The effects of La3+ doping on luminescence properties of PbWO 4 single crystal

X-ray-excited luminescence (XEL), thermoluminescence (TL), photoluminescence under excitation of UV light and X-ray photoelectron spectroscopy (XPS) measurements were conducted on PbWO 4 (PWO) single crystals doped with La3+ at a series of concentration levels. With the increase of doping levels, the intensity of PWO in the XEL or the excitation-emission spectra was found to decrease accordingly, especially in the case of heavy doping. TL peaks in the range from room temperature to 200 deg. C disappeared after the doping with La3+. A splitting of the La3d XPS peak in the heavy La3+-doped samples was observed and proposed to be responsible for that. At a high doping level, La3+ would occupy W-sites besides Pb-sites and thus induce a self-compensation via pairs [(La W3+)'''-(LaPb3+)*]-(VO)* or clusters [3(LaPb3+)*-(LaW3+)'''], where nonradiative recombination was previously reported to occur. The mechanism of the influence on luminescence was also discussed in this paper