Outlining origin of diffuse plus relaxor ferro- to para-electric phase transition in lead metaniobate-based materials

Lead metaniobate-based ferroelectrics were studied in terms of thermal spectra of dielectric permittivity, Curie-Weiss law and hysteresis loop characteristics. This work shows that while dopants are able to promote a change of the ferro- to para-electric phase transition appearance from normal to diffuse, transformation to a diffuse plus relaxor transition behavior is linked to incommensurate superstructures present and dielectrically-active, with an intrinsically frequency-dispersive response, in these materials toward low temperatures. This statement is also supported by observation of hysteresis loops showing a transformation trend to pseudo-slim-like, even in the normal ferroelectrics, when moving into the temperature region of incommensuration manifestation.