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Article Citation - WoS: 8Citation - Scopus: 9Experimental and Theoretical Investigation of the Mechanical Characteristics of Sillenite Compound: Bi12geo20<(Elsevier Science Sa, 2021) Surucu, Gokhan; Isik, Mehmet; Gencer, Aysenur; Gasanly, NizamiThe present study reports the mechanical and elastic characteristics of Bi12GeO20 (BGO) compound by experimental nanoindentation measurements and density functional theory (DFT) calculations. X-ray diffraction pattern of BGO was plotted and revealed diffraction peaks were associated with Miller indices of cubic crystalline structure with lattice constant of a = 10.304 angstrom. Two- and three-dimensional representations of Young's modulus, linear compressibility, shear modulus and Poisson's ratio were presented according to DFT calculations. The calculated elastic constants pointed out the mechanically stable and anisotropic behavior of the BGO. The hardness and Young's modulus ranges of the BGO calculated from DFT studies were found as 3.7-6.3 GPa and 61.7-98.9 GPa, respectively. Hardness and Young's modulus of BGO single crystal were also obtained by analyzing force-dependent nanoindentation experimental data. It was observed that hardness and Young's modulus decrease with increase of load in the low applied loads and then reaches saturation in the high applied loads. This behavior is known as indentation size effect. True hardness value was determined from proportional specimen resistance model as 4.1 GPa. The force independent region presented the Young's modulus as 114 GPa. (C) 2021 Elsevier B.V. All rights reserved.Article Citation - WoS: 28Citation - Scopus: 29The investigation of electronic, anisotropic elastic and lattice dynamical properties of MAB phase nanolaminated ternary borides: M 2 AlB 2 ( M = Mn , Fe and Co ) under spin effects(Elsevier Science Sa, 2020) Surucu, Gokhan; Yildiz, Bugra; Erkisi, Aytac; Wang, Xiaotian; Surucu, Ozge[No Abstract Available]Article Citation - WoS: 48Citation - Scopus: 50Lattice Dynamical and Thermo-Elastic Properties of M2alb (m = V, Nb, Ta) Max Phase Borides(Elsevier Science Sa, 2020) Surucu, Gokhan; Gencer, Aysenur; Wang, Xiaotian; Surucu, OzgeThe structural, electronic, dynamic, and thermo-elastic properties of M2AlB (X = V, Nb, Ta) MAX phase borides were investigated using first principle calculations as implemented in the Vienna Ab-initio Simulation Package (VASP) with the generalized gradient approximation (GGA). The obtained structural properties and formation energies showed the thermodynamic stability and synthesizability of M2AlB. The electronic band structures were determined and they revealed that these compounds had a metallic character. The dynamic stability of M2AlB compounds were investigated with phonon dispersion curves and these compounds were found to be dynamically stable. The elastic constants were also calculated to determine the mechanical stability and to obtain the polycrystalline properties such as bulk modulus, shear modulus, etc. The thermo-elastic properties (thermal expansion coefficient, heat capacity, entropy, and free energy) were studied in a temperature range in between 0 and 1000 K and a pressure range in between 0 and 30 GPa. In addition, the direction dependent sound wave velocities were studied in three dimensions. Moreover, the minimum thermal conductivities and the diffusion thermal conductivities of these compounds were determined. This work is the processor study for the investigation of the main physical properties of M2AlB (M = V, Nb, Ta) ceramic compounds to date. (C) 2019 Elsevier B.V. All rights reserved.
