High-pressure luminescence spectroscopy of EuAl2O4 phosphor

EuAl2O4 powder phosphor was prepared by solid-state reaction of EuO and Al2O3 oxides in vacuum. The influence of conditions of preparation on spectral lineshape of Eu2+Eu2+ emission was analyzed. It was found that the fluorescence spectra of vacuum-prepared EuAl2O4 samples at 300 K present the superposition of three bands peaked at 430, 500 and 528 nm, corresponding to the 4f65d1→4f7(S7/28) transition of Eu2+Eu2+ ions in the different sites of EuAl2O4 lattice. The luminescence of Eu2+Eu2+ centers in EuAl2O4 host was also studied using the high-pressure spectroscopy up to 67 kbar. It was found that the bright green-yellow fluorescence of EuAl2O4 at 300 K in the band peaked at 520–530nm range can be presented by superposition of two Gaussian sub-bands. The different pressure shifts −23 and -27cm-1/kbar for two sub-bands were found. Such a structure of the emission spectrum was attributed to the existence of two different Eu2+Eu2+ centers in the EuII2+ sites of EuAl2O4 lattice with higher coordination number.