Luminescence and site occupancy of Ce3+ in Ba2Ca(BO3)2

The phosphors of Ce3+ activated Ba2Ca(BO3)(2) with chemical formulas Ba2(1-x)CexNaxCa(BO3)(2) and Ba2Ca1-2xCexNax(BO3)(2) were prepared. The luminescence properties have been investigated under vacuum ultraviolet UV and x-ray excitation. Though the point defects Ce-Ba(center dot) and Na-Ba(') are expected to occur in samples Ba2(1-x)CexNaxCa(BO3)(2), and Ce-Ca(center dot) and Na-Ca(') are expected to appear in samples Ba2Ca1-2xCexNax(BO3)(2) according to the formulas of the compounds, however, two types of Ce3+ centers were found in all samples due to the occupancy of both Ba2+ and Ca2+ sites. So the influence of doping concentration on the preferential site occupancy was studied, and it was found that Ce3+ ions always preferentially enter Ba2+ sites at low doping concentration for both samples Ba2(1-x)CexNaxCa(BO3)(2) and Ba2Ca1-2xCexNax(BO3)(2). In addition, the 5d energy levels and decay behaviors for Ce3+ in Ba2+ and Ca2+ sites, the concentration quenching, and the x-ray excited photon output were evaluated to clearly reveal the luminescence features.