Sürdürülebilir Kalkınma Amaçları

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• MakaleYalnız künye2027Scopus SJRQ2/r/munzur/1135
  Design, structural characterization, and simulated radiation-transport assessment of high-entropy (GdErSmEuYb)2X2O7 (X = Hf, Zr, Ce, Si) rare-earth oxides

  Güler, Ömer; Güler, Seval Hale; Yayla, Nihal; Baykal, Duygu Sen; Durmus, Hasan; Tekin, Huseyin Ozan; ALMisned, Ghada

  This study investigates the structural, microstructural, surface-chemical, and radiation attenuation behaviour of high-entropy rare-earth oxide (HEO) powder compositions synthesized as TBC-related candidate coating materials, whose radiation attenuation potential was assessed within a computational Inconel-718-based sandwich model. Four compositions, namely (GdErSmEuYb)2Hf2O7, (GdErSmEuYb)2Ce2O7, (GdErSmEuYb)2Zr2O7, and (GdErSmEuYb)2Si2O7, were synthesized via high-energy ball milling followed by calcination at 1200 °C. X-ray diffraction results revealed the formation of distinct crystal structures depending on B-site chemistry, including defective fluorite and silicate-type phases. SEM-EDS mapping confirmed homogeneous elemental distribution, while XPS analysis demonstrated mixed valence states and different oxygen vacancy concentrations across the compositions. To evaluate radiation attenuation performance, a sandwich-type geometry consisting of a 10 mm Inconel-718 core with symmetrically defined simulated HEO layers was modelled using Monte Carlo simulations. Gamma-ray transmission was analyzed over an energy range of 0.276-1.332 MeV, and fast neutron attenuation was assessed at 4.5 MeV. The results showed that transmission factors decreased with increasing coating thickness, with the effect being more pronounced at lower photon energies. Among the investigated compositions, the Hf-based system exhibited the most favorable predicted attenuation response for both gamma rays and fast neutrons under the defined simulation conditions. Theoretical half-value layer calculations also showed good agreement with the simulation results. Overall, the findings indicate that high-entropy rare-earth oxide coatings may provide an additional radiation attenuation contribution when incorporated as layers in Inconel-718-based systems. However, since direct thermal-barrier properties such as thermal conductivity, thermal diffusivity, thermal cycling resistance, and thermal-stress behavior were not evaluated in the present work, the present study should be interpreted as a structural and radiation-transport assessment of TBC-related coating candidates rather than a direct demonstration of thermal-barrier performance.

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• MakaleAçık Erişim2026Scopus SJRQ1/r/munzur/1361
  Comparative effects of La2O3 and Sm2O3 on structural and radiation shielding properties of WO3 enriched borate glassy-ceramics

  Taşgın, Yahya; Yılmaz, Demet; Kanca, M. Sait; Yayla, Nihal; Kök, Mediha; Güler, Ömer

