Yazar "Akbas, Hatice Zehra" seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe Accelerated formation of BaTiO3 ceramics with mechanochemical processing in different liquids(Elsevier Science Sa, 2017) Akbas, Hatice Zehra; Aydin, Zeki; Guder, Ferhat; Turgut, SelvinBaTiO3 powders were synthesized from BaCO3 and TiO2 with mechanochemical processing using a shaker by solid-state reactions in distilled water, methanol, and acetone. Decomposition of BaCO3, disproportionation of the liquids and hydrous titanium oxide are led to formation of the BaTiO3 ceramics. The liquids are accelerated the formation of BaTiO3 dependent on the O-H bands of the liquids structure. More O-H bands increased the density of the calcined powders, and improved the microstructure of sintered BaTiO3 ceramics. The density of the calcined powders is 4.67, 3.66, and 3.49 g/cm(3) for the water, methanol, and acetone respectively. X-ray Diffraction (XRD) and Raman spectroscopy analysis were verified the structure of BaTiO3. The differences of the microstructure are clearly shown that the micrographs of sintered pellets by Scanning Electron Microscopy (SEM). Depending on the liquid, the process led directly to normal and abnormal grain growth of the sintered samples. (C) 2016 Elsevier B.V. All rights reserved.Öğe Dielectric spectroscopy analysis of BaTiO3 with mechanochemical process in different liquids(Elsevier Science Bv, 2017) Akbas, Hatice ZehraDistilled water, methanol, and acetone, have been used to investigate the effects of the homogenization medium on the impedance properties of BaTiO3 ceramics produced by the solid state reaction method. The complex permittivity, complex impedance, resistivity, and complex electric modulus of the ceramics were studied by the dielectric spectrometer in a wide frequency range of 100 mu Hz to 20 MHz at room temperature. The complex impedance and complex electric modulus showed that the materials have a relaxation time with a different mean time constant called the Maxwell-Wagner-Sillars (MWS) type relaxation. The minimum dielectric loss found the ceramic reagents homogenized in distilled water, which is crucial for many electronic applications. The complex permittivity and resistivity measurements showed that using water instead of acetone and methanol has a positive effect on the small loss of electrical properties of barium titanate ceramics.Öğe Effects of ultrasonication and conventional mechanical homogenization processes on the structures and dielectric properties of BaTiO3 ceramics(Elsevier Science Bv, 2017) Akbas, Hatice Zehra; Aydin, Zeki; Yilmaz, Onur; Turgut, SelvinThe effects of the homogenization process on the structures and dielectric properties of pure and Nb-doped BaTiO3 ceramics have been investigated using an ultrasonic homogenization and conventional mechanical methods. The reagents were homogenized using an ultrasonic processor with high-intensity ultrasonic waves and using a compact mixer-shaker. The components and crystal types of the powders were determined by Fourier-transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses. The complex permittivity (epsilon', epsilon'') and AC conductivity (sigma') of the samples were analyzed in a wide frequency range of 20 Hz to 2 MHz at room temperature. The structures and dielectric properties of pure and Nb-doped BaTiO3 ceramics strongly depend on the homogenization process in a solid-state reaction method. Using an ultrasonic processor with high-intensity ultrasonic waves based on acoustic cavitation phenomena can make a significant improvement in producing high-purity BaTiO3 ceramics without carbonate impurities with a small dielectric loss. (C) 2016 Elsevier B.V. All rights reserved.Öğe Structural Differences of BaTiO3 Ceramics Modified by Ultrasonic and Mechanochemical Methods(Springer, 2018) Aydin, Zeki; Turgut, Selvin; Akbas, Hatice ZehraBarium titanate powders were synthesized by the modified solid-state method with ultrasonic (5 min) and mechanochemical (12 h) deagglomeration methods. The structure of the samples was verified using Fourier transform infrared spectroscopy (FT-IR) and X-ray diffractometer (XRD). Scanning electron microscopy (SEM) analysis of the powders showed that using ultrasonic deagglomeration significantly decreased the particle size with perfect homogeneity in the shortest time. The particle size of the powders was calculated as 44.7 nm and 80.4 nm for ultrasonic and mechanochemical deagglomeration, respectively. The sintered pellet by ultrasonic method had no abnormal grain growth, and the grain sizes were between 10 and 30 m. The pellet by mechanochemical method had an abnormal grain growth, and the grain sizes were between 10 and 100 m. The results showed that ultrasonication remarkably improved the structure of the samples in the shortest time.Öğe Ultrasonication effect based on the coordination number on the structure of Ba0.44Sr0.56Ti(1-x)InxO3 ceramics(Elsevier Science Sa, 2017) Akbas, Hatice ZehraLead-free Ba0.44Sr0.56Ti(1-x)InxO3 (x % = 0, 4, 8, 10) ceramics synthesized by the solid state reaction are modified by ultrasonication. The X-ray diffraction analysis confirmed that the Ba0.44Sr0.56TiO3 powder was obtained highly pure, which has a single phase with a monoclinic structure. Replacing In ions with Ti ions change the crystal structure because of the coordination numbers, in which different cations with different ionic radius are placed in the matrix. Cavitation effects on the powder are very different in the liquid. Both the grain size and its coordination number stay active during the deagglomeration process. The grains with the higher coordination number are harder to break. This effect obviously appeared in the XRD patterns as extra peaks and peak broadening because of the dislocation and the particle size distribution. Broadening the XRD peak width and shape confirmed that doping In changes the crystal lattice because of the crystallite smallness with different sized. (C) 2017 Elsevier B.V. All rights reserved.
