In this study, Ni1−xZnxFe2O4 (x = 0, 0.25, and 0.5) nanoparticles were successfully synthesized via microwave-assisted combustion method and characterized by XRD, FTIR, and SEM–EDAX. XRD results enunciate that the nanoparticle crystallizes in cubic spinel structure with an average crystallite size (40.2, 37.2, 35.1 nm), and also, the lattice strain, specific surface area, X-ray density were evaluated. The morphology and chemical compositions of Ni, Zn, Fe, and O elements were confirmed by the SEM–EDAX studies. For all the samples, vibrational stretching modes of Mtetra–O site (597 (S1), 593 (S2), 583 (S3) cm−1) and Moctra–O site (416 (S1), 421 (S2), 422 (S3) cm−1) were related to the distribution of the cation Ni2+/Zn2+ and Fe3+ ions among the octahedral and tetrahedral sites. From the UV–Vis–DRS spectra, the optical energy band gap has been estimated to be 1.75–2.01 eV. The dielectric constant and loss were measured by varying the applied frequency (50 Hz to 200 kHz) at room temperature. The electronic polarizability (α) was calculated using Penn analysis, Clausius–Mossotti equation, and energy band gap value. Third-order nonlinear optical parameters such as the nonlinear absorption coefficients (10−5 cm/W), refractive index (10−9 cm2/W) and the third-order nonlinear susceptibilities (10−6 esu) were determined by Z-scan technique. The antibacterial studies were tested against Bacillus cereus, Staphylococcus aureus, Shigalla flexneri and Klebsiella pneumonia bacterial strains. The existing results point out that the synthesized Ni/Zn/Fe2O4 nanoparticles are possible candidates for photonic devices, optical switches, optical limiting and also for pharmaceutical applications.

Investigations on solid-state parameters of third-order nonlinear optical Ni1−xZnxFe2O4 nanoparticles synthesized by microwave-assisted combustion method

The synthesis and crystal structure of rhodamine 590 acid phthalate (RhAP) have been reported. This novel solid-state rhodamine derivative not only has a longer fluorescence lifetime compared to rhodamine solid-state matrixes where emission is quenched but also possesses strong nonlinear optical characteristics. The static and dynamic first- and second-order hyperpolarizabilities were calculated using the time-dependent density functional theory at the B3LYP/6-31+G∗ level. The computed static values of β and γof RhAP by the X-ray diffraction (XRD) structure were 31.9 × 10-30 and 199.0 × 10-36 esu, respectively. These values were about 62 times larger than the corresponding values in urea, an already well-known nonlinear optical material. The second-order hyperpolarizability of the compound was determined experimentally by measuring the two-photon absorption cross section using intensity-modulated light fields. The reported compound, excitable at near-infrared, exhibited frequency upconversion with the two-photon absorption coefficient enhanced by two orders of magnitude compared to that of the dye solution. Hosting the dye in the solid, at high concentrations, exploits the nonlinearity of the dye itself as well as results in significant excitonic effects including formation of broad exciton band and superradiance. (Less)

New nonlinear optical crystal of rhodamine 590 acid phthalate

An enhanced method of synthesizing silver nanoparticles (AgNPs) is adopted herein using the aqueous extract of Decalepis hamiltonii root as both reducing and capping agents. In the recent years, metal nanoparticles have been actively synthesized using green route which is considered as an efficient, inexpensive and eco-friendly method. The generation of AgNPs was first observed from the UV–visible spectroscopy. The XRD analysis confirms the FCC structure with an average crystal size of 22 nm which is calculated using Scherrer’s formula. The functional group responsible for the reduction of AgNPs is identified from the FTIR analysis. Transmission electron microscopy (TEM) showed the formation of silver nanoparticles of size ranging from 5 to 20 nm with few agglomerations. The antibacterial studies were carried out against the Escherichia coli and Staphylococcus aureus using minimum inhibitory concentration (MIC) technique. The third-order nonlinear optical properties of AgNPs were measured by the Z-scan technique. The negative nonlinearity observed was utilized for the study of optical limiting behavior.

J. Ruhena Parveen

Papers

Green synthesis, characterization of silver nanoparticles and their study on antibacterial activity and optical limiting behavior