  This research comprehensively investigates the impact of incorporating rare earth oxides ‑samarium oxide (Sm2O3) and lanthanum oxide (La2O3)- into a borate glassy-ceramic system enriched with tungsten oxide (WO3), with a focus on both structural characteristics and radiation shielding performance. SEM-EDS, elemental mapping, and XRD analyses conducted on the synthesized glassy-ceramic samples revealed that the incorporated rare earth oxides, Sm2O3 and La2O3, were uniformly distributed throughout the glassy-ceramic matrix. The results also confirmed that the glassy-ceramic retained its inherently amorphous structure. Moreover, the nominal doping levels of the rare earth elements were found to be in agreement with both the qualitative and quantitative results obtained from EDS measurements. Also, the gamma ray shielding parameters of synthesized glassy-ceramic samples were measured in absorption geometry with Am-241, Ba-133 and Ra-226 radioactive sources. The neutron shielding parameters were theoretically calculated. The 241Am-Be fast neutron source was used to measure the equivalent dose of neutron absorption. At an incident photon energy of 74.8 keV, the mass attenuation coefficient of the tungsten oxide–enriched borate glassy-ceramic exhibited a remarkable improvement—rising by 17.98 % with the addition of 3 wt% Sm2O3 and by 11.58 % with the addition of 3 wt% La2O3. Notably, the N4 sample demonstrated a significant reduction in neutron-equivalent dose rate, reaching 19.80 % (μSv/h). The lead equivalent thicknesses (Pbeq) calculated at 356 keV were 0.02397 cmPb for N0, 0.0391 cmPb for N1, 0.0403 cmPb for N4, and 0.0389 cmPb for N7. When benchmarked against the undoped N0 sample, the N4 and N7 compositions exhibited reductions in Pbeq values by approximately 68 % and 62 %, respectively, indicating a marked improvement in gamma shielding efficiency. Among all tested formulations, the Sm2O3-doped variant demonstrated superior gamma-ray attenuation capability relative to the La2O3-doped glassy-ceramic. Furthermore, the N4 sample achieved an impressive thermal neutron attenuation rate of 96.46 %, underscoring its strong potential as an effective dual-purpose shielding material against both thermal neutrons and ionizing gamma radiation.

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• MakaleAçık Erişim2026Scopus SJRQ2/r/munzur/1194
  Enhanced Radiation Shielding and Structural Modifications in Samarium (III) Oxide-Reinforced Type 316L Stainless Steel Composites for Nuclear Applications: A Comprehensive Evaluation of Physical, Structural, Mechanical, Gamma-Ray, and Neutron Attenuation Properties

  Yayla, Nihal; Albayrak, M. Gökhan; Güler, Ömer; Sen Baykal, Duygu; Alkarrani, Hessa; ALMisned, Ghada; Tekin, H.O.

  Type 316L stainless steel (316L-SS) is widely recognized for its exceptional corrosion resistance, making it a preferred material in various industries. However, conventional stainless steel materials are inadequate for radiation shielding applications. While oxide dispersion-strengthened alloy composites with a 316L-SS matrix have been extensively studied in the literature for their mechanical creep properties, their radiation shielding capabilities remain insufficiently explored. This study investigates the potential of samarium oxide (Sm2O3) doped to improve the structural, physical, mechanical, and radiation shielding properties of 316L-SS composites. Samples containing 1%, 5%, 10%, and 20% Sm2O3 by weight were synthesized and extensively characterized using X-ray diffraction and scanning electron microscopy. These analyses revealed enhanced homogeneity and refined grain structure with increasing Sm2O3 content. Gamma-ray and neutron shielding properties demonstrated significant improvements, particularly in composites with 20% Sm2O3 reinforcement, as evidenced by lower half-value layer and mean free path values, along with an increased fast neutron removal cross section. However, a trade-off was observed between radiation shielding performance and mechanical properties: As the Sm2O3 content increased, the elastic modulus decreased, indicating reduced stiffness due to the incorporation of Sm2O3. This trade-off suggests that while Sm2O3 reinforcement effectively enhances radiation shielding, it may not be ideal for structural applications requiring high mechanical strength. Nevertheless, these findings highlight the potential of Sm2O3-doped 316L-SS composites for nonstructural radiation protection systems, particularly in applications where improved shielding performance is prioritized over mechanical stiffness.

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• MakaleAçık Erişim2026Scopus SJRQ1/r/munzur/1177
  Radiation shielding performance of (SmEuYbLaEr)2TaO4 high-entropy oxide reinforced Cu matrix composites

  Taşgın, Yahya; Yılmaz, Demet; Kanca, M. Sait; Kök, Mediha; Yayla, Nihal; Güler, Ömer

