| Abstract: | Single crystals of pure and doped lead(II)chloride and lead(II)bromide were grown by gel technique employing a modified two-stage chemical reaction. Methods to minimise the predomination of needle morphology during the growth of these crystals have been investigated and the results are discussed. The grown crystals were characterised by optical transmission spectrum. Undoped and monovalent cation (K+, Na+, Cu+, Ag+ and Hg+) doped crystals of PbCl2 and PbBr2 were subjected to d.c. electrical conductivity studies. Using the log σT versus T?1 plot, the activation energies for the migration of anion vacancies in lead(II)halides are calculated. They are found to be less for the doped crystals than those of undoped ones. |
