Electron spin resonance (ESR), thermally stimulated luminescence (TSL) and electrical conductivity measurements were performed on Mo- and (Mo,La)-doped ${\mathrm{PbWO}}_4$ crystals in order to understand electron capture processes involving the Mo-based defects. A defect consisting of an electron localized around the ${\left({\mathrm{MoO}}_4\right)}^{2-}$ complex (${\left({\mathrm{MoO}}_4\right)}^{3-}$ center) was evidenced by ESR after UV illumination and studied in detail; the thermally activated detrapping of electrons from ${\left({\mathrm{MoO}}_4\right)}^{3-}$ centers in the 200–250 K temperature region was described also by TSL measurements. Finally, in La-codoped samples, free electrons in the conduction band were found by both ESR and electrical conductivity experiments, unveiling a donor character of ${\mathrm{La}}^{3+}$ impurity in the PWO lattice. Microscopical aspects of the energy storage processes and radiation resistance of the material are discussed.

• Received 6 August 2004

DOI:https://doi.org/10.1103/PhysRevB.71.235108