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The Role of Aluminium Source (Al2O3/AlN) in the Synthesis of the Ca-α-SiAlON:Eu2+ Phosphor

The purpose of the presented research was to compare the effect of changing the aluminium source in the mixture of initial powders on the properties of the final phosphor powder of Ca – α-SiAlON doped with Eu2+. The phosphor composition was designed as Eu0,048Ca0,752Si9,6Al2,4O0,8N15,2 and it was prepared by the solid state reaction in a temperature range of 1450-1650 °C. AlN and/or η-Al2O3 powders were used as a source of aluminium. It has been found that presence of aluminium nitride or oxide in the mixture of initial materials significantly changed the course of α-sialon formation, chemical composition of that solid solution and the resultant photoluminescence properties. It has been established that a small amount of η-Al2O3 with a suitable carbon addition was profitable for liquid formation and enhanced crystallization of Ca,Eu-α-sialon. The excessive oxide-rich liquid at reaction temperature led to sintering of phosphor particles and decreased emission intensity while lack of sufficient amount of liquid (nitrogen-rich starting composition) resulted in AlN presence and considerably reduced emission intensity of this phosphor.