Crystal structure, photoluminescence and cathodoluminescence of Ba1-xSrxAl2O4 doped with Eu2+

Abstract

Herein we describe the synthesis, crystal structures, photoluminescence (PL) and cathodoluminescence (CL) spectra of phosphors in the Sr0.97-xBaxEu0.03Al2O4 system between x = 0 and x = 0.97. The syntheses of these phosphors were carried out by solid state reactions at 1350°C in mixed gas (H2/N2). The molar fractions of the alkaline earth elements were varied in steps of 0.1. The Sr1-xBaxAl2O4 series manifested solid solutions of a monoclinic phase (at the Sr-rich side) and a hexagonal phase (at the Ba-rich side). At the Ba-rich side of Srx-1BaxAl2O4:Eu2+ we found evidence in the PL spectra that the hexagonal phase differed as the xBa fraction changed: it changed at room temperature from the ferroelectric P63 structure at xBa=1 to the paraelectric P6322 phase at xBa≈0.9 and at xBa≈0.8 it went back to P63. Unlike the PL spectra, the CL spectra of the hexagonal phase of Sr0.97-xBaxEu0.03Al2O4 at x ≥ 0.5 indicated only the paraelectric P6322 phase at room temperature.