Preparation and X-ray luminescence of Ba$_{4\pm x}$Ce$_{3\pm x}$F$_{17\pm x}$ solid solutions

Single-phase BaF$_2$ : Ce solid solutions containing 30 – 40 mol. % cerium with the simultaneous entry of potassium into the crystal lattice in an amount of 0.7 – 0.8 mol. % were prepared by coprecipitation from aqueous nitrate solutions with potassium fluoride as the fluoridating agent. The cerium X-ray luminescence intensity increases in response to increasing cerium concentration contrary to the concentration quenching effect.