Alternating current-field effects on the freezing temperature of La-modified lead magnesium niobate-lead titanate crystalline solutions for compositions near to the morphotropic phase boundary have been studied by dielectric spectroscopy. Charge imbalance due to La substitution (0-10 at.%) in [Pb(Mg1/3Nb2/3)O3]0.65(PbTiO 3)0.35 was compensated by changing the B-site cation ratio. The frequency dispersion in the dielectric constant was found to increase with increasing La substitution. Relaxor-like dielectric characteristics were induced for La concentrations greater than 5 at.%. It was also found that the dielectric constant maximum (εmax′) increased and the temperature of εmax′ decreased with increasing ac field. In addition, a threshold electric field was observed above which nonlinearities became evident in the dielectric response and the freezing temperature was reduced.
ASJC Scopus subject areas
- Physics and Astronomy(all)