Nitride Oxy-Nitride Phosphor Composition for High Luminance
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Solution Overview
Problem
Current light-emitting devices using nitride type yellow phosphors have limitations in achieving high light-emitting efficiency and pseudo white color emission.
Innovation Solution
A phosphor with a specific crystal phase formula, R3−x−y−z+w2MzA1.5x+y−w2Si6−w1−w2Alw1+w2Oy+w1N11−y−w1, where R is a rare earth element, M is a metal element, and A is a bivalent metal element, with specific numerical value ranges for x, y, z, w1, and w2, is used, along with a method involving nitriding an alloy in the presence of a flux under controlled temperature and atmosphere conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional nitride type yellow phosphors are used, then color rendering properties are improved, but light-emitting efficiency deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the phosphor by introducing specific ratios of rare earth elements (La, Gd, Lu, Y, Sc), metal elements (Ce, Eu, Mn, Yb, Pr, Tb), and bivalent metal elements (Ba, Sr, Ca, Mg, Zn) in the formula R3−x−y−z+w2MzA1.5x+y−w2Si6−w1−w2Alw1+w2Oy+w1N11−y−w1. By optimizing the compositional parameters (x, y, z, w1, w2) and controlling the object color in L*a*b* color space (−20≦a*≦−2, 71≦b*), the patent achieves both good color rendering and high light-emitting efficiency, resolving the contradiction between color rendering properties and light-emitting efficiency.
2Use of energy by moving object
If cerium-activated yttrium/aluminum/garnet type phosphor is used, then light-emitting efficiency is improved, but color rendering properties deteriorate
Solution Approach 1:
The patent creates a composite phosphor material combining multiple rare earth elements (R), metal elements (M), and bivalent metal elements (A) in a nitride-oxy-nitride matrix structure. This composite approach integrates the high efficiency characteristics of cerium-activated phosphors with the superior color rendering of nitride phosphors. The specific formula R3−x−y−z+w2MzA1.5x+y−w2Si6−w1−w2Alw1+w2Oy+w1N11−y−w1 with controlled composition ratios and object color parameters achieves both high light-emitting efficiency and good color rendering properties, resolving the contradiction between these two 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 solution results in a phosphor with high luminance and luminous efficiency, enabling a light-emitting device with improved pseudo white color emission and efficiency.
Implementation Method 1
a phosphor which emits a yellow to orange light under irradiation with light from an excitation light source such as a semiconductor light-emitting element
Implementation Method 2
a method involving nitriding an alloy in the presence of a flux under controlled temperature and atmosphere conditions
Data Source
AI summary
A phosphor includes a crystal phase of a formula (Ln,Ca,Ce)3+αSi6N11. In this formula, α is from −0.1 to 1.5, inclusive. When an object color of the phosphor is expressed by the L*a*b* color system, the value of (a*2+b*2)1/2 satisfies 71≦(a*2+b*2)1/2. Also in the formula, Ln is La, Gd, Lu, Y, Sc, or any combination of these. When the phosphor is excited with light having a wavelength of 455 nm, it emits a color wherein x is from 0.400 to 0.570 inclusive, and y is from 0.420 to 0.590, inclusive, as expressed in the CIE standard coordinate system.