Narrow Results

A series of Fe_2-xAl_xCoO₄ ferrite nanoparticles have been synthesized by sol-gel method. Powder X-ray diffraction (XRD), thermo gravimetric (TG) and differential thermal analysis (DTA), transmission electron microscopy (TEM) and IR spectroscopy analysis were employed to study structural and morphological characterization of these ferrite nanoparticles. The effect of substitution of Fe³⁺ by Al³⁺ ions on the structural properties of cobalt ferrite nanoparticles was investigated. The crystallite (D) is found in the range 39 nm to 6 nm, which decreases with increasing aluminum content. The values of lattice parameters (a), X-ray density (d_x), hopping length (L_A, L_B) decreases with aluminum content. The tetrahedral bond (d_AX), octahedral bond (d_BX), tetra edge (d_AXE) and octa edge (d_BXE) (shared and unshared) showed the linear decrease with the increasing aluminum content x. IR spectroscopy analysis revealed the chemical and structural changes taking place in the combustion reaction.

The nanoalumina particles were produced by the wire explosion process. The size and the shape of the particles were measured using Transmission Electron Microscope (TEM) studies. The Scanning Electron Microscope (SEM) studies were carried out to confirm that the particles are of sub-micron size. The compositions of the material were characterized through the Energy Dispersive Angle X-ray Analysis (EDAX) results. The Wide Angle X-ray Diffraction (WAXD) and the Fourier Transform Infra-Red (FTIR) results confirmed the nanosize powder formed by the process as crystalline γ-Al₂O₃ powder. The thermal characteristics were analyzed using Thermo-gravimetric Differential thermal analysis (TG-DTA). It is identified that the local temperature of the medium at the time of formation of nanopowder decides the phase characteristics of the powder material. The formation mechanism of nanopowder by wire explosion technique was explained in detail. The mechanism of nanopowder formation and the characteristic changes that occur during the explosion process were recorded using a high-speed digital camera.

Sediment quality strongly depends on organic matter conditions in the sediment, thus identifying organic matter conditions in sediment is very necessary. The thermal analysis (TG/DTA) is widely used to understand the ignition characteristic of sediment. It has been reported that different types of organic matter have different exoergic temperatures. Unfortunately, no any TG/DTA analysis standard has been proposed for sediment analysis. In other words, TG/DTA analysis of sediment is different from a study to another study. This study is aiming at proposal of TG/DTA analysis for identifying organic matter conditions in sediment. Different sediments collected from different littoral regions in Japan were used in the TG/DTA analysis. The sediments were first oven dried, and then were passed through 75-μm sieve. The sediments with and without passing through 75-μm sieve were used in the analysis. In the analysis, different weights (10 to 30 mg) of samples were ignited from 25 to 850°C with heating rates of 1, 5, 10, and 20°C /min. It was observed that a more accurate analysis could be obtained when the sediment less than 75-μm was used, specifically for the sediment collected from the littoral region exposed to wastewater discharge. The exothermic peak easily appeared with increasing weight of the sample, which easily identified organic matter conditions in the sediment. Moreover, mass loss on ignition of the sediment burned at ≤5°C /min was higher than that at ≥10°C /min. This ensured that organic matter was incompletely burned at≥10°C /min. It can be concluded from our results that 20-30 mg of sediment passed through 75-μm sieve should be burned at 5°C /min to obtain a more accurate analysis of organic matter conditions in sediment.