Eu-Activated β-Sialon Phosphor Particles for Reduced Grain-Boundary Absorption
Solution Overview
Problem
Existing Eu-activated β-sialon phosphors exhibit uneven Eu distribution in grain boundaries, leading to unintended light absorption and reduced internal quantum efficiency.
Innovation Solution
The development of β-sialon phosphor particles with controlled Eu and oxygen content ratios at grain boundaries, achieved by adding titanium oxide during annealing, to ensure uniform Eu distribution and minimize unintended light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional heat treatment methods are used to produce Eu-activated β-sialon phosphor, then the phosphor can be manufactured, but uneven Eu distribution occurs at grain boundaries leading to reduced internal quantum efficiency
Solution Approach 1:
The patent applies parameter changes by modifying the oxygen content ratio at grain boundaries relative to the crystal interior. Specifically, the oxygen content at grain boundaries is controlled to be 0.03 to 3 times that of the crystal interior, which optimizes Eu distribution and prevents unintended light absorption, thereby improving internal quantum efficiency
Solution Approach 2:
The patent implements local quality by creating distinct oxygen concentration zones: the grain boundary region has a controlled oxygen content ratio (0.03 to 3 times) compared to the crystal interior. This localized oxygen distribution control ensures uniform Eu incorporation at grain boundaries while maintaining the overall crystal structure, resolving the uneven Eu distribution problem
2Illumination intensity
If Eu content is increased to enhance green light emission, then emission intensity improves, but unintended light absorption increases due to Eu aggregation at grain boundaries
Solution Approach 1:
The patent uses parameter changes by controlling the oxygen content ratio at grain boundaries (0.03 to 3 times the crystal interior oxygen content). This parameter optimization prevents Eu aggregation at grain boundaries, allowing higher Eu content to be incorporated without causing unintended light absorption, thus enhancing green light emission intensity
Solution Approach 2:
The patent converts the potentially harmful effect of grain boundaries (which normally cause Eu aggregation and light absorption losses) into a beneficial feature. By controlling oxygen content at grain boundaries to be 0.03 to 3 times that of the interior, the grain boundaries become favorable sites for uniform Eu distribution, transforming them from defect sources into emission-enhancing regions
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 solution results in β-sialon phosphors with enhanced internal quantum efficiency and improved light emission characteristics.
Implementation Method 1
a light-emitting element that emits primary light is combined with a phosphor that absorbs primary light to emit secondary light
Implementation Method 2
A phosphor containing Eu2+ in a β-sialon crystal structure (Eu-activated β-sialon phosphor) that is excited by, for example, blue light to emit green light
Data Source
AI summary
Eu-activated β-sialon phosphor particles having a grain boundary. In a cross-section of the particles including the grain boundary, when line analysis is linearly performed on elemental compositions of the grain boundary and both sides of the grain boundary in a direction perpendicular to the grain boundary at a depth of 200 nm from a portion of surfaces of the particles where the grain boundary is present, on a line segment on which the line analysis is performed, a value of NEu/N′Eu is less than or equal to 3.00, where (i) NEu represents an Eu content at a point P of the grain boundary having a peak of the Eu content and (ii) N′Eu represents an Eu content at a point Q at a distance of 50 nm from the point P.