  High-entropy oxides (HEOs) containing rare earth elements are attracting increasing interest due to their thermal stability and potential for use in radiation shielding applications. In this study, the high-entropy oxide (SmEuYbLaEr)2TaO4 was synthesized via mechanical alloying (MA) followed by calcination and incorporated into a Cu matrix at different reinforcement levels to produce volumetric composites. Structural, thermal, and microstructural analyses confirmed the successful formation of a stable HEO phase and its effective dispersion within the Cu matrix. The radiation shielding performance of the composites was experimentally evaluated over a wide range of photon energies using standard gamma-ray sources. The results showed that shielding performance depends largely on both photon energy and HEO content. Increasing the HEO concentration significantly reduced the half-value layer (HVL) while substantially increasing the mass attenuation coefficient (MAC) and radiation protection efficiency (RPE), particularly in the low- and medium-energy regions where the photoelectric effect is dominant. Among the materials studied, the Cu composite containing 20 wt% HEO exhibited the best overall shielding performance. These results demonstrate that (SmEuYbLaEr)2TaO4 is an effective additive for improving the radiation shielding capability of Cu-based composites and highlight its potential for advanced radiation protection applications.

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• MakaleYalnız künye2026Scopus SJRQ2/r/munzur/967
  Manufacturing, Structural Characterization, and Radiation Interaction Evaluation of Lightweight 6061-Al/Ytterbium(III) Oxide Composites with Emphasis on Gamma-Ray Shielding and Fast Neutron Removal Potential

  Guler, Seval Hale; Yayla, Nihal; Guler, Omer; ALMisned, Ghada; Sen Baykal, Duygu; Kilic, Gokhan; Tekin, Huseyin Ozan

  In this study, 6061-aluminum metal matrix composites doped with varying concentrations of ytterbium(III) oxide were synthesized using high-energy mechanical alloying to evaluate their structural, physical, and radiation shielding properties. X-ray diffraction confirmed the retention of the aluminum crystal structure with no secondary phase formation, while scanning electron microscopy and energy-dispersive X-ray spectroscopy revealed homogenous dispersion of Yb2O3 particles within the matrix. With increasing Yb2O3 content, particle densification and structural integrity were significantly enhanced. Gamma-ray and neutron shielding performance was assessed through theoretical modeling and Monte Carlo simulations. At low photon energy, the 20 wt% Yb2O3 composites showed a remarkable increase in linear attenuation coefficients compared to the undoped 6061-aluminum matrix. Neutron removal efficiency also increased by 32% at the highest Yb2O3 content. It can be concluded that Yb2O3 incorporation significantly improves both the photon and neutron shielding performance of the 6061-aluminum metal matrix.

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• MakaleAçık Erişim2025/r/munzur/6014
  Investigation of the Bioactivity Properties of TiZrCrNb0.3Ta0.07 Medium Entropy Alloy Produced from TNTZ Waste

  Say, Yakup; Yayla, Nihal; Güler, Ömer; Güzel, Harun

  High entropy alloys (HEAs) and medium entropy alloys (MEAs) have garnered significant attention as alternative materials in various fields due to their superior physical and chemical properties compared to conventional alloys. One of the most promising applications of this innovative material class is in biomaterials. In this study, a bio-medium entropy alloy (BioMEA), TiZrCrNb0.25Ta0.05, was successfully synthesized using non-toxic elements (Ti, Zr, Cr, Nb and Ta) through arc melting of TNTZ alloy waste. The produced BioMEA was comprehensively characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD) to analyze its structural and chemical properties. Additionally, the in-vitro degradation, ion release, and bioactivity properties of the alloy were evaluated and compared with those of the conventional TNTZ alloy, with a focus on the effects of heat treatment. The results demonstrated that heat treatment did not cause significant changes in the microstructure of the TiZrCrNb0.25Ta0.05 alloy but led to the formation of intermetallic compounds such as Cr2Zr and Cr2Ta on the surface. Degradation tests revealed an unexpected mass gain across all sample groups after a four-week immersion period due to surface precipitation, surpassing the expected mass loss from degradation. Ion release analyses showed similar behavior between the TiZrCrNb0.25Ta0.05 and TNTZ alloys, with ion release levels in the ppb range, confirming that Ti was released at non-toxic levels. Bioactivity tests identified low lesvels of Ca-P-O deposition on all sample surfaces, with the highest bioactivity observed in the heat-treated TiZrCrNb0.25Ta0.05 sample. Overall, the findings suggest that the TiZrCrNb0.25Ta0.05 alloy has the potential to serve as an alternative biomaterial to the TNTZ alloy, with its bioactivity properties being further enhanced through heat treatment. Further studies are recommended to optimize its bioactivity and evaluate its in-vivo performance for biomedical applications.

