The effects of Nd impurity on the optical, dielectric and electrical properties of PbWO4 single crystals

A series of Nd-doped PbWO4 (PWO) crystals are gown using the Czochralski method and their optical and electrical properties are investigated. It is found that the Nd3+ ion characterizes the optical absorption spectra of Nd-containing crystals. On increasing the concentration of Nd, the optical absorption edge of the crystals shifts to low energy, which results from the defect energy level effect. Similar to other trivalent rare-earth ions, the improvement of radiation hardness is also achieved in Nd-doped PWO. Impedance spectroscopy reveals two dielectric loss peaks, which are assigned to [2(Nd-Pb(3+))(center dot)-(V-Pb)(")] and [(Nd-W(3+))("')-(Nd-Pb(3+))(center dot)-(V-o)(center dot center dot)] defect complexes, respectively. High electrical conductivity with an activation energy of about 0.29 0.02 eV at high temperature is present in PWO containing 1.6% Nd. It is of interest that the heavily Nd-doped PWO could be a high-temperature ionic conductor. (c) 2005 WILEYNCH Verlag GmbH & Co. KGaA, Weinheim.