Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Access Right: Open AccessAuthor: search.filters.author.Şahin, Yüksel

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  • Article
    Citation - WoS: 5
    Citation - Scopus: 5
    Synthesis and Structures of 1,3,2,4,5-Diazatriborolidines
    (Elsevier, 2019) Fırıncı, Erkan; Sevinçek, Resul; Bursalı, Banu; Özgener, Hüseyin; Burgaz, Osman; Şen, Ceren; Şahin, Yüksel
    The derivatives of diazatriborolidine are a class of 5-membered heterocyclic compounds containing a ring with two nitrogen atoms and three boron atoms. The 1,3,2,4,5-diazatriborolidine derivatives were synthesized from 1,2-bis(N-lithium-arylamino) diborane(4) and dichloro-dimethylaminoborane with high yield. The structures of these new derivatives were determined using nuclear magnetic resonance (NMR) spectroscopy. The molecular structures of 3a, 3b, 3d, 4b and 4c were determined using single-crystal X-ray diffraction. Their structural features were discussed and compared with similar diazatriborolidines. In addition, the enthalpy of formation of B and N atoms containing five membered heterocycles were calculated theoretically for the first time. Also, an easy and efficient synthesis route has been reported for preparation of 1,3,2,4,5-diazatriborolidine derivatives.
  • Article
    Citation - WoS: 46
    Citation - Scopus: 50
    Investigation of Europium Concentration Dependence on the Luminescent Properties of Borogermanate Glasses
    (Elsevier Ltd., 2017) Gökçe, Melis; Şentürk, Ufuk; Uslu, Deniz K.; Burgaz, Gözde; Şahin, Yüksel; Gökçe, Aytaç Gürhan
    In order to elucidate the effect of europium content on the optical and luminescent properties of borogermanate glasses, a series of Eu3+ doped 30B2O3-40GeO2-(30-x)Gd2O3 glasses with various doping levels (x=1–9 mol%) have been synthesized and studied with transmission, absorption, photoluminescence and decay time measurements. The transmission spectra proved that the title glasses maintained a high transparency about 80% in the 440 to 900 nm region. Based on the absorption spectra, the optical band gaps obtained from Tauc's plot can be narrowed by increasing content of Eu3+. From the photoluminescence spectra, the strongest red emission has been observed from the 5D0→7F2 level of Eu3+ ions in borogermanate glasses. The strongest emission and excitation intensities of Eu3+ ions are at the doping level of x=7 mol% and then these intensities decrease due to concentration quenching. The red to orange ratio (R/O) of 5D0→7F2 to 5D0→7F1 transitions has been investigated to predict the local environment of Eu3+ ions. Judd-Ofelt (J-O) analyses have been performed from the emission spectra. The values of R/O and Ω2 present an increase with increasing doping level, indicating the lower symmetric environment for Eu3+ ions and higher covalency for Eu-O bond. The emission efficiency calculated from J-O theory is 75% at x=2 mol%. The decay time curves of 6P7/2→8S7/2 transition of Gd3+ ions and 5D0–7F2 transition of Eu3+ ions confirm the energy transfer from Gd3+ to Eu3+ ions.