Laser site-selective excitation spectroscopy ofEu3+-doped yttrium aluminum garnet

Abstract

We report the results for laser site selective excitation spectroscopy of ${\mathrm{Eu}}^{3+}$-doped yttrium aluminum garnet. We identified four primary luminescent centers (A--D) from the ${}^{7}{\stackrel{\ensuremath{\rightarrow}}{{F}_{0}}}^{5}{D}_{0}$ excitation spectra and, from the ${}^{5}{\stackrel{\ensuremath{\rightarrow}}{{D}_{0}}}^{7}{F}_{1}$ luminescence spectra, further identified five, two, four, and two secondary centers, respectively, within these primary A--D centers. From a detailed investigation of their spectroscopic properties that specifically include the ${}^{5}{D}_{0}$ energy ${(E}_{0}),$ the ${}^{5}{D}_{0}$ lifetime $({\ensuremath{\tau}}_{0}),$ and the crystal-field strength ${(S}_{k},k=2,4,6),$ we found trends of ${E}_{0}$ in ${E}_{0}(\mathrm{A})$ $<{E}_{0}(\mathrm{B})$ $<{E}_{0}(\mathrm{C})$$<{E}_{0}(\mathrm{D}),$ ${\ensuremath{\tau}}_{0}$ in ${\ensuremath{\tau}}_{0}(\mathrm{A})$$>{\ensuremath{\tau}}_{0}(\mathrm{B})$ $>{\ensuremath{\tau}}_{0}(\mathrm{C})$$>{\ensuremath{\tau}}_{0}(\mathrm{D}),$ and ${S}_{2}$ in ${S}_{2}(\mathrm{A})$ $<{S}_{2}(\mathrm{B})$ $<{S}_{2}(\mathrm{C})$ $<{S}_{2}(\mathrm{D}).$ Local structures of the four primary ${\mathrm{Eu}}^{3+}$ centers were proposed. The A center is attributed to regular, unperturbed ${\mathrm{Eu}}^{3+}(c)$ ions and the other three B--D centers are attributed to ${\mathrm{Eu}}^{3+}(c)$ ions perturbed by the next-nearest neighbor ${\mathrm{Y}}^{3+}(a)$ ions that are created by a site exchange between ${\mathrm{Y}}^{3+}(c)$ and ${\mathrm{Al}}^{3+}(a)$ cations during crystal growing. The secondary centers' local structures were also proposed. They form due to a further perturbation of the next-nearest neighbor ${\mathrm{Eu}}^{3+}(c)$ or ${\mathrm{Al}}^{3+}(c)$ ions on each of the primary centers.