Polarization relaxation in thin-film relaxors compared to that in ferroelectrics

Abstract

were prepared, and their dielectric properties were studied in a broad range of the measurement conditions. In the ferroelectric state, the presence and the change of configuration of the domains determined both the dynamic dielectric nonlinearity and the polarization hysteresis. In thin-film relaxors, the orientation of the randomly interacting dipoles in a random field was responsible for the dynamic dielectric nonlinearity, while the observed hysteresis was suggested to arise due to connection between the applied field and the relaxation times of both the dipoles and the internal field. In thin-film (Ba,Sr)TiO 3 , the hightemperature dielectric hysteresis was found to be relaxorlike.

Ferroelectricity in Strain-FreeSrTiO3Thin Films

“…These findings indicate that the most likely reason for the ferroelectricity is a small amount of Sr deficiency in our nominally stoichiometric STO films. A clear distinction between STO and previously reported relaxor systems by A-site cation doping [28][29][30][31] is that STO has only Sr on the A site with minute amounts of unintentional Sr deficiency.…”

Evidence for Strain-Induced Ferroelectric Order in Epitaxial Thin-FilmKTaO3

“…In thin films, the difference is well seen in the dependence of the response on amplitude E ac of ac electric field, C=S (E ac ) [22]. This can be used to reveal the presence of FE domains.…”

Diffuse phase transitions in epitaxial(Ba,Sr)TiO3superlattices

“…The dispersion can hardly be ascribed to a Maxwell-Wagner relaxation shown to result in a considerably larger variation of Ј and tan ␦ with f. 21 The peaks in Fig. 3 resemble those typically observed in thin-film heterostructures of perovskite relaxors 16 and also BST films. 22 The maximum permittivity m Ј ͑i.e., that measured at temperature T m ͒ varies with frequency ͓Fig.…”

“…The time 0 can qualitatively be related to the height of barriers between different dipole orientations. 24 By analogy with thin-film relaxors, 16 the decrease of T f and the increase of f 0 ͑decrease of 0 ͒ indicate changes in relaxation time spectra.…”

“…It should be noted that the antiferroelectric coupling 15 previously concluded from the observation of a double-peak dependence of permittivity on electric field seems to be questionable since similar double-peak dependences are typical for thin-film relaxors. 16 Despite the large amount of publications on phenomenological and first-principles modeling of strain effects in per-ovskite FE thin films and superlattices, engineering of the superlattice with enhanced dielectric permittivity remains rather empirical. Most of the experimental studies are focused on growth, microstructural analysis, and roomtemperature characterization of polarization or dielectric permittivity, especially with much work done for BaTiO 3 : SrTiO 3 superlattices.…”