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    Öğe
    Investigation of radiation shielding properties of CeO2 thin films prepared at different molarities
    (Iop Publishing Ltd, 2025) Kanmaz, Imran; Koksal, Oguzkagan; Apaydin, Gokhan; Tomakin, Murat; Cengiz, Erhan
    In this study, CeO2 thin films were produced using the spin coting method, which is one of the sol-gel methods, in six different molarities. X-ray diffraction (XRD) patterns revealed the characteristic peaks of the films, while Field Emission Scanning Electron Microscopy (FESEM) confirmed their homogeneous structure. Then, radiation shielding parameters like linear absorption coefficient (LAC), mass absorption coefficient (MAC), tent value layer (TVL), mean free path (MFP), and half value layer (HVL) were thoroughly examined. The results showed that increasing molarity had a significant effect on the thickness values of thin films and the absorption parameters were found to improve with increasing molarity. Both LAC and MAC values decrease as the energy level increases, but the increase in CeO2 molarity leads to a strong increase on these coefficients. The HVL value was also found to be 0.42 cm at the lowest energy of 14.957 keV and to be around 10 cm at the greatest energy of 59.543 keV (0.05 M). When the radiation energy applied to the material was raised from 14.957 keV to 59.543 keV, it was found that the MFP values of 0.05 M CeO2 thin films grew gradually from 0.61 cm to 14.51 cm. High energy radiation of 59.543 keV and a low density (0.05 M) medium resulted in peak TVL values of 33.423 cm, allowing the radiation to pass through the material with minimal interaction.
  • [ X ]
    Öğe
    Thickness-Dependent Structural and Electronic Properties of HfO2 Thin Films Probed by XRD and XAFS
    (Springer, 2025) Ozkendir, Osman Murat; Cengiz, Erhan; Kanmaz, Imran; Gunaydin, Selen; Apaydin, Gokhan; Harfouche, Messaoud
    Hafnium dioxide (HfO2) thin films have garnered significant attention due to their exceptional dielectric, mechanical, and thermal properties, making them ideal for applications in microelectronics, optoelectronics, and energy storage. However, despite extensive research, a comprehensive understanding of their thickness-dependent structural and electronic properties remains incomplete. In this study, we systematically investigate HfO2 thin films (13-115 nm) synthesized via spin coating and characterized using synchrotron-based x-ray absorption fine structure (XAFS) spectroscopy and x-ray diffraction (XRD). High-resolution XRD confirms the monoclinic P2(1)/c phase with high crystallinity and minimal strain, while XAFS analysis reveals thickness-dependent variations in local atomic coordination and electronic structure. XANES spectra demonstrate a systematic shift in the Hf L-3-edge white line, indicating modifications in unoccupied Hf 5d states due to changes in oxygen coordination. EXAFS fitting further quantifies bond distances and coordination numbers, revealing enhanced structural ordering in thicker films. Density functional theory (DFT) calculations corroborate experimental findings, confirming the bandgap (similar to 4.4 eV) and orbital contributions to valence and conduction bands. Our results provide critical insights into defect states, interfacial effects, and thickness-dependent structural modifications, advancing the optimization of HfO2 for next-generation electronic devices.