Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7148
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Article Citation - WoS: 63Citation - Scopus: 64Vacancy Formation and Oxidation Characteristics of Single Layer Tis3(American Chemical Society, 2015) İyikanat, Fadıl; Şahin, Hasan; Senger, Ramazan Tugrul; Peeters, François M.The structural, electronic, and magnetic properties of pristine, defective, and oxidized monolayer TiS3 are investigated using first-principles calculations in the framework of density functional theory. We found that a single layer of TiS3 is a direct band gap semiconductor, and the bonding nature of the crystal is fundamentally different from other transition metal chalcogenides. The negatively charged surfaces of single layer TiS3 makes this crystal a promising material for lubrication applications. The formation energies of possible vacancies, i.e. S, Ti, TiS, and double S, are investigated via total energy optimization calculations. We found that the formation of a single S vacancy was the most likely one among the considered vacancy types. While a single S vacancy results in a nonmagnetic, semiconducting character with an enhanced band gap, other vacancy types induce metallic behavior with spin polarization of 0.3-0.8 μB. The reactivity of pristine and defective TiS3 crystals against oxidation was investigated using conjugate gradient calculations where we considered the interaction with atomic O, O2, and O3. While O2 has the lowest binding energy with 0.05-0.07 eV, O3 forms strong bonds stable even at moderate temperatures. The strong interaction (3.9-4.0 eV) between atomic O and TiS3 results in dissociative adsorption of some O-containing molecules. In addition, the presence of S-vacancies enhances the reactivity of the surface with atomic O, whereas it had a negative effect on the reactivity with O2 and O3 molecules.Article Citation - WoS: 25Citation - Scopus: 26Solution Processable Neutral State Colourless Electrochromic Devices: Effect of the Layer Thickness on the Electrochromic Performance(Royal Society of Chemistry, 2016) Tahtalı, Gürhan; Has, Zeynep; Doyranlı, Ceylan; Varlıklı, Canan; Koyuncu, SermetIn this study, a neutral state colourless electrochromic device fabricated through a solution process is introduced. The device contains indium doped transparent oxide coated glass as the transparent conductive electrode, poly(N-(2-ethylhexyl)carbazol-3,6-diyl) (PCbz) as the anodically colouring material, poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) as the ion storage layer and a lithium perchlorate based conducting gel electrolyte. A maximum optical contrast (ΔT%) of 58% at 800 nm is achieved by optimizing the film thickness of both the organic layers. The device that has layers of 220 nm PCbz and 120 nm PEDOT:PSS thickness revealed a high coloration efficiency (1246 cm2 C-1) and colouring and bleaching response times of 5.6 s and 2.3 s, respectively.Article Citation - WoS: 11Citation - Scopus: 12Hydrothermal Synthesis, Characterization and Magnetic Properties of Navge2o6 and Livge2o6(Elsevier Ltd., 2004) Eanes, Mehtap; Kolis, Joseph W.Supercritical fluids are shown to be an excellent reaction media for the synthesis of novel solid state phases at intermediate temperatures. LiVGe 2O6 and NaVGe2O6 have the common pyroxene structure composed of VO6 linear chains. NaVGe 2O6 crystallizes in the monoclinic space group C2/c with four formula units having cell dimensions a = 9.960(4)Å, b = 8.853(10)Å, c = 5.4861(10)Å, β = 106.403(3)°. The structure was refined until R = 0.0290 and Rw = 0.0370. For LiVGe 2O6 in space group P21/c: a = 9.8508(7)Å, b = 8.754(3)Å, c = 5.3948(13)Å, β = 108(3)°, R = 0.0240 and Rw = 0.0250. The compounds contain edge-shared VO6 octahedral chains and corner-shared GeO4 tetrahedral chains. The presence of these VO6 chains results in spin-Peierls distortion. Structural and physical characterization of the compounds are reported.Article Citation - WoS: 2Citation - Scopus: 2Redetermination of the Crystal Structure of Sodium Trisamarium Digermanate Dihydroxide, Nasm3(geo4)2(oh)2(Walter de Gruyter GmbH, 2002) Eanes, MehtapGe2H2NaO10Sm3, monoclinic, C12/c1 (No. 15), a = 18.323(3)Å, b = 5.2369(8) Å, c = 12.108(2) Å, β= 131.230(2)°, V = 873.8 Å3, Z = 4, R gt(F) = 0.037, wRref(F2) = 0.010, T= 153 K.Article A Two-Dimensional Organic–inorganic Hybrid Compound, Poly[(ethylenediamine)tri-Μ(International Union of Crystallography, 2008) Gün, Özgül; Emirdağ Eanes, Mehtap; Vanderveer, Don; Eanes, MehtapA new organic–inorganic two-dimensional hybrid compound, [CuMoO4(C2H8N2)], has been hydrothermally synthesized at 443 K. The unit cell contains layers composed of CuN2O4 octahedra and MoO4 tetrahedra. Corner-sharing MoO4 and CuN2O4 polyhedra form CuMoO4 bimetallic sites that are joined together through O atoms, forming an edge-sharing Cu2Mo2O4 chain along the c axis. The one-dimensional chains are further linked through bridging O atoms that join the Cu and Mo atoms into respective chains along the b axis, thus establishing layers in the bc plane. The ethylenediamine ligand is coordinated to the Cu atom through its two N atoms and is oriented perpendicularly to the two-dimensional –Cu—O— Mo– layers. The average distance between adjacent layers, as calculated by consideration of the closest and furthest distances between two layers, is 8.7 Å. The oxidation statesof the Mo and Cu atoms of VI and II, respectively, were confirmed by bond-valence sum calculations.