In this work, pure and Alumina doped cobalt ferrite nanoparticles CoFe 2−x Al x O 4 (for x = 0.44) have been synthesized by the sol gel method. The influence of alumina doping on the morphological and mechanical properties of CoFe 2 O 4 nano-particles were investigated by means of X-ray powder diffraction (XRD) and rietveld analysis. XRD analysis confirmed that the single phase formation of pure nano particles with the expected cubic inverse spinel structure with Fd3m space group and without any impurity phase. Alumina doping were led to a decrease in the crystallite size, lattice parameter, elastic constants and magnitude of moduli. It is explained on the basis of the replacement of Fe ions with half-filled d-shell (3d 5 ) and larger radius by Al 3+ ions with a completely filled shell (2p 6 ) and smaller radius.

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Synthesis and complex theoretical and experimental studies of Co/TiO 2 anatase have been reported. The preparation of Co/TiO 2 was carried out by sol-gel method. Distribution of cations among the two tetrahedral and octahedral sites was estimated by analyzing the powder X-ray diffraction patterns by employing Rietveld refinement technique, and the results revealed the existence of tetragonal structure. Band structure and density of states calculations were performed using the first-principles methods. The structural and electronic properties of Co/TiO 2 were calculated in the general gradient approximation (GGA). An additional comparison with pure TiO 2 anatase allowed us to clarify cobalt doping effect on the electronic structure and the band gap. The band gap of Co/TiO 2 was decreased by broadening the valence band as a result of the overlap among Co 3d, Ti 3d, and O 2p states, which made it respond better to visible and solar light.

In this study, we present a systematic study of linear and nonlinear optical properties of Para Red with the aim of Z-scan technique and quantum mechanical calculations. The Z-scan experiments were performed using a 532 nm Nd: YAG (SHG) CW laser beam. Para Red exhibited a strong nonlinear refractive index, nonlinear absorption coefficient and third-order nonlinear susceptibility 3.487 × 10−6 cm2/W, 2.341 × 10−1cm/W and 2.157 × 10−4 esu, respectively. Also, quantum chemical analysis was used for the calculation of the dipole moment μ, dipole polarizability α, anisotropy of polarizability Δα and molecular hyperpolarizabilities (β,γ). The results revealed that Para Red has large first and second hyperpolarizabilities. However, from the obtained results, it was found that Para Red can be a promising material for applications in the development of non-linear optical materials.

In this study, 4-(4,5-Diphenyl-1H-imidazole-2-yl) phenol is successfully synthesized, and its nonlinear optical properties (NLO) are investigated both experimentally and theoretically. Theoretical investigations have been done by using TDDFT and B3LYP functional with usual 6-31+G(d,p) basis set. The results of HOMO-LUMO and NBO analysis show the low energy gap, high total dipole moment, and hyperpolarizabilities (β, γ) as well as the presence of dipolar excited states with relatively significant dipole-moment changes which are linked to the nonlinearity. The z-scan technique confirmed the NLO properties of title compound. The nonlinear absorption coefficient, refractive index, and third-order susceptibility were found to be 4.044 × 10−1 cmW−1, 2.89 × 10−6 cm2W−1 and 2.2627 × 10−6 esu, respectively. The negative sign of n2 indicated the occurrence of self-defocusing nonlinearity. The results show that the title compound can been used as potential NLO material.