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Evaluating the Mass Sensing Characteristics of SWCNC
Published in Satya Bir Singh, Prabhat Ranjan, Alexander V. Vakhrushev, A. K. Haghi, Mechatronic Systems Design and Solid Materials, 2021
Umang B. Jani, Bhavik A. Ardeshana, Ajay M. Patel, Anand Y. Joshi
Authors have evaluated frequencies for deferent types of defects and there location of the defect on the surface of SWCNC as shown in Figure 4.12 such as vacancy defect and Stone-Wales defect. For producing the vacancy defect author removed one carbon atom at a particular location such as the top, middle, and bottom of the cone and associated three C-C bonds. For this defective SWCNC mass attached has been kept constant 10–16 to check only for defect variations. Defects recreated on length of 20Å and on four disclination angle including 60°, 120°, 180°, and 240° which are shown in Figures 4.12 and 4.13.
Nanoscale Resistive Random Access Memory
Published in Santosh K. Kurinec, Krzysztof Iniewski, Nanoscale Semiconductor Memories, 2017
For HRS state, Ielmini et al. have found the impact of oxygen vacancy/defect concentration on activation energy [64]. A gradual change can be seen in Figure 13.19. The role of the oxygen vacancies is similar to dopants. Therefore, in LRS, large local density of oxygen vacancies causes metal–insulator transition in a similar manner with the degenerately doped semiconductors.
The Structure of Solids
Published in Joseph Datsko, Materials Selection for Design and Manufacturing, 2020
Two additional types of atom displacement defects, which are not present in metallic bonded crystals, occur in ionic crystals. A vacancy defect in an ionic crystal that is associated with a displaced pair, one cation and one anion, is called a Scholtky defect. A Frenkel defect occurs when a small cation moves from a lattice point, leaving a vacancy, and occupies an interstitial site.
Assessing the performance of Al- and Ga-doped BNNTs for sensing and delivering Cytarabine and Gemcitabine anticancer drugs: a M06-2X study
Published in Molecular Physics, 2023
Hossein Roohi, Mino Rouhi, Ahmad Facehi
The optimized structures of Al – and Ga-doped BNNTs are illustrated in Figure 1. As the atomic radius of Al and Ga is larger than that of B, these dopant atoms are positioned outside the surface of the nanotube and exhibit sp3 hybridization. This preferential sp3 hybridization causes the dopant atoms to move outward from the tube surface, creating an active site for interaction with molecules. The sp3 hybridization also leads to elongation of the B-N bonds closest to the Al or Ga atoms. Due to the larger covalent radius of Ga compared to Al, the average value of the Ga-N bond in Ga-doped BNNTs (1.816 Å) is greater than that of Al-doped BNNTs (1.762 Å). The formation energy (Ef) of the Al – or Ga-doped BNNTs can be calculated using the following equation: where Epristine and Edoped represent the energy of pristine and doped BNNTs, respectively, and EB and EM are the energy of a B and an Al or Ga atoms. The calculated Ef of Al-BNNT is 2.85 eV which is much smaller than the Ef of Ga-BNNT (5.6 eV), indicating that the Al atom can be more easily incorporated into a B-vacancy defect of BNNT.
Effect of doping and vacancy defect on the sensitivity of stanene toward HCN
Published in Molecular Physics, 2022
Shumin Yan, Qingxiao Zhou, Weiwei Ju, Xiangyang Li
Figure 1(a) and (b) show the optimised structures of pristine stanene and vacancy-defected stanene. The vacancy-defect stanene is obtained by removing a tin atom from pristine stanene. The pristine and vacancy-defect stanene atoms used in this study have been referred to as Sn and VSn, respectively. The geometric variation caused by void defects is similar to that observed in other two-dimensional materials, such as graphene, silicene and arsenene [21,36,41]. The warp height of the atoms at the defects changed to some extent. The bond length of pristine stanene is 2.843 Å. Through the introduction of vacancy defects, the distances between atoms Sn1 to Sn2, Sn2 to Sn3 and Sn3 to Sn1 are changed to 3.638, 3.653 and 3.634 Å, respectively. To further study the influence of vacancy on stanene, the band structures are determined (Figure 2a and b). Similar to graphene, stanene is a zero-band gap semiconductor whose Dirac point is the K point; this result is consistent with previous reports [33,34,42] and proves that our calculation method is reliable. Figure 1(d) shows that the presence of a vacancy causes the band gap to open by roughly 0.087 eV at the Dirac point.
Si-doped C3N monolayers as efficient single-atom catalysts for the reduction of N2O: a computational study
Published in Molecular Physics, 2020
Mehdi D. Esrafili, Safa Heydari
We performed the spin-unrestricted DFT calculations with the Dmol3 [39,40]. The geometry optimisations and subsequent frequency calculations were carried out by the Perdew–Burke–Ernzerhof functional [41], by employing a double numerical plus polarisation basis set. To correct van der Waals effects, the DFT-D2 scheme of Grimme was applied [42,43]. The electronic self-consistent field (SCF) tolerance was set to 10−6 Ha. The real-space global orbital cutoff was set to 4.6 Å. The convergence criteria for force and displacement were 1.0 × 10−3 Ha/Å and 5.0 × 10−3 Å as threshold, respectively. The pristine C3N nanosheet was modelled by using a hexagonal 5 × 5 supercell containing 54 carbon and 18 nitrogen atoms. To construct the Si-C3N nanosheets, a C- or N-vacancy defect was first created and then a single Si atom was deposited on the vacancy site. To hinder the interaction between two adjacent sheets, a vacuum space of 20 Å was adopted. The Brillouin-zone integration was performed within the Monkhorst–Pack scheme using a uniform 3 × 3 × 1 for the geometry optimisations. A denser k-point grid was set to 10 × 10 × 1 for the partial density of state (PDOS) analysis. The transition state structures were computed by the linear synchronous transit/quadratic synchronous transit method.