Nanostructures (NSs) of basic composition Sn 1− x Fe x /2 Co x /2 O 2 with x =0.00, 0.04, 0.06, 0.08 and 0.1 were synthesized by citrate-gel route and characterized to understand their structural, electrical and magnetic properties. X-ray diffraction and Raman spectroscopy were used to confirm the formation of single phase rutile type tetragonal structure. The crystallite sizes calculated by using Williamson Hall were found to decrease with increasing doping level. In addition to the fundamental Raman peaks of rutile SnO 2 , the other three weak Raman peaks at about 505, 537 and 688 cm −1 were also observed. Field emission scanning electron microscopy studies showed the emergence of structural transformation. Electric properties such as dc electrical resistivity as a function of temperature and ac conductivity as a function of frequency were also studied. The variation of dielectric properties with frequency reveals that the dispersion is due to Maxwell–Wagner type of interfacial polarization in general. Hysteresis loops were clearly observed in M–H curves of Fe and Co co-doped SnO 2 NSs. However, pure SnO 2 nanoparticles (NPs) showed paramagnetic behaviour which vanished at higher values of magnetic field. The grain and grain boundary contribution in the conduction process is estimated through complex impedance plot fitted with non-linear least square (NLLS) approach which shows that the role of grain boundaries increases rapidly as compared to the grain volume with the increase of Fe and Co ions in to system.

Structural, electrical and magnetic properties of (Fe, Co) co-doped SnO2 diluted magnetic semiconductor nanostructures

Optical and magnetic characterizations of zinc substituted copper ferrite synthesized by a co-precipitation chemical method

A review on electrical and gas-sensing properties of reduced graphene oxide-metal oxide nanocomposites

Nanomaterials for high frequency device and photocatalytic applications: Mg-Zn-Ni ferrites

Red phosphorus as a novel visible-light-responsive and metal-free photocatalyst has attracted extensive attention in the area of energy conversion and environmental remediation. Herein, nano-sized red phosphorus photocatalyst was synthesized via a hydrothermal and ultrasonic method and used for reduction of Cr (VI) for the first time. The as-prepared photocatalysts were characterized by XRD, UV–Vis-DRS, XPS, SEM, TEM and photoelectrochemical measurements. Compared to bulk red phosphorus, nano-sized red phosphorus exhibit a significantly enhanced photocatalytic activity for reduction of Cr (VI) due to the greatly reduced charge transfer resistance and enhanced adsorption capability of Cr (VI).

Photocatalytic reduction of Cr (VI) on nano-sized red phosphorus under visible light irradiation.

Materials reduced to the Nano scale can exhibit different properties compared to what they exhibit on a micro scale, enabling unique applications. When TiO2 is reduced to Nano scale it shows unique properties, of which the electrical aspect is highly important. This paper presents increase in the energy gap and decrease in conductivity with decrease in particle size of pure Nano TiO2 synthesized by hydrolysis and peptization of titanium isopropoxide. Aqueous solution with various pH and peptizing the resultant suspension will form Nano TiO2 at different particle sizes. As the pH of the solution is made acidic reduction in the particle size is observed. And it is confirmed from XRD using Scherer formula and SEM, as prepared samples are studied for UV absorbance, and DC conductivity from room temperature to 400°C. From the tauc plot it was observed, and calculated the energy band gap increases as the particle size decreases and shown TiO2 is direct band gap. From Arrhenius plot clearly we encountered, decrease in the conductivity for the decrease in particle size due to hopping of charge carriers and it is evident that, we can tailor the band gap by varying particle size.

Effect of particle size on band gap and DC electrical conductivity of TiO2 nanomaterial

In this work TiO2 nanomaterial of different particle size were synthesized by varying the pH of the solution by hydrolysis and peptization method. These samples were characterized by XRD, UV and SEM. The XRD reveals the formation of anatase phase form of TiO2 nanoparticles having the particle size in the range 15 nm to 35 nm. The calculated band gap values by Tauc plot for the prepared samples increases with decrease in particle size. These samples are pelletized to study the dielectric properties using Impedence Analyzer Interface in the frequency range from 1 Hz to 1 M Hz. From the dielectric studies it was observed that dielectric constant, tanδ and dielectric loss were maximum in lower frequency range, as the frequency increases these dielectric parameters decreases rapidly at low frequency region and almost constant values were recorded at higher frequencies. At lower frequencies, the dielectric parameters (dielectric constant, loss, and tanδ) increases with increase of pH up to pH 8 due to space cha...

Influence of particle size on band gap and dielectric properties of TiO2 nanomaterials

Influence of zinc on the structural and electrical properties of cerium oxide nanoparticles

In this work, the optical and dielectric properties of Co doped SnO2 nanoparticles were studied using a.c. impedance spectroscopy. X-ray diffraction (XRD) confirmed that the Co doped SnO2 powder samples have the same tetragonal structure as pure SnO2 nanoparticles. The structural, surface morphological studies, compositional analyses and optical energy band gap were investigated by XRD, Scanning electron microscopy (SEM), Energy Dispersive X-ray Analysis (EDAX), and UV–Vis Spectroscopy. It is evident from the XRD result that annealed SnO2 samples exhibits tetragonal crystal structure with crystallite size ranging from 8 to 12 nm. The optical band gaps value of doped SnO2 nanoparticles were calculated to be in the range 5.33–5.8 eV. Impedance spectroscopy was carried out at room temperature in the frequency range of 100 kHz–14 MHz to explore the electrical properties of Sn1−xCoxO2 nanoparticles. For all the Co doped SnO2 samples prepared with Co content x ≤ 0.04, the SnO2 lattice contracts with the increasing dopant concentration. The dielectric constant, dielectric loss and a.c. electrical conductivity decrease with the increase in Co doping concentration. The decrease of dielectric constant and dielectric loss of the nanomaterial with respect to increasing frequency suggests that this nanomaterial can be employed in the fabrication of devices used at high-frequencies.

Influence of dopant on structural, optical and dielectric properties of Sn1−XCoxO2 nanoparticles

ZnO nanoparticles of different size were prepared by varying the molar ratio of glycine and zinc nitrate hexahydrate as fuel and oxidizer (F/O molar ratio = 0.8, 1.11, 1.7) by simple solution combustion method. Powder samples were characterized by UV-Visible spectrophotometer, X-ray diffractometer (XRD), Scanning electron microscope (SEM). LPG sensing measurements were carried out in the temperature range 523-673K. It was found that, ZnO nanoparticle thick film prepared from F/O molar ratio 1.7 has maximum sensitivity of 5.20% for 520ppm of LPG at 623K compared to other thick films.

M. P. Rajeeva

Papers

Effect of particle size on band gap and DC electrical conductivity of TiO2 nanomaterial

Influence of particle size on band gap and dielectric properties of TiO2 nanomaterials

Influence of zinc on the structural and electrical properties of cerium oxide nanoparticles

Influence of dopant on structural, optical and dielectric properties of Sn1−XCoxO2 nanoparticles

Effect of fuel to oxidant molar ratio on particle size and LPG sensing properties of ZnO nanoparticles prepared by simple solution combustion method.