P. Annie Vinosha

Hydrothermal synthesis of zinc stannate nanoparticles for antibacterial applications

Abstract A facile and economical hydrothermal method was used to synthesise Zn2SnO4 nanoparticles with cubic spinel structure. The crystallography and optical properties of the as-synthesised nanoparticles were studied using X-ray diffraction (XRD) and UV–visible spectroscopy (UV–vis). The morphology of the nanoparticles was observed using field emission scanning electron microscopy (FESEM). The synergistic antibacterial effect of Zn2SnO4 nanoparticles against Gram-positive and Gram-negative pathogenic bacteria was investigated. These results indicate that the Zn2SnO4 nanoparticles have potent antibacterial activity against both Gram-positive and Gram-negative bacteria and can be used as a bactericidal agent to prevent and control the spread and persistence of infectious diseases.

Investigation on the Magnetically Separable Zn Substituted CoFe2O4 Nanoparticles with Enhanced Photo-Fenton Degradation.

We report the influence of Co1-xZnxFe2O4 nanoferrites for the photodegradation of organic pollutant present in the aqueous solution. A series of Co1-xZnxFe2O4 (x = 0.01, 0.03, 0.05 and 0.10) nanoferrites have been synthesized via a facile and economically viable coprecipitation technique and investigated the effect of zinc dopant in their structural, optical, electrical and magnetic properties. X-ray diffraction and Fourier Transform Infrared spectral studies reveal the spinel phase formation of the as-synthesized nanoferrites. Photoluminescence and UV-visible spectral studies show the bandgap of nanoferrites increase from 2.47-2.67 eV and exhibited a blue shift in the band edge emission with respect to increase in Zn content. Phase transition of the samples from weak ferromagnetic to superparamagnetic nature has been observed by Vibrating Sample Magnetometer at room temperature. Furthermore, the Co1-xZnxFe2O4 was assessed for the degradation of Methylene Blue (MB) dye and the sample with Co1-0.10Zn0.10Fe2O4 showed better photocatalytic degradability of organic MB due to its enhanced adsorption in the visible region and the existence of lower concentration charge-carriers.

Study of Structural, Optical, Dielectric and Magnetic Properties of Zinc Ferrite Synthesized by Co-Precipitation

Spinel zinc ferrite (ZnFe2O4) nanoparticles have engrossed immense attention due to its unusual amalgamation of its properties especially the magnetic properties and these properties are catered as fitting candidates in the field of electronics. Nanostructured spinel zinc ferrite particles were synthesized using scalable co-precipitation technique. The morphology, particle size and reaction pace of the nanoparticles (NPs) were fine tuned by eco-friendly technique. These NPs were characterized by UV-Visible spectroscopy (UV-Vis), photoluminescence (PL), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Transmission electron microscopy (TEM), vibrating sample magnetometer ((VSM) and Dielectric studies. The required profiles were confirmed by XRD and FTIR spectra, UV-Vis, PL spectral studies. Further these measurements divulge the significance of optical properties and the spectral parameters are used to appraise the optical constants required for fabrication. Transmission electron microscopy eventually discloses the morphological analysis of the synthesized ZnFe2O4 nanoparticle as 15 nm within the scaling limitations. Using, VSM, the magnetic behaviour of the material have been determined as a function of magnetic field at ambient temperature; the magnetic measurements well-establishes the magnetic property and disclosed to have weak ferromagnetic behaviour as the crystallite size decreases. The A.C. conductivity measurements and dielectric studies were done as a functional dependence of frequency and temperature on synthesized nanoparticles.

Effect of Lanthanum Substitution on Magnetic and Structural Properties of Nickel Ferrite

Inverse spinel ferrites have demanded substantial attention in the recent past owing to their diverse technological deeds by conquering admirably with its surface, finite size effects and optical properties which has its proficient applications in photocatalytic degradation, magnetic resonance imaging and sensors etc. The substituted La3+ ions delay the development of grain growth of the materials in a meticulous manner compared with that of the pure Ni ferrites. We tale development of magnetic features in La3+ substituted Ni nano-ferrites synthesized by co-precipitation technique and then analyzed from the structural and magnetic perspectives. A credible and thriftily doable co-precipitation method has been the spotlight of forethought in recent decades to synthesize these ferrite nanoparticles. Enviable inverse spinel phase has been observed, as it is essential to modify and optimise its micro structural and magnetic features. The phase formation and significant properties of Ni1-xLaxFe2O4 ferrites were investigated using XRD, FTIR, TEM, UV-visible, VSM and FT-Raman techniques. The crystallite size of the as-synthesized nanoparticles were observed after the substitution of La3+ content in the range of 8 to 15 nm. As the dopant concentration increases the crytallite size increases and other changes in crystallographic parameters, as well as the cation distribution also observed. The TEM micrograph clearly reveals the cubic and the notable polycrystalline nature. The FTIR measurements carried out in the range of 400-4000 cm-1 elucidates the occurrence of functional groups. The UV-visible spectrum analysis reveals the optical property of as-synthesized nanoparticle and hence their band gap was found using Kubelka-Munk plot. The magnetic parameters were studied by vibrating sample magnetometer and the saturation magnetization of the ferrites at the room temperature decreases with the reduction in size.

Investigations on Hydrothermally Prepared Tin Mono-Sulphide Nanoparticles

Optically active, tin mono-sulphide (SnS) nanoparticles, having generic name herzenbergite, being one of the narrow band gap IV–VI semiconductors, geared up recently the attention of material scientists for its applications in photovoltaics, near-infrared detectors, and biomedical applications where strong scientific information on infrared absorption is required. Among the class of chalcopyrite semiconductors, SnS is a relatively inexpensive and non-toxic material with the nature of resource abundance for solar cell applications, having a bulk direct band gap of 1.3 eV and indirect bandgap of 1.1 eV, possessing high figure of merit such as optimum optical band gap, high optical absorption coefficient for photons and high photoelectric conversion efficiency of up to 25%. In the present work, nanostructured SnS particles of 11.75 nm were synthesized by means of a cinch hydrothermal reaction using the reagents tin chloride pentahydrate and thiourea at 200°C. The crystallinity, purity, morphology, and structural featuresof as-prepared nanoparticles were characterized by Powder X-ray Diffraction (XRD), Transmission Electron Microscope (TEM), UV-visible spectroscopy (Uv-vis), Photoluminescence spectroscopy (PL) and Fourier Transform Infra-red Spectroscopy (FTIR). XRD measurements reveal the formation of well-crystallized orthorhombic tin mono-sulphide nanoparticles which may be considered as a distorted NaCl structure. TEM observations demonstrate the morphology of the nanoparticles. The FTIR examination confirmed the existence of the vital functional groups. Absorption spectrum showed that the nanoparticles have an extensive absorption array. The optical properties determined by Uv-vis and PL measurements show that the prepared SnS nanoparticles will be an ideal candidate for photovoltaic applications.