Improvement and Practical Application of SiAlON Phosphors

Abstract

Background and Aims: SiAlON phosphors are ceramic powders that exhibit luminescent properties when doped with cations like Eu²⁺. These materials are known for their high-temperature stability and durability, making them essential components in white LEDs used for lighting and display applications. Initially, SiAlON phosphors had low luminescence efficiency, but through optimization of chemical composition and manufacturing processes, their properties have significantly improved. This document explores the development and practical applications of α- and β-SiAlON phosphors, highlighting their role in enhancing the performance of LEDs in various fields, including turn signals and LCD backlights.

Methods and Results: The development of SiAlON phosphors involved optimizing their chemical composition and refining manufacturing processes to enhance luminescent properties. For α-SiAlON phosphors, various cations like Ca²⁺ and Eu²⁺ were added to improve luminescence efficiency and stability. The manufacturing process included mixing raw materials and firing them at high temperatures (1700–1900°C) in a nitrogen atmosphere. Adjustments in the composition parameters (m and n values) led to significant improvements in fluorescence intensity and peak wavelength. For β-SiAlON phosphors, the process involved higher firing temperatures (1950–2050°C) and post-treatment methods like heat and acid treatments to enhance internal quantum efficiency. These treatments resulted in a threefold increase in fluorescence intensity compared to initial values. Additionally, the study explored the effects of precursor particle morphology, sintering kinetics, and phase purity on the final phosphor performance. The use of α-SiAlON seed particles and controlled heating rates contributed to improved crystallinity and reduced grain boundary phases, which in turn enhanced quantum efficiency. For β-SiAlON, post-synthesis annealing in argon followed by acid treatment was found to remove defect-related absorptive species, leading to brighter and more stable green emission. The improved phosphors demonstrated better performance in high-temperature and high-humidity environments, making them suitable for applications in LEDs and displays.

Conclusions(Outlooks): The advancements in SiAlON phosphors have led to significant improvements in luminescence efficiency and durability, enabling their practical application in various fields such as turn signals and LCD backlights. The ongoing research aims to further enhance these materials’ properties, making them even more suitable for high-performance lighting and display technologies. Future developments will focus on optimizing chemical compositions and refining manufacturing processes to achieve even higher efficiency and broader application potential.