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- MakaleYalnız künye2025Scopus SJRQ1Evaluation of the optical, structural, and morphological characteristics of a Sn-doped α-Fe2O3 thin film fabricated using RF and DC magnetron Co-sputtering technique
Salari, Maryam Abdolahpour; Şenay, Volkan; Muğlu, Günay Merhan; Sarıtaş, Sevda; Kundakçı, Mutlu
In this research, a Sn-doped hematite (α-Fe2O3) thin film on a glass substrate was synthesized using DC and RF magnetron sputtering techniques, and the physical features of the film were analyzed in detail. This study, conducted to investigate the effects of Sn doping on the hematite structure, evaluated the optical and morphological attributes of the thin film using advanced characterization techniques such as UV–VIS spectroscopy, Raman spectroscopy, XRD, SEM, EDS, and AFM. The optical band gap was determined from absorption measurement and calculated to be 2.12 eV. Raman spectroscopy results revealed various characteristic peaks between 100 cm−1 and 1500 cm−1. A strong (214) diffraction peak confirms the enhanced hematite phase formation in the thin film. The crystallite size of the Sn-doped thin film, calculated via Scherrer's formula, is 20 nm. SEM images showed that the thin film exhibited a smooth and homogeneous surface morphology on the glass substrate. According to the EDS results, the atomic doping ratio of Sn in Fe2O3 is 2.84 %. Additionally, AFM analysis confirmed that the Sn-doped α-Fe2O3 thin film had a smooth surface, as indicated by a low RMS (Root Mean Square) roughness value of 8.11 nm. These properties suggest that the thin film could be suitable for optoelectronic applications. The study emphasizes the potential of Sn-doped α-Fe2O3 thin films, particularly for optoelectronic and photocatalytic devices, and underscores the need for further investigation of these materials. Furthermore, it was concluded that these materials should be considered in a broader context for their potential use in various technological applications.
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İncele - MakaleAçık Erişim2024Scopus SJRQ2Optical, structural, morphological, and gas sensing properties of Mg-doped α-Fe2O3 thin films deposited by RF and DC magnetron Co-sputtering technique
Sarıtaş, Sevda; Merhan Muğlu, Günay; Turgut, Erdal; Kundakçı, Mutlu; Yıldırım, Muhammet; Şenay, Volkan
In this research, Mg-doped hematite (α-Fe2O3) thin films with different Mg-doping concentrations were synthesized on glass substrates using the direct current (DC) and radio frequency (RF) magnetron co-sputtering technique, and the changes of some physical properties due to the concentration of the dopant were investigated. The optical, structural, morphological, and elemental properties of the obtained Mg-doped α-Fe2O3 thin films were determined by X-ray diffraction (XRD) analysis, UV–Vis spectroscopy, Raman spectroscopy, scanning electron microscopy (SEM), dispersive X-ray spectroscopy and atomic force microscopy (AFM). XRD analysis revealed that the investigated thin films have a rhombohedral crystal structure. The deposition of films at different DC sputtering voltages caused significant variations in stoichiometry and nanostructure. The thin films' band gap energy values were estimated based on absorption measurements, and results ranged from 2.15 eV to 2.69 eV. Raman peaks were observed between 218 cm−1 and 1305 cm−1. The thin films exhibit uniform surface morphology throughout the substrate according to the SEM images. The low RMS roughness values obtained from AFM images showed that the surfaces of Mg:Fe2O3 thin films are smooth. The Mg-doped α-Fe2O3 thin film doped by 150 W DC voltage exhibited a good gas-sensing response at 300 °C. A remarkably quick response/recovery time was achieved.
AtıfScopus19WoS13OpenAlex20İncele - MakaleAçık Erişim2024Scopus SJRQ1Analysis of optical, structural, and morphological properties of a Ti-doped α-Fe2O3 thin film produced through RF and DC magnetron Co-sputtering
Abdolahpour Salari, Maryam; Merhan Muğlu, Günay; Şenay, Volkan; Sarıtaş, Sevda; Kundakçı, Mutlu
In this study, a Titanium (Ti) doped α-Fe2O3 (hematite) thin layer was synthesized onto a glass substrate, employing the simultaneous DC and RF magnetron sputtering method. The investigation focused on examining specific physical properties of the film. The optical, structural, morphological, and elemental features of the resulting Ti-doped α-Fe2O3 thin film were characterized using different characterization techniques. The XRD studies indicated a rhombohedral crystal structure in the studied thin film. The calculation of the Eg value for the thin film, based on absorption measurements, resulted in a value of 2.19 eV. Raman peaks were identified within the range of 218 cm−1 to 1300 cm−1. According to SEM images, the thin film exhibited a uniform surface morphology across the substrate. AFM images revealed a low root mean square (RMS) roughness value, indicating a smooth Ti:Fe2O3 thin film surface.
