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    Eco-Friendly Green Synthesis of Zinc Oxide Nano/Microparticles Using Aqueous Leaf Extract of Polygonum cognatum Meisn. Plant
    (Sakarya University, 2024) Akça, Erdem
    The environmentally friendly plant-based green synthesis approach provides a fabulous opportunity to produce versatile zinc oxide powders with multifarious morphology and/or size. In this study, it was mainly aimed at using Polygonum cognatum Meisn. extract to synthesize zinc oxide powder via a simple green synthesis route. For this purpose, zinc nitrate solution was mixed with an aqueous extract of fresh Polygonum cognatum Meisn. plant leaves to obtain a zinc-based precursor, and then zinc oxide powder was synthesized by means of calcination conducted at 400°C for 2 hours in air. Phase, spectroscopic, and microstructural analysis techniques, as well as Rietveld refinement method and Williamson-Hall analysis, were performed to investigate the powder characteristics. It was found that the synthesized high-purity zinc oxide powder had a hexagonal wurtzite crystal structure. Zinc oxide powder was observed to have a particularly large amount of nano-sized equiaxed particles (~25 nm in average diameter) together with micron-sized hourglass-like particles consisting of two hexagonal prisms (each <1 μm in height). All in all, the main implication of our research is that the Polygonum cognatum Meisn. plant can be potentially used as a biomass source for the green synthesis of zinc oxide nano/microparticles. © 2024, Sakarya University. All rights reserved.
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    Templated grain growth of Bi(Zn0.5Zr0.5)O3 modified BiScO3?PbTiO3 piezoelectric ceramics for high temperature applications
    (Taylor & Francis, 2021) Akça, Erdem; Duran, Cihangir; Kowalski, Ben; Sehirlioglu, Alp
    2.5Bi(Zn0.5Zr0.5)O3−37.5BiScO3−60PbTiO3 (BZZ-BS-PT) ceramics were successfully textured in the [001] by templated grain growth (TGG) process using 5 vol% <001>-oriented BaTiO3 (BT) plate-like templates. The templates were aligned in the matrix powder via tape casting and textured BZZ-BS-PT ceramics sintered at 1100°C for 3 h in air had a relative density of 98% and a Lotgering factor of 0.91. Chemically stable BT templates in Pb and Bi-rich BZZ-BS-PT system gave rise to the formation of highly oriented polycrystalline structure with larger block-like grains. A very high unipolar strain of 0.3% and low-field (<5 kV/cm) piezoelectric charge coefficient (d33) of 930 pm/V when driven at 50 kV/cm were achieved in highly textured ceramics together with a Curie temperature (TC) of 403°C. The TGG approach significantly improved piezoelectric properties of the BZ-BS-PT ceramic system without deteriorating the dielectric properties, which is a very promising high-performance candidate for high-temperature sensor, transducer and actuator applications.