WoS İndeksli Yayınlar Koleksiyonu / WoS Indexed Publications Collection
Permanent URI for this collectionhttps://hdl.handle.net/11147/7150
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Article Citation - WoS: 19Citation - Scopus: 21Fundamental Mechanisms Responsible for the Temperature Coefficient of Resonant Frequency in Microwave Dielectric Ceramics(John Wiley and Sons Inc., 2017) Zhang, Shengke; Şahin, Hasan; Torun, Engin; Peeters, François M.; Martien, Dinesh; DaPron, Tyler; Dilley, Neil; Newman, NathanThe temperature coefficient of resonant frequency (τf) of a microwave resonator is determined by three materials parameters according to the following equation: τf=−(½ τε + ½ τμ + αL), where αL, τε, and τμ are defined as the linear temperature coefficients of the lattice constant, dielectric constant, and magnetic permeability, respectively. We have experimentally determined each of these parameters for Ba(Zn1/3Ta2/3)O3, 0.8 at.% Ni-doped Ba(Zn1/3Ta2/3)O3, and Ba(Ni1/3Ta2/3)O3 ceramics. These results, in combination with density functional theory calculations, have allowed us to develop a much improved understanding of the fundamental physical mechanisms responsible for the temperature coefficient of resonant frequency, τf.Article Citation - WoS: 15Citation - Scopus: 18Computing Optical Properties of Ultra-Thin Crystals(John Wiley and Sons Inc., 2016) Şahin, Hasan; Torun, Engin; Bacaksız, Cihan; Horzum, Şeyda; Kang, J.; Senger, Ramazan Tuğrul; Peeters, François M.An overview is given of recent advances in experimental and theoretical understanding of optical properties of ultra-thin crystal structures (graphene, phosphorene, silicene, MoS2 , MoSe2 , WS2 , WSe2 , h-AlN, h-BN, fluorographene, and graphane). Ultra-thin crystals are atomically thick-layered crystals that have unique properties which differ from their 3D counterpart. Because of the difficulties in the synthesis of few-atom-thick crystal structures, which are thought to be the main building blocks of future nanotechnology, reliable theoretical predictions of their electronic, vibrational, and optical properties are of great importance. Recent studies revealed the reliable predictive power of existing theoretical approaches based on density functional theory.Article Citation - WoS: 14Citation - Scopus: 14Quantum-Transport Characteristics of a P–n Junction on Single-Layer Tis3(John Wiley and Sons Inc., 2016) İyikanat, Fadıl; Senger, Ramazan Tuğrul; Peeters, François M.; Şahin, HasanBy using density functional theory and non-equilibrium Green′s function-based methods, we investigated the electronic and transport properties of a TiS3 monolayer p–n junction. We constructed a lateral p–n junction on a TiS3 monolayer using Li and F adatoms. An applied bias voltage caused significant variability in the electronic and transport properties of the TiS3 p–n junction. In addition, the spin-dependent current–voltage characteristics of the constructed TiS3 p–n junction were analyzed. Important device characteristics were found, such as negative differential resistance and rectifying diode behaviors for spin-polarized currents in the TiS3 p–n junction. These prominent conduction properties of the TiS3 p–n junction offer remarkable opportunities for the design of nanoelectronic devices based on a recently synthesized single-layered material.Article Citation - WoS: 14Citation - Scopus: 14Formation and Diffusion Characteristics of Pt Clusters on Graphene, 1h-Mos2 and 1t-Tas2(John Wiley and Sons Inc., 2014) Özaydın, H. Duygu; Şahin, Hasan; Şenger, Ramazan Tuğrul; Peeters, François M.Many experiments have revealed that the surfaces of graphene and graphene-like structures can play an active role as a host surface for clusterization of transition metal atoms. Motivated by these observations, we investigate theoretically the adsorption, diffusion and magnetic properties of Pt clusters on three different two-dimensional atomic crystals using first principles density functional theory. We found that monolayers of graphene, molybdenum disulfide (1H-MoS2) and tantalum disulfide (1T-TaS2) provide different nucleation characteristics for Pt cluster formation. At low temperatures, while the bridge site is the most favorable site where the growth of a Pt cluster starts on graphene, top-Mo and top-Ta sites are preferred on 1H-MoS2 and 1T-TaS2, respectively. Ground state structures and magnetic properties of Ptn clusters (n = 2,3,4) on three different monolayer crystal structures are obtained. We found that the formation of Pt2 dimer and a triangle-shaped Pt3 cluster perpendicular to the surface are favored over the three different surfaces. While bent rhombus shaped Pt4 is formed on graphene, the formation of tetrahedral shaped clusters are more favorable on 1H-MoS2 and 1T-TaS2. Our study of the formation of Ptn clusters on three different monolayers provides a gateway for further exploration of nanocluster formations on various surfaces.