K. P. Priyanka

Effect of electron beam irradiation on the structure and optical properties of nickel oxide nanocubes

This work reports the effect of electron beam (EB) irradiation on the structure and optical properties of nanocrystalline nickel oxide (NiO) cubes. NiO nanocubes were synthesized by the chemical precipitation method. The characterization was carried out by employing analytical techniques like X-ray diffraction, transmission electron microscopy, UV–visible and photoluminescence (PL) spectroscopy. The present investigation found that non-stoichiometry, defects and particle size variation caused by EB irradiation have a great influence on optical band gap, blue shift and band modification of absorption and PL spectra. Moreover, EB irradiation can result enhanced optical absorption performance and photo-activity in NiO nanocubes for optoelectronics and photo-catalytic applications. The study of International Commission on Illumination chromaticity diagram indicates that NiO can be developed as a suitable phosphor material for the application in near ultraviolet excited colour LEDs.

Effect of Electron Beam Irradiation on Optical Properties of Manganese Tungstate Nanoparticles

Manganese tungstate (MnWO4) nanoparticles were synthesized at room temperature by chemical precipitation method. The effect of high energy electron beam (EB) irradiation on the optical properties of MnWO4 nanoparticles was investigated. The absorption spectra, photoluminescence intensity, and Raman bands of the irradiated samples were modified, which has been attributed to defects and particle size variation. The present investigation found that the beam irradiation is a new and efficient method to enhance the optical absorption performance and photoactivity of MnWO4 nanoparticles.

Influence of electron beam irradiation on structural and optical properties of α-Ag2WO4 nanoparticles

The influence of 8MeV electron beam irradiation on the structural and optical properties of silver tungstate (α-Ag2WO4) nanoparticles synthesized by chemical precipitation method was investigated. The dose dependent effect of electron irradiation was investigated by various characterization techniques such as, X-ray diffraction, scanning electron microscopy, UV-vis absorption spectroscopy, photoluminescence and Raman spectroscopy. Systematic studies confirm that electron beam irradiation induces non-stoichiometry, defects and particle size variation on α-Ag2WO4, which in turn results changes in optical band gap, photoluminescence spectra and Raman bands.

Cerium doped nanotitania—extended spectral response for enhanced photocatalysis

Titania nanoparticles were synthesized using the sol-gel method. Nano-sized Ce particles were doped into nanotitania using the metal sol method. As-synthesized TiO2 and Ce doped TiO2 nanoparticles were characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible spectroscopy and photoluminescence (PL) spectroscopy. Photocatalytic degradation of methylene blue by undoped and ceria-doped titania was investigated under visible light. The dye degradation capabilities of nano-sized Ce-TiO2 catalysts were found to be superior to undoped TiO2 nanoparticles. The higher photoactivity of TiO2 can be ascribed to the effect of Ce dopants on band gap narrowing, and acting as electron traps on the Ce-TiO2 surface. Dye degradation studies show that nanotitania doped with Ce is suitable for higher photocatalytic activity under visible light.

Silver Tungstate Nanoparticles for the Detection of Ethanol, Ammonia and Acetone Gases

The design and fabrication of low-cost and fast-response α-Ag2WO4 nanoparticle sensors for the detection of gases like ethanol, ammonia and acetone are reported. Silver tungstate nanocrystals were prepared by a chemical precipitation method, and were characterized by x-ray diffraction, transmission electron microscopy and conductometric methods. The gas-sensing characteristics of α-Ag2WO4 nanoparticles fabricated in the form of thin wafers without any sensitizer coating are reported. The sensor responses of α-Ag2WO4 nanoparticles for ethanol, ammonia and acetone gases were measured as a function of temperature. All the gases showed excellent and fast sensor responses, good repeatability and short recovery times for α-Ag2WO4 nanoparticles.

Enhancement of electrical properties of manganese tungstate nanoparticles by beam irradiation

MnWO4 nanoparticles were synthesized using simple chemical precipitation method. The dielectric properties of irradiated and non-irradiated samples of monoclinic manganese tungstate nanoparticles have been studied as a function of frequency. It is found that electric properties such as dielectric constant, loss tangent and a.c. conductivity of the irradiated sample were much larger as compared to the non-irradiated sample, which has been attributed to defects and reduction in particle size caused by the beam irradiation. The present investigation observed that the electron beam irradiation is an efficient technique to modify the electrical properties of MnWO4 nanoparticles.