X-ray excited optical luminescence and morphological studies of Eu-doped LiAl5O8

Abstract

Abstract This work aims the investigation of lithium excess influence on the X-ray Excited Optical Luminescence (XEOL) and X-ray Absorption Spectroscopy (XAS) of Eu-doped LiAl5O8 samples. XEOL spectra excited at Eu LIII-edge is composed of emission peaks attributed to the emission of Eu2+, Eu3+ and Cr3+ ions. The results showed that lithium excess contributes to important differences concerning the relative intensity of Eu2+ and Eu3+ emissions, suggesting that can Li+ or Li vacancies act to create defects able to stabilize the Eu2+ on the host lattice. Scanning electronic microscopy images showed that the Li+ excess did not contribute to significant changes on the particles morphology and size. Based on the XAS measurements, we suggest that defects such as V’Li may be created in the LiAl5O8 structure contributing to the Eu2+ stabilization. Consequently, the Li+ excess favors the Eu3+ stabilization and the preparation of red emitting phosphors.