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Crystalline Structure of Different Semiconductors
Published in Jyoti Prasad Banerjee, Suranjana Banerjee, Physics of Semiconductors and Nanostructures, 2019
Jyoti Prasad Banerjee, Suranjana Banerjee
A two-dimensional Bravais lattice can be formed in five distinct ways of arrangement of lattice points, as shown in Figure 1.13 Among these, the oblique lattice is the most general type that remains invariant only under twofold and one fold rotation of π and 2π, respectively, about any lattice point. In case of a general oblique lattice shown in Figure 1.13a, the lattice translational vectors a→, b→ and the angle between them, α can be chosen arbitrarily, since no special relationship exists among them. When a→, b→ and α are related in some special way or α has some particular value, four special lattices are formed, as shown in Figure 1.13b–e, respectively. These special lattices of oblique type are invariant under threefold, fourfold, or sixfold rotation axis or under mirror refraction.
Mononuclear photoluminescent salicylaldimato copper(II) complex: synthesis, characterization, mesomorphic investigation and DFT study
Published in Soft Materials, 2023
Harun A. R. Pramanik, Bandashisha Kharpan, Barnali Bhattacharya, Chira R. Bhattacharjee, Pradip C. Paul, Utpal Sarkar, S. Krishna Prasad, D. S. Shankar Rao
The symmetry of the mesophase for the Copper complex was examined on the basis of temperature-dependent X-ray diffraction analysis (Table 2) and was recorded as intensity versus 2θ profile at T = 90°C (Fig. 6). A set of several reflections were observed in the XRD pattern that could be better fitted to a two-dimensional oblique lattice with lattice parameters a = 40.63 Å, b = 39.18 Å and an angle γ between the two directions of about 79.5°C. These data indicate the formation of a tilted columnar structure and the resulting columns organize into an oblique lattice (Fig. 7). In the oblique columnar (Colo) phase, the columnar axis is perpendicular to the normal of the lattice plane and the projection of the hard columnar cores onto the lattice plane leads to a two-dimensional lattice parallelogram. This pattern has rarely been observed in the columnar phase[55–58] because stronger core–core interactions are needed for tilted arrangement of the column. For the columnar oblique lattice, the unit cell volume was calculated from Vcell = ab(sinγ)heff. Effective height (heff) of the molecule is 4.5 Å as obtained from the position of the diffuse wide angle scattering in the XRD pattern. Vcell = 7041.7 Å3, So = ab sinγ = 1564.82 Å2.