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: 20Citation - Scopus: 21Monitoring the Effect of Asymmetrical Vertical Strain on Janus Single Layers of Mosse Via Vibrational Spectrum(American Institute of Physics, 2018) Kandemir, Ali; Peeters, François M.; Şahin, HasanUsing first principles calculations, we study the structural and phononic properties of the recently synthesized Janus type single layers of molybdenum dichalcogenides. The Janus MoSSe single layer possesses 2H crystal structure with two different chalcogenide sides that lead to out-of-plane anisotropy. By virtue of the asymmetric structure of the ultra-thin Janus type crystal, we induced the out-of-plane anisotropy to show the distinctive vertical pressure effect on the vibrational properties of the Janus material. It is proposed that for the corresponding Raman active optical mode of the Janus structure, the phase modulation and the magnitude ratio of the strained atom and its first neighbor atom adjust the distinctive change in the eigen-frequencies and Raman activity. Moreover, a strong variation in the Raman activity of the Janus structure is obtained under bivertical and univertical strains. Not only eigen-frequency shifts but also Raman activities of the optical modes of the Janus structure exhibit distinguishable features. This study reveals that the vertical anisotropic feature of the Janus structure under Raman measurement allows us to distinguish which side of the Janus crystal interacts with the externals (substrate, functional adlayers, or dopants).Article Citation - WoS: 110Citation - Scopus: 109Structural, Electronic and Phononic Properties of Ptse2: From Monolayer To Bulk(IOP Publishing Ltd., 2018) Kandemir, Ali; Akbalı, Barış; Kahraman, Z.; Badalov, S. V.; Özcan, Mehmet; İyikanat, Fadıl; Şahin, HasanThe layer dependent structural, electronic and vibrational properties of the 1T phase of two dimensional (2D) platinum diselenide are investigated by means of state-of-the-art first-principles calculations. The main findings of the study are: (i) monolayer platinum diselenide has a dynamically stable 2D octahedral structure with 1.66 eV indirect band gap, (ii) the semiconducting nature of 1T-PtSe2 monolayers remains unaffected even at high biaxial strains, (iii) top-to-top (AA) arrangement is found to be energetically the most favorable stacking of 1T-PtSe2 layers, (iv) the lattice constant (layer-layer distance) increases (decreases) with increasing number of layers, (v) while monolayer and bilayer 1T-PtSe2 are indirect semiconductors, bulk and few-layered 1T-PtSe2 are metals, (vi) Raman intensity and peak positions of the A1g and Eg modes are found to be highly dependent on the layer thickness of the material, hence; the number of layers of the material can be determined via Raman measurements.Article Citation - WoS: 130Citation - Scopus: 135Thermal Transport Properties of Mos2 and Mose2 Monolayers(IOP Publishing Ltd., 2016) Kandemir, Ali; Yapıcıoğlu, Haluk; Kınacı, Alper; Çalın, Tahir; Sevik, CemThe isolation of single- to few-layer transition metal dichalcogenides opens new directions in the application of two-dimensional materials to nanoelectronics. The characterization of thermal transport in these new low-dimensional materials is needed for their efficient implementation, either for general overheating issues or specific applications in thermoelectric devices. In this study, the lattice thermal conductivities of single-layer MoS2 and MoSe2 are evaluated using classical molecular dynamics methods. The interactions between atoms are defined by Stillinger-Weber-type empirical potentials that are developed to represent the structural, mechanical, and vibrational properties of the given materials. In the parameterization of the potentials, a stochastic optimization algorithm, namely particle swarm optimization, is utilized. The final parameter sets produce quite consistent results with density functional theory in terms of lattice parameters, bond distances, elastic constants, and vibrational properties of both single-layer MoS2 and MoSe2. The predicted thermal properties of both materials are in very good agreement with earlier first-principles calculations. The discrepancies between the calculations and experimental measurements are most probably caused by the pristine nature of the structures in our simulations.Article Citation - WoS: 2Citation - Scopus: 3The Amido and Bisalkoxo-Complexes of [tri(3,5-Dimethylpyrazolyl)borato]molydenum Nitrosyl(TÜBİTAK, 1998) Topaloğlu, IşılIn this study, the amido nitrosyl molybdenum complex, [Mo{HM(3,5-Me2C3HN2)3}(NO)Cl(NH 2)], was prepared. This compound reacts with alocohols, yielding the bisalkoxo complexes, [Mo{HM(3,5-Me2C3HN2)3}(NO)(OR) 2] (R = Me, Et, Prn, Bun). The new complexes were analyzed by IR and 1H-NMR spectroscopy.