Investigation of Complex Impedance and Modulus Properties of Nd Doped 0.5BiFeO3-0.5PbTiO3 Multiferroic Composites

0.5BiNdxFe1-xO3-0.5PbTiO3 (x=0.05, 0.10, 0.15, 0.20) composites were successfully synthesized by a solid state reaction technique. At room temperature X-ray diffraction shows tetragonal structure for all concentrations of Nd doped 0.5BiFeO3-0.5PbTiO3 composites. The nature of Nyquist plot confirms the presence of bulk effects only for all compositions of Nd-doped 0.5BiFeO3-0.5PbTiO3 composites. The bulk resistance is found to decreases with the increasing in temperature as well as Nd concentration and exhibits a typical negative temperature coefficient of resistance (NTCR) behavior. Both the complex impedance and modulus studies have suggested the presence of non-Debye type of relaxation in the materials. Conductivity spectra reveal the presence of hopping mechanism in the electrical transport process of the materials. The activation energy of the composite increases with increasing Nd concentration and were found to be 0.28, 0.27, 0.31 and 0.32eV for x=0.05, 0.10, 0.15, 0.20 respectively at 200-275 oC for conduction process.Comment: 22 pages, 12 figures, 2 tables, 34 Referenc

Mineralogical characterization and sorption properties of goethite rich iron ore from daitari, Orissa, India

The present study was an attempt to find alternative uses of goethite rich iron ore, usually not used as raw material for iron extraction, as an adsorbent for removal of anionic contaminants from water. Mineralogical characterization by optical microscope, XRD revealed the presence of substantial amount goethite in the iron ore which was also supported from the TG-DTA and FT-IR results. On heating in air, the goethite content was completely converted to hematite at 400°C. The sorption behaviour of the untreated (GRI-0) and heat treated iron ore were studied using aqueous phosphate solution as the adsorbate with respect to effect of pH, initial phosphate concentration, amount of adsorbent, interfering anions and heat treatment. Phosphate uptake was seen to increase with increasing temperature of heat treatment, attains a maximum value at 300°C and thereafter decreased on further increase of temperature. The experimental equilibrium adsorption data were fitted well to Langmuir isotherm model. The complete desorption of adsorbed phosphate at pH ≥ 12.0 indicated the adsorption of phosphate was reversible and may be reused further. The results obtained could be useful for considering GRI-0 as adsorbent for removal of phosphate ions from contaminated water bodies

Study of Kinetics Involved in Oxidation of Nonferrous Metal Sulphides

In the present investigation, an attempt has been done to study the simultaneous effects of the major processing variables on the extent of oxidation of commercially pure sphalerite ore pellets. These process variables taken into consideration were time and temperature. The oxidation was carried inside a muffle furnace where there was mild oxidation in the presence of atmospheric air. The pellets were charged for roasting inside the furnace in a graphite crucible. This process of roasting was carried out at four temperatures 7500 C, 8000 C , 8500 C and 9000 C .The project goal is to compare the oxidation or roasting at different temperature and time. At all instance of comparison one of the parameter was kept constant. The percentage (degree) of oxidation of sphalerite pellets was calculated at 15, 30, 45 and60 minutes, after the furnace reached the predetermined oxidation temperature. The experiments were statistically designed such that the effect of each variable can be quantitatively assessed and compared. The results showed that, temperatures above 8500C, time remaining constant, with the increase in temperature there is increase in the rate of oxidation (roasting) of sphalerite ore pellets. Further more for a constant temperature with the increase in time of exposure, rate of oxidation of Sphalerite (ZnS) pellets increases. This is valid for temperature range above 8500C. Another observation was made that temperature remaining constant, the rate of oxidation of Sphalerite (ZnS) ore pellets increases with time of exposure to attain a maximum limit than suddenly decreases followed by increment in the rate again. This observation was made in the temperature range of less than 8000C