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- MakaleYalnız künye2020Graphene Additives Effect on Mechanical and Structural Characterization Properties of Polyvinyl Alcohol (PVA) and Boron Based Cement Mortar
Çaglar, Hakan; Çaglar, Arzu; Can, Omer
In this study, it was aimed to develop properties of cement paste having standard properties and produce a graphene doped Polyvinyl Alcohol (PVA) and boron-based cement paste in this context. This type of special cement is mixed with PVA as polymer additive material so it can have a higher strength and sufficient elasticity per unit weight. Also, boric acid which can absorb neutrons having poisonous effect in nuclear reactions is added into the cement in order to minimize environmental disaster caused by a nuclear accident. Compressive and bending strengths were measured based on TSE tests of graphene doped PVA and boron-based cement paste. Then, samples were measured by Brunauer-Emmett-Teller Method (BET) and subjected to X-ray Diffraction (XRD). In XRD measurements, crystalline structure was observed in all materials. According to compressive strength tests, as the graphene amount increases compressive strength also increases, however in bending strength tests as the graphene amount increases bending strength decreases. Although the values of bending strength of samples produced decreased with increase of graphene content, these values were found to be above the standard values. In addition to boron, graphene admixture has a significant effect on material with its positive strength properties.
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İncele - MakaleYalnız künye2016The Effects of Boron Alloying on the Structural and Optical Properties of GaAs Deposited by a Thermionic Vacuum Arc Method
Pat, Suat; Korkmaz, Sadan; Özen, Soner; Senay, Volkan
This study reports the influence of the boron alloying on the structural and optical properties of GaAs compound for the first time. UV-Vis-NIR spectrophotometer, interferometer, photoluminescence spectrophotometer, X-ray diffraction, field emission scanning electron microscopy, and atomic force microscopy tools were used for the determination of the structural and optical properties. As results, boron atoms affect the bang gap to upper energy level with very small variations. But, structural properties and grain dimensions of GaAs have improved by adding boron atoms. The results show that used method, thermionic vacuum arc, is the fast, direct, environmental and very easy-doped BGaAs ternary compounds deposition method according to other methods. Finally, this method is a promising method for GaAs technology.
AtıfWoS2OpenAlex4İncele - MakaleAçık Erişim2015Optical, Structural and Morphological Characterization of a Zn-Doped GaAs Semiconducting Thin Film Produced by Thermionic Vacuum Arc
Senay, Volkan; Özen, Soner; Pat, Suat; Korkmaz, Sadan
A 780 nm thick Zn-doped GaAs p-type semiconducting film was deposited onto a glass substrate under a high vacuum condition by means of the thermionic vacuum arc technique in a very short period of time (90 sec) using GaAs and Zn pellets as source materials. In order to characterize the produced film, the optical constants and absorbance of the film were measured using optical methods. By using the obtained optical absorbance data, the optical band gap was estimated from the Tauc plot based on the relation (alpha hv)(2) = B(hv - E-g). The refractive index value of the film was 3.73 at lambda = 632.8 nm. The band gap was estimated to be 1.35 eV. According to the results obtained from the FESEM and AFM related studies, the produced film displayed a granular surface morphology with a root mean square roughness of 17 nm. Contact angle measurements of several testing liquids were used to characterize the film in terms of wettability. It was found that the contact angle value was dependent on the liquid used. However, the film was hydrophilic as observed in contact angle measurements.
AtıfWoS3OpenAlex3İncele - MakaleAçık Erişim2011Scopus SJRQ2Airy's functions in nonlocal elasticity
Altan, Burhanettin S.
Nanostructured devices and materials, such as carbon nanotubes, Atomic Force Microscope, MEMS, etc. attract increasing attention in the scientific world. It has been realized that the classical elasticity is not capable to capture the mechanical behavior of them precisely. There is a wide consensus among the scientists that nonlocal elasticity is more capable than the classical counterpart to model the mechanical behavior of nanostructured materials and devices. In this paper a method which is useful for solving problems in nonlocal is introduced. Airy's stress functions for plane stress problems in nonlocal elasticity are studied. The nonlocal constitutive equations in integral form are discussed and a method is suggested to invert the constitutive equation which allows expressing strains in terms of stresses. A qualitative discussion is given on this inversion process. For the nonlocality kernel of exponential form, the differential equation for Airy's functions in nonlocal elasticity is obtained by introducing the strains into the compatibility condition. Appropriate polynomial forms for the Airy's function are considered and are applied to solve beam bending problems. The solutions are compared with their classical counterparts. The results are given in a series of figures and tables and are discussed in detail. This paper is concluded by indicating the implications of the presented study in nanomechanics and nanotechnology.
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