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• MakaleAçık Erişim2025Scopus SJRQ2/r/munzur/1977
  Dual-effect of Holmium(III) oxide and Boron Carbide reinforcement on physical, microstructural evolution and gamma-ray shielding performance of 316L-SS

  Yayla, Nihal; Albayrak, M. Gökhan; Güler, Ömer; Almisned, Ghada; Sen Baykal, Duygu; Alkarrani, Hessa; Kilic, Gokhan; Tekin, Huseyin Ozan

  This study provides one of the first comprehensive evaluations of 316L stainless steel composites reinforced with 10 wt.% B4C and varying concentrations of Ho2O3, proposing a new compositional design for simultaneous structural enhancement and dual gamma-neutron shielding optimization. XRD analysis confirmed the predominance of the austenitic phase with minor martensitic peaks at higher Ho2O3levels. SEM and EDX results revealed uniform dispersion and improved densification with increasing oxide content. The 316L-B4C-20%Ho2O3composite exhibited the highest mass attenuation coefficient (0.8953 cm2/g) and linear attenuation coefficient (6.73 cm−1) at 0.1 MeV, demonstrating superior gamma-ray shielding capability. The effective electron density increased from 2.86 × 1023to 5.82 × 1023electrons/cm³, while the energy absorption buildup factor (EABF) showed a consistent decrease with higher oxide concentrations. Although a slight reduction in fast neutron removal cross-section was observed, the composite maintained satisfactory neutron attenuation performance. Overall, the findings indicate that the 316L-B4C-20%Ho2O3system offers a promising balance between structural stability and dual radiation protection, making it a strong candidate for next-generation nuclear shielding materials.

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• MakaleAçık Erişim2025Scopus SJRQ1/r/munzur/1588
  Enhanced radiation shielding via incorporating europium oxide in 316L stainless steel: Synthesis, physical, microstructural, shielding, and mechanical properties

  Tekin, H.O.; Yayla, Nihal; Albayrak, M.Gökhan; Güler, Ömer; Baykal, Duygu Sen; Alkarrani, Hessa; ALMisned, Ghada

  316L stainless steel is widely utilized in various industries due to its excellent corrosion resistance, mechanical strength, and biocompatibility, making it a preferred material for applications in nuclear filed. However, enhancing its radiation shielding and mechanical properties through reinforcement strategies, such as the addition of high-Z materials like Europium(III) oxide, is crucial for extending its functionality in high-radiation environments, where improved performance is essential for safety and durability. In this study, 316L stainless steel composites reinforced with varying amounts of Eu2O3 (1%, 5%, 10%, and 20%) were synthesized and investigated for their structural, mechanical, and radiation shielding properties. X-ray diffraction (XRD) analysis revealed that the face-centered cubic (FCC) structure of the steel matrix was preserved up to 5% Eu2O3 reinforcement, while higher concentrations led to phase formation and crystallographic changes. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis showed uniform element distribution at low reinforcement levels, with particle clustering at 20% Eu2O3. Transmission factors (TFs) were evaluated using PHITS simulations for photon energies of 0.662 MeV, 1.1732 MeV, and 1.3325 MeV. The 20% Eu2O3 composite exhibited the lowest TF and highest attenuation properties, confirmed by mass and linear attenuation coefficients. Elastic modulus values decreased from 224.46 GPa in pure 316L to 189.26 GPa with 20% Eu2O3 reinforcement, reflecting the inverse relationship between mechanical stiffness and radiation shielding performance. Benchmarking against other shielding materials demonstrated superior performance of the Eu2O3-reinforced steel in gamma-ray attenuation. The 20% Eu2O3 composite shows strong potential for applications in nuclear radiation shielding where attenuation efficiency is prioritized over mechanical properties.

