The synthesis and characterization of rare-earth doped cost effective Beta-SiAlON phosphor powders

The light emitting diodes (LEDs), which are a kind of solid-state lighting systems, are called next generation lighting systems due to their oustanding properties that are low energy consumption, long service life, high impact and vibration resistance, infrared and ultraviolet radiation-free, eco friendly. Recently, SiAlON phosphor powders has been begun to preferred in the LED application areas. Because of that, various rare earth (RE) elements' atoms, such as Eu, Yb, Ce, Tb, Sm and Pr can be incorporated into a number of interstitial sites existing in β-SiAlON crystal structures due to Al and O substitution. In this way, it was discovered that, RE elements' atoms, located within the lattice structure, show excellent emission between a wide wavelength range of the electromagnetic spectrum (400-700nm) depending on electronic transition (4f5d) as a result of ultraviolet and/or blue light excitation. However, because of it is produced at high temperature by utilizing such methods GPS (Gas Pressure Sintering), HP (Hot Pressing), in addition to using high quality raw metarials. The aim of this thesis, is to synthesize, for the first time in the literature, RE activated β-SiAlON phosphor powders, having a broad wavelength emission to be used in LED applications as a low-cost high-technology materials, derived from naturally occurring kaolin raw materials via CRN technique. phase composition and quantitative analysis of β-SiAlON phosphor powders were been determined by XRD and Rietveld methods. The photoluminescence properties of synthesized SiAlON phosphors were been performed by florescence spectrometer using excitation and emission wavelength coming from samples. Also, microstructural examinations were been carried out with a scanning electron microscope (SEM) and transmission electron microscopy (TEM)-based analytical (energy dispersive X-ray (EDX)) techniques. When the obtained data were evaluated for each doping powder, single phase Yb+2, Sm+2 and Ce+3 doped β-SiAlON been attained, β-SiAlON:Yb+2 powder exhibited a wide range of broadcast spectrum between 520-570 nm corresponding to green and greenish yellow, β-SiAlON:Sm+2 exhibited red powder wide range of broadcast spectrum between 645-700 nm, lastly β-SiAlON:Ce+3 powder showed a large blue broadcast spectrum between 460-510 nm.