Recep Tayyip Erdoğan Üniversitesi Kurumsal Akademik Arşivi
DSpace@RTEÜ, Recep Tayyip Erdoğan Üniversitesi tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve yayınların etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Sustainable lead-free Na2AgSbX6 (X = Cl, F) double perovskites with tunable optoelectronic and thermoelectric properties: A first-principles study
(Elsevier, 2026) Bouferrache K.; Ghebouli M.A.; Fatmi M.; Alanazi, Faisal K.; Saidi, Samah; Alomairy S.; Yaylacı, Murat
Lead-free halide double perovskites have emerged as promising candidates for sustainable energy technologies due to their low toxicity and structural stability. In this work, we investigate the structural, electronic, optical, and thermoelectric properties of Na2AgSbX6 (X = Cl, F) using density functional theory. Both compounds crystallize in a stable cubic Fm-3m structure, with tolerance factors (0.808–0.829) confirming their structural feasibility. The calculated indirect band gaps of 2.398 eV (Cl) and 4.11 eV (F) reveal tunable optoelectronic behavior spanning the visible to ultraviolet regions. Optical analysis demonstrates strong light absorption with low reflectivity, highlighting their suitability for photovoltaic applications. Furthermore, the compounds exhibit favorable Seebeck coefficients and promising thermoelectric performance with ZT values approaching technologically relevant ranges. The combination of environmental compatibility, tunable electronic structure, and multifunctional energy conversion capabilities positions Na2AgSbX6 double perovskites as attractive candidates for next-generation sustainable photovoltaic and thermoelectric devices.
Annealing-tailored visible photodetection performance of Sb2S3 thin films deposited by E-beam evaporation
(Elsevier, 2026) Yılmaz S.; Olğar M.A.; Rehman F.; Bayazıt, Tuğba; Küçükömeroğlu T.; Bacaksız E.
Sb2S3 thin films were deposited on glass substrates by electron-beam (e-beam) evaporation and subsequently annealed at 250°C, 300°C, and 350°C in a sulfur–argon atmosphere using a rapid thermal annealing (RTA) process. The effects of annealing temperature on the structural, morphological, optical, and photodetection properties of the films were systematically investigated. X-ray diffraction (XRD) and Raman spectroscopy analyses revealed that the as-deposited Sb2S3 films were amorphous, whereas the annealed films exhibited a polycrystalline orthorhombic Sb2S3 structure with progressively improved crystallinity at higher annealing temperatures. Scanning electron microscopy (SEM) observations indicated significant grain growth following annealing, while X-ray photoelectron spectroscopy (XPS) confirmed the formation of Sb2S3 with Sb3+ chemical states and revealed a sulfur-deficient surface composition. Optical measurements showed that the optical band gap decreased from 1.95 eV for the as-deposited film to approximately 1.74 eV after annealing, which can be associated with improved crystallinity and reduced structural disorder. Photodetectors with an Ag/Sb2S3/Ag configuration were fabricated, and their photoresponse characteristics were evaluated under blue (443 nm) and red (625 nm) illumination. The device fabricated using the Sb2S3 film annealed at 350°C exhibited the highest photosensitivity values of 5553% and 6302% under blue (16 mW/cm2) and red (14 mW/cm2) illumination, respectively, together with stable switching behavior. For the same device, the maximum responsivity (R) reached 47.72 μA/W under red illumination (5 mW/cm2), while the shortest rise and decay times were 8 ms and 12 ms, respectively. In addition, the photodetector fabricated from the film annealed at 350°C achieved a maximum detectivity (D*) of 7.3 × 108 Jones under red illumination at 14 mW/cm2. The improved photodetection performance is correlated with the enhanced crystallinity, and reduced structural disorder induced by sulfur-assisted annealing. These results demonstrate that e-beam-evaporated Sb2S3 thin films are promising candidates for visible-light photodetector applications.
Mechanical and microstructural performance evaluation for cement-based mortar: calcined mud powder
(Nature Research, 2026) Kurt, Zafer
Although there are ongoing studies on innovative green materials, building materials are mostly composed of cementitious compounds as binders. Cement is known to significantly increase CO2 emissions both during its production and utilization. Furthermore, while the utilization of industrial by-products in waste storage and disposal processes offers positive contributions to the circular economy, this approach does not constitute a holistic and adequate solution in terms of the environment and human health. This study presents the results of the effect of mud powder obtained from Rize province on the mechanical and microstructural properties of cement mortars to the academic environment. The mud was dried and ground, then calcined at 600, 700 and 800 °C. The calcined mud powder obtained at the optimum calcination temperature was substituted into cementitious mortars at 0%, 10%, 20%, 30% and 40% by weight. The parameters used in the study were material/ball weight = 1/12 and binder/cement weight = 0.45. Compressive and flexural tests were performed for mechanical strength and XRD, SEM–EDS, FTIR, Specific gravity, and UPV tests were performed to explain the microstructures. The numerical and test data imply that the maximum 28-day compressive strength of 46. 65 MPa was obtained as a result of 10% substitution of calcined mud powder, which is a natural resource. These results indicated that calcined powder mud (CPS) has strong potential as a sustainable material for construction and structural applications.
Boyalar ve Badanalar
(2026) Güner, Mehmet Selçuk
Malzeme Bilimi Ders Notu Konusu : Boyalar ve Badanalar
