Browsing by Author "Özkan, DÇ"

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    Synthesis and characterizations of sol-gel derived LaFeO3 perovskite powders
    Özkan, DÇ; Türk, A; Çelik, E
    In this study, LaFeO3 perovskite powders were prepared via the sol-gel method in two different annealing temperatures (500 and 850 degrees C-according to DTA/TG results) for use in dye-sensitized solar cell applications. The thermal, structural, microstructural, particle size, optical and magnetic properties of the samples were characterized by differential thermal analysis (DTA)/thermogravimetric analysis (TG), Fourier transforms infrared spectrometer (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), particle size analysis (PSA), UV-Vis spectrometer and vibrating sample magnetometer (VSM). Our XRD findings show that the as-synthesized powders have an excellent crystallinity, and Scherrer's Equation is used for the estimation of crystallite sizes (within 26-29 nm). Samples were analyzed to reveal the valence states of elements through XPS. Survey scan XPS spectra and high-resolution XPS spectra of La-3d5 and Fe-2p for LaFeO3 samples are given. SEMs employed to observe surface morphologies of all xerogel and ceramic perovskite powder materials and SEM images were verified with PSA results. UV-Vis spectrometer analysis results show that the optical bandgap values (E-g) as measured on both particles were found 2.42 eV. In addition to all analyses, the powders show ferromagnetic behavior, and VSM analyses are used to determine ferromagnetic properties. These results, especially low bandgap, make LaFeO3 powders possible to further increase the performance and efficiency of perovskite-based cells.
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    Synthesis and characterizations of LaMnO3 perovskite powders using sol-gel method
    Özkan, DÇ; Türk, A; Celik, E
    The present research demonstrates the synthesis and characterization of LaMnO3 perovskite powders using the sol-gel technique for solar cell applications. With this respect, LaMnO3 powders were synthesized at two different annealing temperatures by the sol-gel method using La- and Mn-based precursors. Thermal, structural, microstructural, optical and magnetic properties of the powders were characterized through differential thermal analysis-thermogravimetry (DTA-TG), Fourier transform infrared (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), Malvern zeta sizer (PSD), UV-Vis spectrometer and vibrating sample magnetometer (VSM). LaMnO3 was synthesized successfully at 500 degrees C and 850 degrees C synthesis temperatures, and the bandgap was determined as 1.27 eV for both. The analysis revealed that magnetic properties, crystalline and particle sizes change according to the heat of synthesis. The obtained results indicate promise, especially the low bandgap, that LaMnO3 powders can be used in solar cell applications and can positively affect performance and efficiency.
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    Synthesis and characterization of sol-gel derived LaFe0.5Mn0.5O3 perovskite powders for dye-sensitized solar cell applications
    Özkan, DÇ; Türk, A; Çelik, E
    In the present work, structural, microstructural, thermal, magnetic and optical properties of LaFe0.5Mn0.5O3 prepared perovskite powders were exclusively compared for processing temperatures for applications of dye-sensitized solar cells. In this framework, LaFe0.5Mn0.5O3 perovskite powders were synthesized with the sol-gel method at 500 degrees C and 850 degrees C (according to DTA/TG results). They were characterized through DTA/TGA (Thermogravimetric and Differential Thermal Analysis), FTIR (Fourier Transformed Infrared Spectroscopy), XRD (X-Ray Diffractometer), XPS (X-Ray Photoelectron Spectroscopy), PSA (Particle Size Analysis), SEM (Scanning Electron Microscopy), VSM (Vibrating Sample Magnetometer) and UV-Vis Spectrometer. In line with the obtained results, ferroelectric perovskite powders were successfully produced. These powders have crystallite sizes of 27.38-35.74 nm, bandgap values of 1.19-0.93 eV, particle sizes of 28-358 nm and ferromagnetic properties. In addition to the effect of synthesis temperature on LaFe0.5Mn0.5O3 synthesis with these characterization processes, it was found that the production of sustainable and applicable dye-sensitized solar cells using LaFe0.5Mn0.5O3 powders can be useful as innovative and futuristic approaches.