Synthesis and luminescence characteristics of fine-sized Ba3Si6O12N2:Eu green phosphor through spray pyrolysis using TEOS/Si3N4 mixed precursors

Abstract

Fine-sized Ba₃Si₆O₁₂N₂:Eu²⁺ phosphor powders were synthesized by spray pyrolysis using tetraethyl orthosilicate (TEOS) and Si₃N₄ nanopowder as Si precursors, and the crystallographic and luminescence characteristics were explored with changing the mole ratio of TEOS to Si₃N₄. When only Si₃N₄ was used as the Si precursor, the main phase of the resulting particles was Ba₃Si₆O₉N₄ and the Ba₃Si₆O₁₂N₂ phase was formed as an impurity phase. As the TEOS mole fraction increased as the Si precursor, the main phase changed from Ba₃Si₆O₉N₄ to Ba₃Si₆O₁₂N₂, and BaSi₂O₅ was formed as the main phase when the TEOS fraction was 80% or higher. As a result, the excitation and emission intensity were largely affected by changing the TEOS/Si₃N₄ ratio. Finally, the optimal TEOS/Si₃N₄ mole ratio was determined as 50/50 in terms of preparing Ba₃Si₆O₁₂N₂:Eu particles having the highest emission through spray pyrolysis. At the TEOS fraction of 50%, the crystallographic form and the emission properties were investigated as the calcination temperature was varied from 700 °C to 1350 °C. It was found that Ba₂Si₃O₈ is generated as an intermediate phase at a calcination temperature of lower than 1200 °C and a pure Ba₃Si₆O₁₂N₂ phase without any impurity phases was obtained at 1300 °C. Based on XRD analysis, a possible formation mechanism of Ba₃Si₆O₁₂N₂:Eu was discussed. The prepared Ba₃Si₆O₁₂N₂:Eu²⁺ powder exhibited high thermal stability with the thermal activation energy of 0.247 eV and a fine size of less than 1 μm without significant agglomeration.