Nitride Phosphor Cerium Surface Enrichment

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Solution Overview

Problem

Existing phosphors used in light source devices for image projection devices have limitations in achieving high output characteristics and emission efficiency.

Innovation Solution

A method for producing a nitride phosphor involving a mixture of a first nitride with a crystal structure similar to CaAlSiN3 and a cerium source, followed by heat treatment at 1,300° C. to 1,900° C. to obtain a second nitride with enhanced cerium content, particularly at the surface, improving absorption of excitation light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional phosphors are used in light source devices, then the device can operate, but the output characteristics and emission efficiency are limited

Engineering Contradiction:

Improvelight outputVSAvoidemission efficiency

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the chemical composition parameters by incorporating cerium into the CaAlSiN3 host crystal structure, forming Ce-doped CaAlSiN3 phosphor. This compositional parameter change results in improved emission efficiency and higher light output, resolving the contradiction between productivity and reliability.

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If heat treatment is performed at high temperature (1,300°C to 1,900°C), then cerium content increases and absorption of excitation light improves, but energy consumption increases

Engineering Contradiction:

Improveemission intensityVSAvoidenergy consumption

Core Design Contradiction:

Illumination intensityVSUse of energy by moving object

Solution Approach 1:

The patent optimizes the heat treatment temperature parameter within the specific range of 1,300°C to 1,900°C to achieve sufficient cerium incorporation and surface enrichment. This controlled parameter change enables improved emission intensity while managing energy consumption, as the treatment can be optimized to use the minimum necessary temperature for the desired effect.

Inventive Principle:

Principle #35Parameter changes

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 resulting nitride phosphor exhibits increased emission intensity corresponding to excitation energy, even at high energy excitation, due to the higher cerium content near the surface, leading to improved light output characteristics.

Implementation Method 1

performing a heat treatment of the mixture at a temperature of 1,300° C. to 1,900° C. to obtain a second nitride

Methodology Applied

Scientific EffectHeat treatment: Heat Treatment

Implementation Method 2

heat treatment at 1,300° C. to 1,900° C. to obtain a second nitride with enhanced cerium content, particularly at the surface

Methodology Applied

Scientific EffectThermal diffusion: Diffusion

Implementation Method 3

The resulting nitride phosphor exhibits increased emission intensity corresponding to excitation energy

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentUS12269978B2Nitride phosphor and method for producing same

Publication Date: 2025.04.08 NICHIA CORP

AI summary

Provided a method for producing a nitride phosphor. The method includes preparing a mixture that comprises a first nitride and a cerium source, the first nitride comprising, as a host crystal, a crystal having the same crystal structure as CaAlSiN3; and performing a heat treatment of the mixture at a temperature of 1,300° C. to 1,900° C. to obtain a second nitride. The first nitride comprises aluminum, silicon, nitrogen, and at least one selected from the group consisting of lithium, calcium, and strontium.