameter threshold that ensures excellent luminescence characteristics while allowing controlled presence of heterophase
Solution Approach 2:
The patent implements feedback control by using X-ray diffraction analysis to measure the I2/I1 ratio and adjusting the firing conditions accordingly. This quality control mechanism allows real-time evaluation and adjustment of phase composition to maintain optimal luminescence characteristics
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 approach results in a phosphor with excellent luminescence characteristics, which can be stably evaluated and enhanced by setting the I2/I1 index to a predetermined value or less, leading to improved performance in light emitting devices.
Implementation Method 1
a phosphor containing an inorganic compound in which Eu as an activator is solid-soluted in an inorganic crystal having a crystal represented by LiBa2AlSi7N12
Implementation Method 2
Eu3+ has a 4f-4f transition that emits yellow light
Implementation Method 3
in an X-ray diffraction pattern of the phosphor measured using a Cu-Kα ray
Implementation Method 4
when a peak maximum intensity of a peak which is present at a position where a diffraction angle 2θ is in a range of 31.3° or more and 31.6° or less is I1
Data Source
AI summary
A phosphor of the present invention is a phosphor containing an inorganic compound in which Eu as an activator is solid-soluted in an inorganic crystal having a crystal represented by LiBa2AlSi7N12 or the same crystal structure as the crystal represented by LiBa2AlSi7N12, in which in an X-ray diffraction pattern of the phosphor measured using a Cu-Kα ray, I1 and I2 satisfy 0<I2/I1≤0.050 when a peak maximum intensity of a peak which is present at a position where a diffraction angle 2θ is in a range of 31.3° or more and 31.6° or less is I1, and a peak maximum intensity of a peak which is present at a position where a diffraction angle 2θ is in a range of 29.8° or more and 30.6° or less is I2.