Nitride Ceramic Sintered Body for Higher Light Emission
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Solution Overview
Problem
Existing ceramic sintered bodies used in light emitting devices often suffer from reduced light emission intensity due to binder reactions with fluorescent materials, affecting their light emission characteristics.
Innovation Solution
A method for producing a ceramic sintered body using a nitride fluorescent material with a specific composition, calcined at temperatures between 1,600° C. and 2,200° C., which reduces voids and maintains the integrity of the fluorescent material's composition, enhancing light emission intensity without adverse effects on light emission characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If an oxide binder is used to form a sintered body, then the sintered body can be formed, but the binder reacts with the fluorescent material and reduces light emission intensity
Solution Approach 1:
The patent removes the oxide binder component from the sintered body formulation entirely, using only nitride fluorescent material particles. This extraction eliminates the harmful chemical reaction between oxide binders and fluorescent materials, preserving light emission intensity while still achieving sintered body formation through direct sintering of the nitride-based material.
Solution Approach 2:
The patent employs a composite sintered body structure where nitride fluorescent material particles are embedded in a nitride-based ceramic matrix. This composite approach maintains the chemical compatibility between binder and fluorescent material, preventing adverse reactions while achieving strong bonding and high light emission intensity.
2Ease of manufacture
If a fluoride inorganic binder is used, then the sintered body can be formed, but the binder reacts with the nitride fluorescent material and adversely affects light emission characteristics
Solution Approach 1:
The patent eliminates fluoride inorganic binders from the formulation, using only nitride fluorescent material and nitride-based ceramic materials. This removal prevents the harmful reaction between fluoride binders and nitride fluorescent material, ensuring reliable light emission characteristics while maintaining sintered body formation capability.
Solution Approach 2:
The patent changes the chemical composition parameters of the binder material from oxide or fluoride-based to nitride-based materials. This parameter change ensures chemical compatibility with the nitride fluorescent material, preventing adverse reactions and maintaining stable light emission characteristics throughout the device lifetime.
3Illumination intensity
If the crystallite size of the nitride fluorescent material is reduced to 550 Å or less, then light emission intensity is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the crystallite size parameter of the nitride fluorescent material to 550 Å or less, which has been determined to maximize light emission intensity. This parameter optimization balances the need for high light emission with manufacturability, as this specific crystallite size range can be achieved through controlled sintering processes while maintaining reasonable manufacturing precision requirements.
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 method results in a ceramic sintered body with improved light emission intensity and relative density, reducing light scattering and maintaining the fluorescent material's properties, suitable for use in light emitting devices.
Implementation Method 1
a light emitting device using a light emitting element such as an LED or an LD is constituted by combining a light emitting element serving as an excitation light source and a member containing a fluorescent material that absorbs a part of light emitted from the light emitting element and converts the wavelength of the light to a different wavelength
Implementation Method 2
The method results in a ceramic sintered body with improved light emission intensity and relative density, reducing light scattering and maintaining the fluorescent material's properties
Data Source
AI summary
Provided are a method for producing a ceramic sintered body having improved light emission intensity, a ceramic sintered body, and a light emitting device. The method for producing a ceramic sintered body comprises preparing a molded body that contains a nitride fluorescent material having a composition containing: at least one alkaline earth metal element M1 selected from the group consisting of Ba, Sr, Ca, and Mg; at least one metal element M2 selected from the group consisting of Eu, Ce, Tb, and Mn; Si; and N, wherein a total molar ratio of the alkaline earth metal element M1 and the metal element M2 in 1 mol of the composition is 2, a molar ratio of the metal element M2 is a product of 2 and a parameter y and wherein y is in a range of 0.001 or more and less than 0.5, a molar ratio of Si is 5, and a molar ratio of N is 8, and wherein the nitride fluorescent material has a crystallite size, as calculated by X-ray diffraction measurement using the Halder-Wagner method, of 550 Å or less, and calcining the molded body at a temperature in a range of 1,600° C. or more and 2,200° C. or less to obtain a sintered body.