Spectroscopic characterization of photoinducedMn5+ions inYAlO3

We have spectroscopically studied the photoinduced color center in ${\mathrm{M}\mathrm{n}:\mathrm{Y}\mathrm{A}\mathrm{l}\mathrm{O}}_{3},$ the promising material for holographic data storage. We have proved that grayish-bluish coloration in photoexposed ${\mathrm{M}\mathrm{n}:\mathrm{Y}\mathrm{A}\mathrm{l}\mathrm{O}}_{3}$ is due to ${\mathrm{Mn}}^{5+}$ ions in octahedral sites. We assign the main features observed in the absorption and emission spectra of photodarkened ${\mathrm{M}\mathrm{n}:\mathrm{Y}\mathrm{A}\mathrm{l}\mathrm{O}}_{3}$ to the ${}^{1}{T}_{2}{(t}_{2}^{2}),$ ${}^{3}{T}_{2}{(t}_{2}e),$ ${}^{3}{T}_{1}{(t}_{2}e),$ ${}^{1}{A}_{1}{(t}_{2}^{2}),$ and ${}^{3}{A}_{2}{(e}^{2})$ excited states of ${\mathrm{Mn}}^{5+}.$ We show that ${\mathrm{Mn}}^{5+}$ ions can be stabilized in ${\mathrm{M}\mathrm{n}:\mathrm{Y}\mathrm{A}\mathrm{l}\mathrm{O}}_{3}$ codoped with Ca ions and in the crystals grown in reducing atmosphere and subsequently annealed in air at 310--460 \ifmmode^\circ\else\textdegree\fi{}C.