Luminescence Properties of Eu²⁺/Eu³⁺ Activated Barium Aluminate Phosphors with Gd³⁺ Concentration Variation

Abstract

BaAl₂O₄:Eu2⁺/Eu3⁺ (1 mol %) co-doped with varying concentrations of Gd3⁺ (1, 2, 5 and 10 mol%) were prepared by combustion synthesis method at 600°C. All the compositions were investigated for their structural and photoluminescence properties. Samples prepared in open atmosphere showed the presence of both Eu3⁺ and Eu2⁺ states which indicates the reduction of Eu3⁺ to Eu2⁺ during the preparation of these compounds. The prepared materials at 600°C showed high intense broad peaks around 498 nm corresponding to Eu2⁺ and small peaks in the red region which are attributed to the presence of Eu3⁺. In the 1000°C annealed compounds, the intensity of the peak at 498 nm got increased. The intensity of this broad band for BaAl₂O₄:Eu2⁺/Eu3⁺(1 mol%):Gd3⁺(1 mol%) was three times than that of BaAl₂O₄:Eu2⁺/Eu3⁺(1 mol%). Thus second rare earth ion (Gd3⁺) acted as a good sensitizer and enhanced the photoluminescence intensity. The XRD spectra revealed the presence of hexagonal phase of BaAl₂O₄ as main phase and a small amount of a mixed phase Ba O! 6.6 Al₂O₃. Doping of Eu3⁺, Gd3⁺ did not change the crystalline structure of barium aluminate (BaAl₂O₄).

Keywords:

• Phosphors
• Luminescence
• Combustion method
• Barium aluminate