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    Lead-based antiferroelectrics revisited for high energy density capacitors and large strain actuators
    (Taylor and Francis Ltd., 2021) Sarı, Hüseyin Alptekin; Gözüaçık, Namık Kemal; Kaya, Mustafa Yunus; Menşur, Ebru; Alkoy, Sedat
    Lead zirconate stannate titanate (PZST) ceramics with the generic composition of Pb1-0.5xNbx[(ZrySn1-y)1-zTiz]1-xO3 with x representing Nb content (x = 0 or 0.02), y representing Zr:Sn ratio (y = 0.57 or 0.60), and z representing Ti content (z = 0.06 or 0.08), and lead lanthanum zirconate titanate (PLZT) ceramics with the general composition of Pb1-xLax(ZryTi1−y)1−x/4O3 with x = 0.050 − 0.120 were synthesized using solid state reaction method and sintering. The energy density and field induced strain behavior of these compositions were investigated for capacitor and actuator applications, respectively. The focus of the study was to evaluate and discuss the change in the polar state of these ceramics from normal ferroelectric to antiferroelectric to relaxor antiferroelectric to linear dielectric with compositional modification. The highest releasable energy density (1.053 J/cm3) was obtained from the antiferroelectric Pb[(Zr0.60Sn0.40)0.94Ti0.06]O3 composition among the PZST compositions that were investigated, but the efficiencies were generally low (max. 60%) due to the large hysteresis that was observed in these compositions. The highest field induced strain level of 0.26% was also measured in the same composition. In the case of PLZT compositions, the highest releasable energy density values (0.313 J/cm3) with much higher efficiencies (76%) and highest field induced strain levels (0.23%) were obtained from the PLZT compositions with relaxor antiferroelectric character.
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    Temperature Dependent Electrical and Electrocaloric Properties of Textured 0.72PMN - 0.28PT Ceramics*
    (Taylor and Francis Ltd., 2021) Bobrek, Irem; Berksoy-Yavuz, Ayse; Kaya, M. Yunus; Alkoy, Sedat; Okatan, M. Baris
    Lead magnesium niobate (PMN) - lead titanate (PT) solid solution ceramics in the ratio of 0.72PMN-0.28PT was produced by a combination of tape-casting in ⟨001⟩pc textured and random forms. The Lotgering factor, f, of textured ceramics was approximately calculated as 80%. Modified Curie-Weiss analysis indicated relaxor dominant behavior for both the random and textured ceramics. Development of texture led to an enhancement in the electromechanical properties with converse piezoelectric charge coefficient (d33*) under 20 kV/cm electric field reaching 545 pm/V for the textured ceramic. Electrocaloric (EC) behavior of random and textured ceramics were obtained from indirect measurements using temperature dependent polarization vs. electric field hysteresis loops. An EC temperature change (ΔTEC) of ∼0.5 K was calculated from the PMN-28PT ceramics at around 80 °C under an electric field of 60 kV/cm. Development of texture was demonstrated to have led to an anisotropy in the EC response.