Nanoscale clusters and phonon anomalies in relaxor-ferroelectric

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Relaxor ferroelectrics are key multi-functional materials because of their high dielectric permittivity, piezoelectric and optoelectic coefficients, which are basis of a number of technological applications including RAMs. They exhibit diffuse phase transitions over a broad temperature range, frequency dependence of the dielectric-permittivity maximum and subtle structural anisotropy to long-coherence probe radiation. The interplay between local chemical variations, polar-cluster formation and dynamics, and the unique relaxor properties is still far from being well understood. Polarised Raman spectroscopy, synchrotron X-ray diffraction as well as piezoresponse force microscopy (PFM) will be applied to doped lead-based perovskite-type single-crystal relaxors, in order to analyse the chemically-induced changes in the ferroic clusters. Our research will focus mainly on La-doped PbSc0.5B”0.5O3 (B” = Ta, Nb) as well as on PbZn1/3Nb2/3O3-PbTiO3. PFM analyses will be conducted also on Ba- and Ru- doped relaxor-ferroelectrics investigated during the previous project MI 1127/1-1. The results achieved within this project will give further insights into the atomic clustering responsible for the relaxor properties and will be of high significance for the design of innovative technologically important materials.