AtıfScopus24WoS25OpenAlex29İncele - MakaleAçık Erişim2022Scopus SJRQ3A comparative characterization study between fungal and bacterial eumelanin pigments
Bayram, Sinan
Melanins are the most common and the most enigmatic natural pigments in the nature that found in many different taxa group such as bacteria, yeasts, fungi, insects, plants, reptiles, birds and mammals. These biological macromolecules are highly complex cross-linked, heterogeneous biopolymers and composed of polymerized phenolic and/or indolic compounds. Recently, interest in these ubiquitous biopolymers has been increasing considerably in many different areas such as medicine, pharmacology, cosmetics, organic electronic and optoelectronics because of their versatile properties. In this study, four different extracellular eumelanin pigments (two bacterial eumelanins and two fungal eumelanins) were characterized by different spectrometric techniques such as FT-IR, XRD, NMR and UV-vis. In XRD analyzes, purified fungal and bacterial eumelanin pigments were characterized by giving a wide peak at about 22o with an angle of 2θ. Furthermore, in the 1 H NMR spectra of these biopolymers, it was observed that all pigments have signals in both aromatic and aliphatic regions. In addition to these analyzes, nanostructures of these biopolymers were characterized using atomic force microscopy (AFM) and scanning electron microscopy (SEM). Finally, eumelanin pigment producer microorganisms were molecularly characterized. 16 S rDNA and 18 S rDNA sequence analysis results of these microorganisms (Streptomyces fulvissimus MPPS4, Streptomyces xiamenensis MPPS6, Aspergillus niger MPPF16 and Aspergillus terreus MPPF25) were deposited in NCBI GenBank® database with accession number MT825594, MT973972, MW652652 and MW652653 respectively.
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İncele - MakaleYalnız künye2022Scopus SJRQ2Brand portfolio strategies effects on consumers' attitude
Yilmazel, Sefa Emre; Özer, Leyla
Purpose: The aim of this study is to determine the effects of brand components (CBBE, brand fit, brand image, brand reputation, brand familiarity) on consumers brand portfolio attitude via perceived risk (for two main portfolio strategies). Design/methodology/approach: The study used a structured questionnaire to collect primary data from 636 consumers who made purchases from companies using house of brand (318) and branded house strategy (318). By conducting reliability and validity analysis, the model of this study was tested with confirmatory factor analysis and path analysis methods, using structural equation modeling. Findings: According to the results of the path analysis, the effects of CBBE and brand reputation on brand attitude were confirmed for both house of brand and branded house strategy. Moreover, the full and partial mediating effect of perceived risk was proven in the relationships. Research limitations/implications: One of the limitations of the study is determining a portfolio of brands for each strategy and collecting data for these brands. In addition, since the number of consumers using brand portfolios could not be reached in the study, data could be collected using the purposeful convenience sampling method. For this reason, it is thought that research conducted with the data obtained through systematic sampling methods can yield more reliable results. Practical implications: Managers of companies with a brand portfolio should work on a main strategy that enhances CBBE and brand reputation regardless of the strategy they use. After these two variables, the variable that portfolio managers need to address is brand fit. Originality/value: It will offer different perspectives in terms of understanding which portfolio strategy is needed, and which predecessors and outputs can be produced. Also, the findings of the research will produce important results to reduce the perceived risks of consumers and increase their positive attitudes toward brand portfolios.
AtıfScopus7WoS6OpenAlex8İncele - MakaleYalnız künye2012Scopus SJRQ1Determination of the effect of volcanic pumice replacement on macro void development for blended cement mortars by computerized tomography
Tekin, Ilker; Birgul, Recep; Aruntas, Huseyin Yilmaz
In this study, the effect of volcanic pumice replacements with different ratios on the macro void development was observed using CT for a period of 100 days. The cured mortar specimens were imaged by X-ray CT on different days of the experiment. Utilizing Hounsfield Unit values as guides, void volumes and ratios were identified and measured by Matlab software. SEM images supported the X-ray CT results. It is shown that X-ray CT analysis is capable of assessing the development of macro voids in the mortar specimens.
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