Wet-chemical preparation of Ce3+-activated K2LaX5 (X = Cl, Br or I) phosphors

Abstract

There has been a renewed interest in Ce(3+) -activated halide phosphors due to applications as scintillation detectors, especially for positron emission tomography. For K(2) LaCl(5), the light yield increases and the energy resolution (FWHM) improves with increasing Ce(3+) doping. K(2) LaX(5) compounds are also important as laser hosts for the mid-IR range. K(2) LaCl(5):Nd crystals show bright mid-IR luminescence, which makes them a candidate for IR laser materials. Efficient emission in the IR range has also been reported in K(2) LaCl(5):U(3+). A one-step, wet chemical process for preparing Ce(3+)-activated K(2) LaCl(5) phosphor is described. Intense luminescence of Ce(3+) can be observed in the as-prepared powders without any heat treatment. The availability of such powders opens up several exciting possibilities, such as growing single crystals without going to the high temperatures required for melting the constituent chlorides, or even obtaining processed, transparent, Ce(3+)-activated materials without taking recourse to crystal growth.