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: 4Citation - Scopus: 3Quantum Monte Carlo Study of Semiconductor Artificial Graphene Nanostructures(AMER PHYSICAL SOC, 2023) Öztarhan, Gökhan; Güçlü, Alev Devrim; Kul, E. Bulut; Okçu, Emre; Guclu, A. D.Semiconductor artificial graphene nanostructures where the Hubbard model parameter U/t can be of the order of 100, provide a highly controllable platform to study strongly correlated quantum many-particle phases. We use accurate variational and diffusion Monte Carlo methods to demonstrate a transition from antiferromagnetic to metallic phases for an experimentally accessible lattice constant a = 50 nm in terms of lattice site radius rho, for finite-sized artificial honeycomb structures nanopatterned on GaAs quantum wells containing up to 114 electrons. By analyzing spin-spin correlation functions for hexagonal flakes with armchair edges and triangular flakes with zigzag edges, we show that edge type, geometry, and charge nonuniformity affect the steepness and the crossover rho value of the phase transition. For triangular structures, the metal-insulator transition is accompanied with a smoother edge polarization transition.Article Citation - WoS: 10Citation - Scopus: 7Assessment of Melt Cleanliness of Secondary 5000 Aluminum Alloy Via Non-Metallic Inclusions Characterization(Springer, 2023) Li, Cong; Dang, Thien; Huang, Jinxian; Huang, Chunfa; Li, Jianguo; Friedrich, Bernd; Gökelma, MertolThe extensive energy consumption of primary aluminum production stimulates increasing need of producing primary-quality alloys with secondary sources, during which process amount of non-metallic inclusions (NMIs) in the alloy must be strictly controlled. In the present study funded by AMAP Open Innovation Research Cluster, NMIs generated during remelting a 5000 Al-Mg alloy was investigated to offer benchmarking characters of NMIs with respect to type, morphology, size, composition, and concentration. Under different remelting conditions NMIs formed in the melt ahead of solidification were concentrated using Porous Disc Filtration Apparatus (PoDFA) and characterized microstructurally and quantitatively. Investigated conditions included heating cycle, organic contaminations, and refractory materials. Results suggested oxide films and cuboid particles as typical oxides with, respectively, different compositions. The amount of formed oxides declined with the increase of heating rate. With respect to aluminum carbide (Al4C3), organic contaminations were confirmed to lead to an increased amount of its formation. The carbon-containing refractory material contributed more significantly than organic contaminations on the formation of Al4C3 at melt temperatures over 760 & DEG;C. Formulas were derived based on trial results to enable translation of NMIs PoDFA value [mm(2)/kg] into their mass fraction [ppm] in the melt.Article Citation - WoS: 8Citation - Scopus: 11Permeation of Pure Gases Through Silica Membranes With Controlled Pore Structures(Elsevier Ltd., 2006) Topuz, Berna; Çiftçioğlu, MuhsinThe superior thermal/chemical/mechanical stability and the ability of ceramic membranes in affecting the transport rates of chemical species through their processing controllable pore structures make them very attractive for many separation problems. Highly selective microporous silica membranes with high fluxes could be prepared by sol–gel dip coating processes [1]. The structure of the thin silica layer mainly depends on the size and the shape of the silicalite polymers and their packing behavior during drying and heat treatment. Design of the pore networks has a great importance to decide the transport properties through the membrane since permeation and the permselectivity are mainly determined by the microstructure of the membrane such as pore size and distribution, porosity as well as the interaction of permeating species with pore walls.