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.

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.

A High Sensitivity Isopropanol Vapor Sensor Based on Cr2O3-SnO2 Heterojunction Nanocomposites via Chemical Precipitation Route.

Cr2O3-SnO2 heterojunction nanocomposites were prepared via chemical precipitation method. The prepared samples were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV-Vis diffuse reflectance spectra and Field Emission Electron Microscopy (FESEM). The XRD spectrum confirms the presence of both tetragonal rutile SnO2 and rhombohedral corundum Cr2O3 structure. Further investigation into the gas sensing performances of the prepared Cr2O3-SnO2 nanocomposites exhibited an enhanced sensitivity towards VOPs such as isopropanol, acetone, ethanol and formaldehyde. Especially, isopropanol vapor sensor shows excellent sensitivity at an operating temperature of 100 °C. The highest sensitivity for Cr2O3-SnO2 heterojunction nanocomposites indicate that these materials can be a good candidate for the production of high-performance isopropanol sensors.

Bio-Directed Synthesis of Calcium Oxide (CaO) Nanoparticles Extracted from Limestone Using Honey.

Calcium oxide (CaO) nanoparticles have been synthesized by two step thermal decomposition method under ambient temperature. Structural analysis was carried out by powder X-ray diffraction method and the crystallite size of CaO nanoparticles was calculated using Scherrer formula. Fourier transform infrared spectroscopy (FTIR) analysis has been carried to identify the functional groups present in the synthesized specimen. Optical absorption studies reveal very low absorption in the entire visible region. The surface analysis of the synthesized particles was analysed using scanning electron microscope (SEM).

Optical and spectral studies on pure and europium doped olgite type Na(Sr,Ba)PO4 ceramics.

Europium ion doped olgite type Na(Sr,Ba)PO4 ceramics, a new generation of light emitting bulb, was prepared by a high temperature solid-state reaction method. The synthesized materials were subjected to various characterizations such as X-ray powder diffraction, Scanning electron microscopy and FT-IR spectra measurements. The EPR spectrum of the sample exhibits a well-resolved hyperfine structure of 151Eu2+ and 153Eu2+ isotopes and the g value has been calculated. Fluorescence spectra revealed that europium ions were present in divalent as well as in the trivalent oxidation states. The critical distance for energy transfer between Eu2+ and Eu2+ ion is calculated as 20Å, which is in good agreement with that of experimental data. The FTIR analysis reveals all the vibrations of PO4(3-) ions.

Optical and spectroscopic studies of potassium p-nitrophenolate dihydrate crystal for frequency doubling applications.

Non centrosymmetric potassium p-nitrophenolate dihydrate single crystals have been grown by employing the technique of slow solvent evaporation from aqueous solution by slightly adjusting the pH and growth temperature. The grown crystals have been identified from single crystal XRD analysis, FTIR and FT Raman spectroscopic techniques. The high resolution X-ray diffraction experiments substantiate good quality of the title material. Between 510 and 2000 nm, the material is observed to be nearly transparent allowing it to be explored for potential use in device fabrication. In addition, the photoluminescence spectrum of the grown crystal at room temperature shows a stable broad violet-blue emission around the 383-550 nm wavelengths with the maximum centered at 436 nm. Owing to its excellent non linear figure of merit and strong PL emission, the title crystal can have technological applications in opto-electronic devices.