Materials Science and Engineering / Malzeme Bilimi ve Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/4719
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Article Citation - WoS: 11Citation - Scopus: 11Enhanced Electrocaloric Effect of P(vdf-Trfe) Nanocomposites With Ca and Sn Co-Doped Batio3 Particles(Elsevier, 2023) Adem, Umut; Demir, Mustafa Muammer; Adem, Umut; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyWe report on the enhancemenent of electrocaloric effect in solution cast polymer nanocomposites based on Poly (vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE) 55-45] with Ca and Sn co-substituted BaTiO3 ceramic fillers (Ba0.94Ca0.06Ti0.925Sn0.075O3, BCST). Saturated hysteresis loops and normal ferroelectric behaviour of the copolymer-based nanocomposites-as opposed to the relaxor ferroelectric nature of the terpolymer-based ones-allow the utilization of the indirect method to estimate the electrocaloric properties. Both the dielectric constant and electrocaloric temperature change (AT) increases as the particle content increases. Maximum adiabatic temperature change was obtained as 6.96 K under 900 kV/cm for the 10 vol % BCST containing polymer composite around the Curie temperature of the copolymer (70 degrees C). This relatively large electrocaloric strength is slightly lower than those obtained for terpolymer-based nanocomposites.Article Citation - WoS: 6Citation - Scopus: 6First-Principles Study of Dissociation Processes for the Synthesis of Fe and Co Oxide Nanoparticles(American Chemical Society, 2018) Özdamar, Burak; Bouzid, Assil; Ori, Guido; Massobrio, Carlo; Boero, Mauro; 01. Izmir Institute of TechnologyThermal decomposition is a practical and reliable tool to synthesize nanoparticles with monodisperse size distribution and reproducible accuracy. The nature of the precursor molecules and their interaction with the environment during the synthesis process have a direct impact on the resulting nanoparticles. Our study focuses on widely used transition-metal (Co, Fe) stearates precursors and their thermal decomposition reaction pathway. We show how the nature of the metal and the presence or absence of water molecules, directly related to the humidity conditions during the synthesis process, affect the decomposition mechanism and the resulting transition-metal oxide building blocks. This, in turn, has a direct effect on the physical and chemical properties of the produced nanoparticles and deeply influences their composition and morphology.Article Citation - WoS: 64Citation - Scopus: 67Hierarchically Structured Metal Oxide/Silica Nanofibers by Colloid Electrospinning(American Chemical Society, 2012) Horzum Polat, Nesrin; Demir, Mustafa Muammer; Mun˜oz-Espí, Rafael; Glasser, Gunnar; Demir, Mustafa Muammer; Landfester, Katharina; Crespy, Daniel; 03.09. Department of Materials Science and Engineering; 03. Faculty of Engineering; 01. Izmir Institute of TechnologyWe present herein a new concept for the preparation of nanofibrous metal oxides based on the simultaneous electrospinning of metal oxide precursors and silica nanoparticles. Precursor fibers are prepared by electrospinning silica nanoparticles (20 nm in diameter) dispersed in an aqueous solution of poly(acrylic acid) and metal salts. Upon calcination in air, the poly(acrylic acid) matrix is removed, the silica nanoparticles are cemented, and nanocrystalline metal oxide particles of 4-14 nm are nucleated at the surface of the silica nanoparticles. The obtained continuous silica fibers act as a structural framework for metal oxide nanoparticles and show improved mechanical integrity compared to the neat metal oxide fibers. The hierarchically nanostructured materials are promising for catalysis applications, as demonstrated by the successful degradation of a model dye in the presence of the fibers.