Green light emission in aluminum oxide powders doped with different terbium concentrations

Abstract

Different emission intensities presented in aluminum oxide phosphors corresponding to different concentrations of doping performed with terbium are analyzed. The phosphors were synthesized by the evaporation technique and were characterized by photo and cathodoluminescence, x-ray diffraction, and EDS techniques for different incorporation percentages of terbium as dopant; they show characteristic transitions in 494, 543, 587 and 622 nm, corresponding to ${}^5$D$_4$ $\rightarrow$ ${}^7$F$_6$, ${}^5$D$_4$ $\rightarrow$ ${}^7$F$_5$, ${}^5$D$_4$ $\rightarrow$ ${}^7$F$_4$ and ${}^5$D$_4$ $\rightarrow$ ${}^7$F$_3$, respectively when they are excited with $\lambda_{\textrm{exc}} = 380$ nm wavelength at room temperature. The results of XRD show the presence of $ \alpha $-Al$_2$O$_3$ phases with peaks located at $2\theta = 25.78$, 35.34, 37.96, 43.56, 45.8, 52.74, 57.7, 61.5, 66.74, 68.44, 77.12 and 80.94, and the $ \delta $-Al$_2$O$_3$ phase $2\theta = 32.82$, 45.8, 61.36 and 66.74. These compounds were heat treated for two hours at 1100$^{\circ}$C. EDS analyzes indicate that these compounds have close to 60% oxygen around of 40% aluminum in the presence of terbium as dopant which indicates a stoichiometry close to the expected one for alumina.