Researcher:
Bateni, Ali

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PhD Student

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Ali

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Bateni

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Bateni, Ali

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2012 - 20195

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Researcher Of Publications: search.filters.isAuthorOfPublication.1332110d-6b04-4d85-9cc8-6ba55c59f672

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Now showing 1 - 5 of 5
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    PublicationOpen Access
    Al-doped MgB2 materials studied using electron paramagnetic resonance and Raman spectroscopy
    (American Institute of Physics (AIP) Publishing, 2016) Erdem, Emre; Repp, Sergej; Weber, Stefan; N/A; Department of Chemistry; Bateni, Ali; Somer, Mehmet Suat; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178882
    Undoped and aluminum (Al) doped magnesium diboride (MgB2) samples were synthesized using a high-temperature solid-state synthesis method. The microscopic defect structures of Al-doped MgB2 samples were systematically investigated using X-ray powder diffraction, Raman spectroscopy, and electron paramagnetic resonance. It was found that Mg-vacancies are responsible for defect-induced peculiarities in MgB2. Above a certain level of Al doping, enhanced conductive properties of MgB2 disappear due to filling of vacancies or trapping of Al in Mg-related vacancy sites. Published by AIP Publishing.
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    PublicationOpen Access
    Defect structure of ultrafine MgB2 nanoparticles
    (American Institute of Physics (AIP) Publishing, 2014) Repp, Sergej; Thomann, Ralf; Acar, Selçuk; Erdem, Emre; N/A; Department of Chemistry; Bateni, Ali; Somer, Mehmet Suat; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178882
    Defect structure of MgB2 bulk and ultrafine particles, synthesized by solid state reaction route, have been investigated mainly by the aid of X-band electron paramagnetic resonance spectrometer. Two different amorphous Boron (B) precursors were used for the synthesis of MgB2, namely, boron 95 (purity 95%-97%, <1.5 mu m) and nanoboron (purity >98.5%, <250 nm), which revealed bulk and nanosized MgB2, respectively. Scanning and transmission electron microscopy analysis demonstrate uniform and ultrafine morphology for nanosized MgB2 in comparison with bulk MgB2. Powder X-ray diffraction data show that the concentration of the by-product MgO is significantly reduced when nanoboron is employed as precursor. It is observed that a significant average particle size reduction for MgB2 can be achieved only by using B particles of micron or nano size. The origin and the role of defect centers were also investigated and the results proved that at nanoscale MgB2 material contains Mg vacancies. Such vacancies influence the connectivity and the conductivity properties which are crucial for the superconductivity applications. (C) 2014 AIP Publishing LLC.
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    PublicationOpen Access
    Electron paramagnetic resonance and Raman spectroscopy studies on carbon-doped MgB2 superconductor nanomaterials
    (American Institute of Physics (AIP) Publishing, 2015) Erdem, Emre; Repp, Sergej; Acar, Selçuk; Kokal, İlkin; Haessler, Wolfgang; Weber, Stefan; N/A; Department of Chemistry; Bateni, Ali; Somer, Mehmet Suat; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178882
    Undoped and carbon-doped magnesium diboride (MgB2) samples were synthesized using two sets of mixtures prepared from the precursors, amorphous nanoboron, and as-received amorphous carbon-doped nanoboron. The microscopic defect structures of carbon-doped MgB2 samples were systematically investigated using X-ray powder diffraction, Raman and electron paramagnetic resonance spectroscopy. Mg vacancies and C-related dangling-bond active centers could be distinguished, and sp(3)-hybridized carbon radicals were detected. A strong reduction in the critical temperature T-c was observed due to defects and crystal distortion. The symmetry effect of the latter is also reflected on the vibrational modes in the Raman spectra. (C) 2015 AIP Publishing LLC.
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    PublicationOpen Access
    High-quality MgB2 nanocrystals synthesized by using modified amorphous nano-boron powders: study of defect structures and superconductivity properties
    (American Institute of Physics (AIP) Publishing, 2019) Erdem, Emre; Hassler, Wolfgang; Department of Chemistry; N/A; Somer, Mehmet Suat; Bateni, Ali; Faculty Member; PhD Student; Department of Chemistry; College of Sciences; Graduate School of Sciences and Engineering
    Nano sized magnesium diboride (MgB2) samples were synthesized using various high-quality nano-B precursor powders. The microscopic defect structures of MgB2 samples were systematically investigated using X-ray powder diffraction, Raman, resistivity measurements and electron paramagnetic resonance spectroscopy. A significant deviation in the critical temperature T-c was observed due to defects and crystal distortion. The symmetry effect of the latter is also reflected on the vibrational modes in the Raman spectra. Scanning electron microscopy analysis demonstrate uniform and ultrafine morphology for the modified MgB2. Defect center in particular Mg vacancies influence the connectivity and the conductivity properties which are crucial for the superconductivity applications.
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    PublicationOpen Access
    Novel approach for synthesis of magnesium borohydride, Mg(BH4)(2)
    (Elsevier, 2012) Scherpe, Stephan; Acar, Selçuk; N/A; Department of Chemistry; Bateni, Ali; Somer, Mehmet Suat; PhD Student; Faculty Member; Department of Chemistry; Graduate School of Sciences and Engineering; College of Sciences; N/A; 178882
    Mg(BH4)(2) is a complex hydride with one of the highest hydrogen contents (similar to 15%) known yet. Several synthesis routes have been reported for it, all based on the metathesis reaction of MgCl2 with NaBH4 performed in a ball-mill or in suitable solvents. In the present study a new approach for synthesis of Mg(BH4)(2) will be presented in which the more reactive MgBr2 is used instead of MgCl2. For this purpose a mixture of MgBr2 and NaBH4 (molar ratio: 1:2 and 1:2.15) was ball-milled for 6, 12 and 18 h, respectively. Mg(BH4)(2) was extracted from the reaction product (Mg(BH4)(2) + NaBr) by Soxhlet with diethylether over a day. The remaining residue after solvent evaporation was dried in vacuum at 150 degrees C for 24 h and 5h at 190 degrees C. The intermediate and final products of the reactions were analyzed using XRD, DTA/TG, Mass and Vibrational Spectroscopy. The XRD diagrams of the mixture after ball milling showed only the characteristic reflections of NaBr and the patterns obtained after solvent extraction was in all cases consistent with beta-Mg(BH4)(2). The additional weak MgBr2 reflections, decreased by increasing the ball milling time from 6 to 18 h. The DTA/TG coupled with MS revealed similar to 11% mass loss when the product was heated up to 600 degrees C. The result of MS detected that the exhaust gas is exclusively H-2. Compared to MgCl2, the use of MgBr2 has two advantages: the reaction time is considerably shorter and the excess of MgBr2 can act as additive lowering the onset temperature for hydrogen release from 290 degrees C - for pure Mg(BH4)(2) - to similar to 220 degrees C. (C) 2012 Published by Elsevier Ltd. Selection and/or peer-review under responsibility of Canadian Hydrogen and Fuel Cell Association.