Venkatapathy Ramasamy's research while affiliated with Anna University, Chennai and other places

An attempt of synthesizing Bismuth Iron Tri Oxide (BiFeO3–BFO) nanopowder using the sol-gel route at various slotted calcination temperature and time was made to identify the minimum and as well as the optimum temperature required for obtaining single phase powders with minimum crystallite size and strain. The X-ray Diffraction study revealed that BFO demands a minimum temperature of 450 °C and a calcination time of 3 h for crystallizing in a multiferroic rhombohedral phase. The average crystallite size, space group of the unit cell and the crystalline strain were computed from Williamson-Hall (W–H) analysis for the entire range of temperature studied. In order to validate the experimental results, Multi-Criteria Decision Making (MCDM) methodology based Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) and M-TOPSIS techniques have been adopted to choose the optimized set of experimental conditions for the simple synthesis of BFO nanoparticles relatively at a lower temperature with minimum strain. Fruitful results as deduced from the optimisation techniques presents the fact that the ideal process parameters arrived from MCDM approach agrees with the experimental observations. The obtained results have been discussed in detail.

Perovskite types of nanocomposites of BiFeO3-GdFeO3 (BFO-GFO) has been synthesized using sol-gel route for the first time. The nanocomposite powders were characterized by powder X-Ray diffraction (PXRD) to confirm the existence of mixed crystallographic phases. EDX analysis on nanocomposites estimates the composition of individual element present in BFO-GFO matrix. The induced strain upon loading GdFeO3(GFO) in BiFeO3 (BFO) matrix has been computed with the aid of Williamson -Hall (W-H) plot. Surface morphologies of nanocomposite powders has been studied using Field Emission Scanning Electron Microscope (FESEM) images. The observed changes in the band gap energies of nanocomposite powders due to the inclusion of GFO has been ascertained from the tauc plots. PL emission of BFO upon loading GFO found to have detected in the IR region due to defect level transition. Finally, the methylene blue dye (MB) degradation characteristics of BFO, GFO and the nanocomposite powders of BFO-GFO have also been studied. The overall results obtained has been discussed in detail.

In the present work, nanocomposites of BiFeO3–WO3 (BFO–WO3) have been successfully synthesized for the first time by a single step sol–gel method. The main objective lies in enhancing the photocatalytic activity of BiFeO3 by modifying it with a WO3 matrix. Powder x-ray diffraction studies on BFO–WO3 confirm the presence of the monoclinic character of WO3 along with rhombohedral BFO. In addition, elemental mapping using energy dispersive x-ray analysis ascertains the existence of tungsten ions in the BFO matrix. Field emission scanning electron microscopy analysis on pure and nanocomposites depicts the distinct morphologies of the nanoparticles upon modification of BFO with WO3. From the UV–Vis–NIR spectrum, it has been noticed that there is a reduction in the band gap energy from 1.8 eV (BFO) to 1.5 eV (BFO–WO3) suggesting the increase in the absorption of a visible portion of light upon loading of WO3 in BFO. Thermogravimetric analysis/differential thermal analysis trace of BFO–WO3 nanocomposites shows that there is a suppression of the multiferroic character of BiFeO3, when it is modified with WO3. However, the photodegradation of methylene blue using BFO–WO3 nanoparticles found to have been enhanced to 91%. The increase in dye removal property may be due to the fact that the higher surface area of nanocomposites due to the incorporation of WO3 particles. The other significant results have been discussed in detail.