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Öğe Design, development and characterization of a mid-frequency (35 khz) tonpilz transducer array from 0.675PMN-0.325PT piezoceramics(Chulalognkorn University, 2022) Çiftçi, Merve Nur; Değirmenci, Berk; Böbrek, İrem; Alkoy, Sedat; Aykaç, Aykut; Boz, Muhammet; Berksoy Yavuz, Ayşe; Yalçın, EzgiA mid-frequency tonpilz transducer array was designed and analyzed by finite element method using commercial ATILA code and constructed using piezoceramic rings with lead magnesium niobate (PMN)-lead titanate (PT) composition. The morphotropic phase boundary (MPB)0.675Pb(Mg1/3Nb2/3)O-3-0.325PbTiO(3) composition was chosen to obtain higher performance from the transducer due to the superior dielectric and electromechanical properties of the MPB compositions. A pure perovskite phase was obtained from the ceramics. Piezoelectric charge coefficient (d(33)) was measured as 435 pC.N-1. Single tonpilz element and an array consisting of 7-unit array were constructed and later potted in polyurethane for underwater measurements. A second array was also constructed for comparison from commercial hard Pb(Zr,Ti)O-3-PZT ceramics. The longitudinal piston mode vibration frequency of the tonpilz transducer was measured around 33 kHz in air and around 35 kHz in water. The PMN-PT based array was found to have a comparable transmit perfonnance and a superior receive performance compared to PZT.Öğe Electrical properties, EPR analyses and defect chemistry of Mn-doped 0.675PMN-0.325PT piezoceramics(Elsevier Science Ltd, 2020) Berksoy Yavuz, Ayşe; Mensur Alkoy, Ebru; Erdem, Emre; Alkoy, SedatThe morphotropic phase boundary solid solution of 0.675Pb(Mg1/3Nb2/3)O-3 -0.325PbTiO(3) (0.675PMN-0.325PT) were studied. Manganese (Mn) was used as a dopant element in 0.4 mol% and 0.7 mol% ratios because of its multiple oxidation states. Sintering was done either in the air or under an oxygen-rich atmosphere. Both the effect of doping and sintering atmosphere on the electrical properties were reported. The ceramic with 0.4 mol% were exhibited higher properties such as piezoelectric charge coefficient (d(33)), dielectric constant, polarization values compared to undoped and 0.7 mol% Mn-doped ceramics. Electron paramagnetic resonance (EPR) spectroscopy was used to resolve the oxidation state of Mn in the 0.675PMN-0.325PT structure. The electrical properties were discussed and explained using defect chemistry.Öğe Structural and electrical properties of ⟨001⟩ textured 0.26PIN-0.40PMN-0.34PT ternary system(Springer, 2019) Berksoy Yavuz, Ayşe; Mensur Alkoy, Ebru; Gözütok, Ebru; Dursun, Sinan; Yılmaz, Hüseyin; Alkoy, SedatLead indium niobate (PIN)-lead magnesium niobate (PMN)-lead titanate (PT) solid solution in the ratio of 0.26PIN-0.40PMN-0.34PT was fabricated by tape-casting in random and < 001 > (pc) textured forms. PIN-PMN-PT was textured using 5 vol% barium titanate templates. The Lotgering factor, f, of 0.26PIN-0.40PMN-0.34PT textured ceramics was approximately calculated as 95%. Quenching from above the Curie temperature down to the room temperature was applied to both random and textured samples, which led to drastic increases in the ferroelectric and piezoelectric properties. The Curie temperature, dielectric constant (epsilon(r)), converse piezoelectric charge coefficient (d33*) and piezoelectric voltage constant (g(33)) of textured and quenched sample were found to be 223 degrees C, 2455, 1432 pm/V and 27.60 x 10(-3) Vm/N, respectively.Öğe Structural features and energy harvester device applications of textured 0.675 PMN-0.325 PT piezoceramics(Springer, 2020) Berksoy Yavuz, Ayşe; Savacı, Umut; Turan, Servet; Alkoy, Sedat; Mensur Alkoy, EbruIn the current study, textured lead magnesium niobate-lead titanate solid solution with composition 0.675Pb(Mg1/3Nb2/3)O-3-0.325PbTiO(3) (0.675PMN-0.325PT) has been fabricated with 0.7 mol% manganese (Mn) doping to enhance the soft character and the figure of merit (FOM). Random and textured PMN-PT plates were prepared by tape casting where 1 vol% plate-like barium titanate (BaTiO3) single-crystal templates were added to induce texture. A detailed structural investigation using scanning/transmission electron microscopy (STEM) and precession electron diffraction techniques has been conducted to establish the orientational relationship between the PMN-PT matrix and the BT templates. The FOM of textured and doped PMN-PT was found to increase for almost fourfold compared to random undoped case. Characterization of the energy harvesting (EH) performance of unimorph EH devices indicated an over twofold increase in the output power of the doped and textured case in comparison to the undoped and random PMN-PT ceramics.Öğe Temperature dependent electrical and electrocaloric properties of textured 0.72PMN-0.28PT ceramics*(Taylor & Francis Ltd, 2022) Böbrek, İrem; Berksoy Yavuz, Ayşe; Kaya, Mustafa Yunus; Alkoy, Sedat; Okatan, Mahmut Barış; Mısırlıoğlu, İbrahim Burç; Mensur Alkoy, EbruLead 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 (d(33)*) 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 (Delta T-EC) of similar to 0.5 K was calculated from the PMN-28PT ceramics at around 80 degrees C under an electric field of 60 kV/cm. Development of texture was demonstrated to have led to an anisotropy in the EC response.
