Interpretation of the Electrocaloric Effect in Na1/2Bi1/2TiO3-SrTiO3-PbTiO3Solid Solutions

Results of direct measurements of electrocaloric effect and polarization are mutually compared in solid solutions 0.4Na1/2Bi1/2TiO3-(0.6-x)SrTiO3-xPbTiO3. Three temperature regions are distinguished in respect of a phase transition temperature. Above the phase transition, electrocaloric effect is determined by orientation of polar nanoregions by electric field. In wide temperature regions above and below the phase transition temperature, the difference between results, obtained from direct electrocaloric effect measurements and from polarization hysteresis loops, is explained by temperature dependence of concentration of polar nanoregions, oriented by electric field. Existence of a common Δ…

Phase transitions in Na0.5Bi0.5TiO3-(Sr0.7Bi0.2)TiO3-PbTiO3 solid solutions

ABSTRACTIncreasing of Sr0.7Bi0.2TiO3 concentration in Na0.5Bi0.5TiO3-Sr0.7Bi0.2TiO3 solid solutions causes increasing of Bi/Na relation and vacancies in the A-site of perovskite structure. In temperature dependence of dielectric permittivity, such a change of composition is reflected by transforming of the frequency-dependent shoulder into a maximum characteristic for relaxor ferroelectrics and diminishing of the frequency-independent maximum characteristic for Na0.5Bi0.5TiO3. Here changes in behavior of dielectric permittivity and polarization are studied if PbTiO3 is added in a certain concentration range of Na0.5Bi0.5TiO3-Sr0.7Bi0.2TiO3 solid solutions. Changes of the characteristic temp…

Direct and indirect determination of electrocaloric effect in Na0.5Bi0.5TiO3

This work has been supported by the National Research Program in the framework of the project “Multifunctional Materials and composites, photonics and nanotechnology (IMIS2).”

Phase Transitions and Electrocaloric Effect in Ca-Modified Na1/2Bi1/2TiO3–SrTiO3–PbTiO3Solid Solutions