Cluster polarization of Cd2Nb2O7 compound

The direct-current (dc) electric-field dependence of dielectric constant ar ound paraelectric-ferroelectric transition in Cd2Nb2O7 has been studied. Th e results show significant suppression of the dielectric constant by the ap plication of de bias. The electric-field dependence of the dielectric const ant at the temperature around paraelectric-ferroelectric phase transition c an be well described by the modified Devenshire relation including a cluste r term, i.e., epsilon(E) = epsilon(1) - epsilon(2)E(2) + epsilon(3)F(4) + ( Px/epsilon(0))[cosh(Ex)](-2). The fit parameters indicate that the polar-cl uster carries polarization P = similar to 0.5- 2.5 mC/m(2) with the cluster size of L= similar to 11 - 15 nm. (C) 2000 American Institute of Physics. [S0003-6951(00)04531-9].