$SrTiO_3$:Pr has been studied as a red phosphor for field emission display(FED) because of its good color purity, chemical stability in high vacuum and under high current bombardment. Regrettably it has a very poor brightness efficiency by itself. But when Al is added, its red luminescent intensity is intensified up to 100 times. The exact behavior of Al as to how it improves the luminescence of $SrTiO_3$:Pr has been of great interest.
In this study $SrTiO_3$:Pr, Al as a red FED phosphor has been investigated in order to improve the understanding on the behavior of Al in $SrTiO_3$:Pr, Al. The $SrTiO_3$:Pr were prepared by solid state reaction method. Any evident change in the XRD patterns and the lattice parameters were not found even at an Al concentration as high as about 0.4mol. per 1mol.phosphor. Red luminescence is highest at an Al concentration of about 23mol%.
By TEM image and electron diffraction study the presence of the second phase $SrAl_{12}O_{19}$ was identified in $SrTiO_3$:Pr when Al is added as much as 23mol%.
Cathodoluminescence (CL) intensities of the intentionally mixed samples of two phases $SrTiO_3$ and $SrAl_{12}O_{19}$ were compared. Some samples were prepared at different mixing fractions of $SrAl_{12}O_{19}$ and sintering temperatures. Others were prepared only by mixing without sintering. Luminescence intensities of only mixed samples decreased more considerably as mixing fraction of $SrAl_{12}O_{19}$ is increased. On the other hand, those of sintered samples in which mixing fraction of $SrAl_{12}O_{19}$ is under 1mol% increased slightly.
It seems that the mole fraction of the formed $SrAl_{12}O_{19}$ in $SrTiO_3$:Pr, Al is about 1mol% when Al is added as much as 23mol%. It is suggested from the analysis of the experimental results that most of luminescence intensity enhancement is caused by Als which enter in the $SrTiO_3$ and the small part is affected by the formed $SrAl_{12}O_{19}$
