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Öğe Characterization of 1-3 piezocomposites from PNN-PZT piezoceramics(Elsevier Science Sa, 2023) Yalcin, Ezgi; Gozuacik, Namik Kemal; Alkoy, Sedat; Sari, Huseyin Alptekin; Kaya, Mustafa Yunus; Oncel, Cinar; Mensur, EbruPiezocomposite materials combine best properties of components while minimizing their disadvantages to provide desired properties. This study reports on piezocomposites with 1-3 connectivity prepared from 0.5Pb (Ni1/3Nb2/3)O3-0.5Pb(Zr0.3Ti0.7)O3 (0.5PNN-0.5PZT) fibers and polyurethane matrix. The PNN-PZT powder was synthesized by solid-state reaction method. PNN-PZT green fibers were drawn using the alginate gelation method. Dense sintered fibers with 500-800 mu m diameter were embedded in an ordered arrangement in a polyurethane passive matrix. Structural, electrical and electroacoustic properties of PNN-PZT piezocomposite and bulk ceramic were both reported. Bulk PNN-PZT ceramics were found to have properties that are superior than the commercial soft PZT counterparts. The maximum TVR value was measured as 142.5 dB at 444 kHz for the piezocomposite, corresponding to the thickness mode resonance. The FFVS response with 3 dB variation had an average FFVS value of - 210 dB between 250 and 450 kHz band for the piezocomposite.Öğe Design, finite element analysis, fabrication and electroacoustic characterization of transducer arrays from piezoceramics with hollow cylindrical shell form(Taylor & Francis Ltd, 2022) Boz, Muhammet; Kaya, Mustafa Yunus; Ozdemir, Omer; Alkoy, SedatElectroacoustic transducers arrays operating in the 50-100 kHz frequency range are currently being investigated for underwater applications such as target detection transducers installed on underwater autonomous vehicles (UAV) and detection of underwater intruders to protect and secure economically and strategically critical coastal areas and facilities. However, the frequency range is such that it prevents the use of monolithic piezoceramics operating in the thickness mode due to the unacceptably high voltages that are required to drive them. Whereas the alternative such as Langevin-type transducer solutions have certain other assembly difficulties that arise due to the size limitations imposed on the transducer from the half-wavelength (lambda/2) arrangement requirement of the units. In our study, an entirely new alternative was proposed to overcome these difficulties. A piezoceramic transducer constructed from a hollow cylindrical shell form poled in the radial direction was designed and developed to operate at the longitudinal length extension mode. Since the hollow cylindrical piezoceramics were designed and produced with one end closed, this closed end was used as a passive cap with the transducer operating in a piston mode. ATILA finite element analysis code was used to design, analyze and fine-tune the dimensional requirements of the transducer. The center frequency of the transducer was fixed to 70 kHz. Commercial lead zirconate titanate (PZT) composition with hard piezoelectric character (PZT-4) was used as the starting powder. The slip casting method was used to obtain the cylindrical shell form. Single element transducers, as well as a hexagonal close-packed array consisting of seven units and arranged with a distance of half-wavelength (lambda/2) to obtain constructive interference at 70 kHz were constructed and tested for underwater electroacoustic performance.Öğe Design, Modeling and Fabrication of a Novel Class V Flextensional Transducer: The Sea-Shell(Ieee-Inst Electrical Electronics Engineers Inc, 2023) Kaya, Mustafa Yunus; Alkoy, SedatIn this study, a novel class V flextensional transducer (FT) was developed by assembling symmetrically convex ceramic and metal caps to form a seashell-like structure. The transducer was designed and analyzed using ATILA finite element analysis (FEA) software. The diameter, thickness, and radius of curvature of the ceramic and metal shells have been investigated as design parameters. The transducer was found to display four distinct flextensional modes in addition to the main radial resonance mode between 1 and 200 kHz frequency range. Prototypical devices were fabricated from four different commercial lead zirconate titanate (PZT) compositions and underwater performances were compared. Transmitting voltage responses (TVRs) were observed to range between 120 and 135 dB (ref 1 mu Pa/V) at frequencies above 50 kHz.Öğe Effect of texture on ultra-high strain behavior in eco-friendly NBT-0.25ST ceramics using NBT template(Wiley, 2024) Berksoy-Yavuz, Ayse; Kaya, Mustafa Yunus; Yalcin, Ezgi; Gozuacik, Namik Kemal; Mensur, Ebru<001> oriented textured (Na0.5Bi0.5Ti)O-3-0.25SrTiO(3) (NBT-0.25ST) system was fabricated using 10 mol% plate-like NBT template particles to enhance the electrical properties. Random and textured samples were prepared by a tape-casting method. Lotgering factor for textured sample was calculated as 88%. Dielectric values of the samples were comparable, and this means texturing using NBT samples of this orientation did not change the dielectric constant. The maximum unipolar strain values of random and textured NBT-0.25ST systems were found to be as similar to 0.09% and similar to 0.59%, respectively. This current study emphasizes the significant difference in maximum unipolar strain values between the random and textured versions of the NBT-0.25ST system, indicating the superiority of the textured material in terms of responsiveness to the electric field. The FOM under high electric fields of textured and random NBT-0.25ST was found to increase almost 45-fold compared with random case.Öğe 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.Öğe 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, SedatLead 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.Öğe STOKİYOMETRİK OLMAYAN NBT-ST SERAMİKLERİNİN ELEKTRİKSEL ÖZELLİKLERİNE SİNTERLEME YARDIMCISI CuO KATKISI ETKİSİNİN İNCELENMESİ(2024) Yaldız, Gülbeniz; Kaya, Mustafa YunusSon yirmi yıllık süreçte, elektromekanik cihazlarda, enerji hasadı ve enerji depolama uygulamalarında yaygın kullanıma sahip kurşun zirkonat titanat ve türevi seramiklere alternatif olarak kurşun içermeyen piezoseramiklerin araştırılması ve geliştirilmesi üzerine çok sayıda çalışma yapılmıştır. Bu araştırmalar içerisinde sodyum bizmut titanat (Na0.5Bi0.5TiO3-NBT) esaslı seramikler ve morfotropik faz sınırı (MFS) kompozisyonları sergiledikleri elektriksel özellikler ile öne çıkmaktadır. Bu çalışmada, NBT seramik bileşimi stronsiyum titanat (SrTiO3-ST) ile modifiye edilmiştir. [Na0,5Bi0,5TiO3]0,75[Sr1-xTiO3-x]0,25-NBT-SnT (x=0,25) kimyasal formülünce stokiyometrik olmayan seramik kompozisyonu katı hal kalsinasyon yöntemiyle sentezlenmiş ve CuO katkısının sinterleme performansı ve özellikleri üzerine etkisi incelenmiştir. Sentezleme işlemi sonrasında psedokübik simetride NBT-SnT fazının yüksek oranda oluştuğu görülmüştür. Sinterleme yardımcısı CuO katkısı miktarına bağlı olarak sinterleme işleminde ikincil faz oluşumu gözlenmiştir. En yüksek yoğunlaşma oranı %0,5 CuO katkılı seramiklerde 1200 °C’de 3 saat sinterleme ile elde edilmiştir. Bu seramikler için 10 kHz frekansında dielektrik sabiti (K) 570 ila 1300 arasında, dielektrik kayıp (tan ?) değerleri 0,04 ila 0,11 arasında, relaksör ferroelektrik davranışa işaret eden yayınımsallık derecesi (?) ise 1, 84 ila 1,99 arasında değişmektedir.
