Ultralow dielectric losses in pyrochlore films of the PbO–MgO–Nb2O5–TiO2 system.

(1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 (PMNT) (with x=0.1) thin films were prepared on Pt-coated silicon substrates by radio-frequency magnetron sputtering and postdeposition annealing method. A well-crystallized pyrochlore phase structure, which started to nucleate and grow at 450–500 °C, was formed in the PMNT thin films. These pyrochlore-structured PMNT thin films show ultralow dielectric losses with a typical loss tangent as low as 0.001, accompanied by a relatively high dielectric constant ([variant_greek_epsilon]r=176). Such an extremely low dielectric loss, having never been obtained in thin films of perovskite PMNT, is probably ascribed to the specific structural feature of pyrochlore phase, chemically different from its perovskite counterpart, and ascribed to the avoidance of the polar domain-related losses. [ABSTRACT FROM AUTHOR]