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• MakaleAçık Erişim2025Scopus SJRQ2/r/munzur/1516
  Effect of neodymium addition on the structural, mechanical, and magnetic properties of FeCoNiCu(MnCr)0.5 high entropy alloys

  Yayla, Nihal; Şimşek, Telem; Boyrazlı, Mustafa; Güler, Ömer

  Neodymium (Nd), a rare earth element, was incorporated into the [FeCoNiCu(MnCr)0.5] high-entropy alloy (HEA) at weight percentages of 0.5%, 1%, 2%, and 5%. The alloys were synthesized successfully using the arc melting method. X-ray diffraction (XRD) analysis confirmed that both the undoped and Nd-doped alloys exhibit a single-phase solid solution with a face-centered cubic (FCC) crystal structure, consistent with thermodynamic predictions derived from the Miedema model. Scanning electron microscopy (SEM) revealed a dendritic structure in the undoped alloy, which was replaced by Cu- and Cr-rich regions in the 5% Nd-doped alloy, as confirmed by energy dispersive spectroscopy (EDS). Differential scanning calorimetry (DSC) indicated an endothermic peak in the undoped alloy and minor thermal responses in Nd-doped samples, without distinct phase transitions within the 0–800 °C range. Mechanical testing demonstrated substantial enhancements in both hardness and tensile strength with increasing Nd content. The 5% Nd-doped alloy exhibited the highest performance, achieving a Vickers hardness of 370 HV and a tensile strength of 1186 MPa. Magnetic testing indicated ferromagnetic behavior in all samples, with Nd additions significantly enhancing magnetic properties. Notably, the 5% Nd-doped alloy achieved a saturation magnetization (Ms) of 41 emu/g and a coercivity (Hc) of 6.3 Oe, highlighting improved magnetic softness and rapid magnetization loss characteristic of soft magnetic materials.

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• MakaleAçık Erişim2025Scopus SJRQ2/r/munzur/1492
  Synthesis, microstructural refinement, and shielding optimization of Gd2O3-reinforced AISI 316L stainless steel: a multi-dimensional integration assessment for targeted protection applications

  Yayla, Nihal; Albayrak, M Gökhan; Güler, Ömer; Sen Baykal, Duygu; Alkarrani, Hessa; ALMisned, Ghada; Issa, Bashar; Tekin, H.O.

  This study investigates the multi-dimensional effects of increasing Gd2O3 reinforcement on the structural, mechanical, and gamma-ray shielding properties of AISI 316L stainless steel composites. Samples with varying Gd2O3 content (1%, 5%, 10%, and 20% by weight) were synthesized and characterized through x-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) to assess the microstructural changes and homogeneity of Gd2O3 dispersion after mechanical milling. The addition of Gd2O3 significantly enhanced the gamma-ray shielding properties, with the mass attenuation coefficient (MAC), linear attenuation coefficient (LAC), and half-value layer (HVL) improving as the Gd2O3 content increased, particularly in low to moderate photon energy ranges. Simultaneously, the elastic modulus exhibited an inverse relationship, decreasing with higher Gd2O3 content due to the lower stiffness of gadolinium compared to iron. Transmission factor (TF) values also decreased, indicating enhanced photon attenuation with higher Gd2O3 content across various thicknesses. The experimental characterization confirmed improved Gd2O3 dispersion and material uniformity after mechanical milling, contributing to the composites’ superior radiation shielding performance. It can be concluded that Gd2O3-reinforced AISI 316L stainless steel composites offer a promising balance between enhanced radiation shielding properties and reduced mechanical stiffness, making them ideal candidates for applications requiring efficient and adaptable radiation protection especially for portable and non-structural shielding applications.

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