Synthesis and characterizations of ferrite nanomaterials for phenyl hydrazine chemical sensor applications.

This paper presents the synthesis, characterization and phenyl hydrazine chemical sensing applications of Cd0.5Mg0.5Fe2O4 ferrite nanoparticles. The nanoparticles were synthesized by facile and simple co-precipitation method and characterized in detail in terms of their morphological, structural, compositional and electrical properties. The detailed characterization studies revealed that the prepared nanoparticles are grown in high density, possessing Cd0.5Mg0.5Fe2O4 composition and exhibiting spinel cubic structure. Moreover, the prepared Cd0.5Mg0.5Fe2O4 ferrite nanoparticles were used as efficient electron mediators for the fabrication of high-sensitive, robust, reliable and reproducible phenyl hydrazine chemical sensor by simple I-V technique. The fabricated chemical sensor exhibits a highsensitivity of 7.01 microA mM(-1) cm(-2) with an experimental detection limit of 3.125 mM in a short response time of -10.0 s. This work demonstrates that Cd0.5Mg0.5Fe2O4 ferrite nanoparticles can efficiently be utilized for the fabrication of highly sensitive and reliable chemical sensors.

Magnesium-zinc ferrite nanoparticles: effect of copper doping on the structural, electrical and magnetic properties.

In this paper, Mg0.5Zn0.5-Cu(x)Fe2O4 ferrites nanoparticles were synthesized by facile co-precipitation route and characterized in detail in terms of their structural, electrical and magnetic properties as a function of Cu concentration. The prepared samples have cubic spinel phase as confirmed by X-ray diffraction patterns. The decrease of the lattice constant and increase of X-ray density indicate the solubility of Cu ions in the spinel lattice. The AC conductivity measurements between 300 K and 773 K at different frequencies 1 KHz up to 1 MHz, showed two different behaviors as semiconductor-like at high temperature and frequency depending behavior associated with dispersion phenomena at low temperatures. The conduction mechanism in the system is influenced by Cu concentration and the dominant one is the hopping conduction mechanism. Dielectric measurements at the same conditions of temperatures and frequencies exhibited that the dielectric loss increases with increasing the temperature and decreasing the frequency indicating the semiconducting nature of the ferrite compounds. An anomalous behavior of the dielectric loss is observed in samples with high Cu content which explained in terms of resonance between frequency accompanied the electronic hopping and the frequency of the external electric field. The analysis of Mössbauer spectra revealed that copper free compound is super-paramagnetically relaxed in nature and zinc free compound demonstrates ferrimagnetic order. Moreover, hyperfine field spectrum shows the migration of Cu ions from octahedral to tetrahedral site in zinc free compound.

Influence of calcium ions on the structural and magnetic properties of Cd-Mg ferrites nanoparticles.

Cadmium magnesium ferrites doped with calcium having the chemical formula Cd0.5Mg0.5-x Ca(x)Fe2O4 (0.0 < or = x < or = 0.3) were prepared by the Co-precipitation method. X-ray diffraction analysis confirmed the formation of a single phase with spinel crystal structure for the samples. The lattice parameter is determined for each composition and has been found to increase from 8.505 angstroms to 8.626 angstroms with increasing calcium concentration. Cation distribution for the studied ferrite system is proposed in terms of the structural and magnetic properties by means of X-ray diffraction (XRD), infrared spectroscopy (IR), vibrating sample magnetometer (VSM) and is found to be reliable. The experimental and theoretical lattice constants show the same trend with increasing calcium concentration indicating the validity of the proposed cation distribution. The analysis of infrared spectra indicates the presence of splitting in the absorption band which may be attributed to the presence of small amounts of Fe2+ ions in the ferrite system. The appearance of a shoulder around 700 cm(-1) suggests the presence of calcium ions in the tetrahedral site. The addition of non magnetic calcium ions in the ferrites suppressed the A-interaction and developed a B-B interaction, which is reflected in reducing the saturation magnetization in the present samples. The coercive field (H(c)) is also found to increase by increasing of Ca2+ concentration and has been explained on the bases of direct relationship with anisotropy constant.

Magnetic Nanoparticles: Synthesis, Characterization and Magnetic Properties of Cobalt Aluminum Ferrite.

Nanoparticles of the ferrite system CoFe(2-x)Al(x)O4 (x = 0.0, 0.3, 0.7 and 1.0) were synthesized through the co-precipitation technique. Thermal decomposition process and formation of a single crystalline phase were followed using thermal differential analysis technique (DTA). X-ray powder diffraction patterns of the samples confirmed the formation of a nano-size single spinel phase. The average crystallite size was found to be in the range 20-63 nm for all samples. This was further confirmed by TEM of one of the samples, with concentration x = 1.0 which was found statistically to be 27 nm. This agrees well with the value of 24 nm deduced by means of X-ray diffraction method for the same sample. A considerable decrease in the intensity of the octahedral bands is observed as the aluminum concentration increases, and even vanishes completely at x = 1.0 indicating the migration of cations between the octahedral and tetrahedral sites. The magnetic hysteresis loops at room temperature showed decrease in both, coercivity and saturation magnetization as the non-magnetic Al3+ ions content increases. The relative values of M(r0/M(s) were found to be between 0.44 and 0.31 for the samples with a remarkable change in the squareness of the loops. This is highly beneficial for the microwave and memory devices applications of these nano sized ferrite system.

Synthesis and Characterization of Zinc Oxide Nanosheets for Dye-Sensitized Solar Cells.

Zinc oxide (ZnO) nanosheets were synthesized by a simple and facile hydrothermal process and characterized in terms of their morphological, structural, compositional, optical and photovoltaic properties. The detailed characterization revealed that the synthesized ZnO material possess nanosheet morphologies which are grown in very high density, possessing well-crystallinity with wurtzite hexagonal phase and exhibiting good optical properties. Further, the synthesized ZnO nanosheets were used as photoanode material to fabricate efficient dye-sensitized solar cell (DSSC). The fabricated DSSC shows an overall light-to-electricity conversion efficiency of -1.57%, open-circuit voltage (V(OC)) of 0.552 V, short-circuit currents (J(SC)) of -7.2 mA/cm2 and fill factors (FF) of 0.40.

Pulled elbow--not the effect of hypermobility of joints.

A detailed description of pulled elbow is missing from standard orthopaedic text books. Recently it has been reported that the prevalence of hypermobility among children with pulled elbow is higher than that in the normal population and that pulled elbow can be considered to be a consequence of joint hypermobility. Two hundred children with pulled elbow comprising 106 girls and 94 boys (age range 3-84 months, mean age 24 months) were treated and evaluated for signs of hypermobility in a prospective study. Hypermobility of joints was noted in 17 (8.5 per cent) of children who had a pulled elbow while in the 71 children in whom there had been more than one episode, the rate of hypermobility was 8.4 per cent. Comparison of these results with a control group of 100 normal children, in whom 10 (10 per cent) exhibited hypermobility, showed no association between joint hypermobility and an increased incidence of pulled elbow. The anatomical construction of the radial head, relative plasticity of the cartilage and the immature annular ligament in young children possibly predisposes them to pulled elbow, the incidence of which is increasing in our modern physically competitive society where children are participating in a wide range of physically demanding sports activities. Pulled elbows can also occur in children with hypermobility of joints, but there is no evidence that the incidence has increased.