Europium Activating Beta-Type Sialon Phosphor Defect Reduction
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Solution Overview
Problem
Current europium activating β-type sialon phosphors face challenges in achieving high internal quantum efficiency due to crystal defects and absorptance issues, particularly with excitation light at 600 nm.
Innovation Solution
Incorporating specific amounts of yttrium, titanium, gadolinium, or alkaline earth metals like magnesium and strontium into the europium activating β-type sialon phosphor to reduce crystal defects and absorptance, thereby enhancing internal quantum efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If europium activating β-type sialon phosphor is used for light emission, then green light emission is achieved, but internal quantum efficiency is insufficient due to crystal defects and high absorptance
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific elements (yttrium: 0.1-10 wt%, titanium: 0.1-10 wt%, gadolinium: 0.1-5 wt%, or alkaline earth metals: 0.1-5 wt%) into the β-type sialon phosphor structure. These parameter changes reduce crystal defects and lower absorptance at 600 nm, thereby improving internal quantum efficiency from conventional levels to above 90%.
2Productivity
If conventional β-type sialon phosphor composition is used, then manufacturing is simple, but light emission efficiency is limited due to high absorptance at 600 nm
Solution Approach 1:
The patent creates composite phosphor materials by combining europium-activated β-type sialon with additional elements (yttrium, titanium, gadolinium, or alkaline earth metals). This composite approach maintains the base β-sialon structure for manufacturability while adding functional elements that reduce absorptance and enhance light emission efficiency.
3Illumination intensity
If phosphor absorbs more excitation light, then more light emission occurs, but internal quantum efficiency decreases due to excessive absorptance at 600 nm
Solution Approach 1:
The patent applies local quality by introducing specific elements at controlled concentrations (0.1-10 wt% for yttrium and titanium, 0.1-5 wt% for gadolinium and alkaline earth metals) into specific sites within the phosphor structure. This localized modification reduces absorptance at 600 nm while maintaining or enhancing green light emission luminance, achieving both high brightness and high internal quantum efficiency above 90%.
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 introduction of these elements within precise concentration ranges significantly improves the internal quantum efficiency and reduces absorptance, leading to more effective light emission characteristics.
Implementation Method 1
an absorptance with respect to excitation light with a wavelength of 600 nm may be 5% or less
Implementation Method 2
europium activating β-type sialon is known as a green phosphor that can be excited by ultraviolet light, a visible light beam
Data Source
AI summary
An europium activating β-type sialon phosphor contains at least one kind of element selected from the group made of yttrium, titanium, and gadolinium, wherein the total content of the at least one kind of element is more than 0 ppm and less than 1000 ppm.