Oxide-Coated Fluoride Phosphor for Moisture-Stable Light Emission
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Solution Overview
Problem
The reliability of light-emitting devices containing a fluoride phosphor and a resin can be compromised by environmental factors, leading to instability and reduced performance.
Innovation Solution
A fluoride phosphor with a specific composition, including elements like Si, Al, Ti, Zr, Sn, and Zn oxides, and rare earth phosphates, is developed to enhance the reliability of light-emitting devices by improving moisture and heat resistance, and a method for manufacturing this phosphor involves coating fluoride particles with these oxides and phosphates in a controlled manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fluoride phosphor is used in light-emitting devices, then high color purity and narrow emission peak are achieved, but reliability decreases under environmental conditions
Solution Approach 1:
The patent applies composite materials by combining fluoride phosphor particles with multiple protective coatings including oxide layers (SiO2, Al2O3, TiO2, ZrO2, SnO2, ZnO) and rare earth phosphate layers. This multi-layer composite structure maintains the high color purity of the fluoride phosphor while adding environmental stability and reliability under various conditions.
Solution Approach 2:
The patent uses oxide layers and rare earth phosphate layers as intermediary protective barriers between the fluoride phosphor and the external environment. These intermediary layers prevent direct contact between the phosphor and harmful environmental factors such as moisture and heat, thereby maintaining reliability without affecting the optical properties.
2Reliability
If oxide coating is applied to fluoride phosphor, then moisture and heat resistance improve, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-coating the fluoride phosphor particles with oxide layers and rare earth phosphate layers before incorporating them into the light-emitting device. This preliminary protective treatment ensures moisture and heat resistance is built-in during manufacturing, preventing degradation during device operation without requiring complex post-manufacturing processes.
Solution Approach 2:
The patent controls the thickness and composition parameters of the oxide and phosphate coatings to optimize both protective performance and manufacturing feasibility. By carefully adjusting coating parameters such as layer thickness and material composition ratios, the patent achieves adequate protection while maintaining manageable manufacturing complexity.
3Reliability
If multiple coating layers are applied to fluoride particles, then durability under high temperature and humidity improves, but production cost increases
Solution Approach 1:
The patent applies multi-functionality by using rare earth phosphate layers that simultaneously provide protective functions (moisture and heat resistance) and maintain optical performance. This multi-functional approach ensures durability under high temperature and humidity while avoiding the need for additional separate protective measures, thereby controlling production costs.
Solution Approach 2:
The patent uses relatively inexpensive oxide materials (such as SiO2, Al2O3, TiO2, ZrO2, SnO2, ZnO) and rare earth phosphates that provide effective protection at reasonable costs. These coating materials offer adequate durability under harsh conditions without requiring expensive specialized materials, thus maintaining cost-effectiveness.
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 coated fluoride phosphor significantly improves the reliability and durability of light-emitting devices by reducing resin degradation and maintaining luminous flux under high temperature and humidity conditions, ensuring consistent performance.
Implementation Method 1
causing the prepared fluoride particles and a metal alkoxide including at least one element selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn to come into contact with each other in a liquid medium thereby covering at least a portion of the surface of the fluoride particle with an oxide derived from the metal alkoxide
Implementation Method 2
causing the prepared fluoride particles, rare earth ions including at least one type selected from the group consisting of La, Ce, Dy, and Gd, and phosphate ions to come into contact with each other in a liquid medium thereby obtaining fluoride particles to which a rare earth phosphate is adhered
Data Source
AI summary
Provided is a fluoride phosphor that can improve reliability in a light-emitting device. The fluoride phosphor includes fluoride particles and an oxide covering at least a portion of the surface of the fluoride particles. The oxide contains at least one element selected from the group consisting of Si, Al, Ti, Zr, Sn, and Zn, and a content percentage of the oxide is in a range from 2 mass % to 30 mass %. The fluoride particles have a composition containing an element M including at least one element selected from the group consisting of Group 4 elements, Group 13 elements, and Group 14 elements, an alkali metal, Mn, and F, and when the number of moles of the alkali metal is 2, the number of moles of Mn is in a range greater than 0 and less than 0.2, the number of moles of the element M is a range greater than 0.8 and less than 1, and the number of moles of F is in a range greater than 5 and less than 7.