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    Fabrication of 0.94NBT–0.06BT textured ceramics using plate-like NBT templates and their electrical properties
    (Springer, 2022) Berksoy-Yavuz A.; Kaya, Mustafa Yunus; Avcı T.; Cakırbas G.; Menşur E.
    The effect of crystallographic texture on the properties of 0.94(Na0.5Bi0.5TiO3)–0.06BaTiO3 (0.94NBT–0.06BT) ceramics were investigated in this study. The optimized rectangular plate-like Na0.5Bi0.5TiO3 (NBT) templates synthesized by a three-step molten salt method were used for the texturing. Dimensions of the major surfaces of the templates which were parallel to the (001) planes were measured as 8.4 µm × 10 µm (length × width) and 1 µm thickness on the average. The green textured ceramics were fabricated by tape casting method and then sintered. All ceramics were crystallized in pure perovskite structure and the degree of grain orientation was calculated as f = 91%. Brick wall-like microstructure for the textured NBT–BT ceramics with average grain size of ~ 12 µm was obtained by scanning electron microscopy. Depolarization temperature (Td) and temperature of maximum (Tm) of the dielectric permittivity were determined as 119 °C and 341 °C at 10 kHz for the textured ceramic, respectively. The value of maximum dielectric permittivity of textured ceramics was measured as εrmax ~ 5409 at 10 kHz. The high field (@50 kV/cm) piezoelectric d33* value was increased from 239 to 412 pm/V by texturing of the 0.94NBT–0.06BT ceramics. NBT template addition and texture development led to a decrease in AC conductivity.
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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.