Rohini S. Bhalerao-Panajkar
@viit.ac.in
Professor Engineering & Applied Sciences
Vishwakarma Institute of Information Technology
RESEARCH INTERESTS
Materials Science, Nanotechnology
Scopus Publications
Scholar Citations
Scholar h-index
Scholar i10-index
Scopus Publications
Rohini S. Bhalerao-Panajkar
IOP Publishing
Abstract Hexamethylenetetramine (HMT) capped CuO nanoparticles were synthesized by microwave assisted technique. X-ray diffraction analysis confirms the formation of monoclinic single phase of the synthesized particles. The nature of ligand bonding and an estimate of the ligand molecules on the surface of CuO particles were obtained from Fourier Transform Infrared spectroscopy and Thermogravimetric analysis, respectively. Hysteresis measurements performed at 10 and 300 K show both the core-shell nature and the impact of the ligand. Dielectric measurements were performed with a temperature variation of 10 to 325 K and a frequency variation over 126 kHz to 949 kHz range. Broad relaxation peaks, reduction of dielectric constant with size and the presence of anomalies at slight variance to the magnetic transitions observed in bulk material, show signatures of the impact of ligand. Impedance spectroscopic (IS) analysis shows the room temperature impedance to be dominated by grain boundaries and reveals core-shell type of behaviour with conducting grains and insulating grain boundaries. A schematic is proposed with the grain consisting of the ligand capped CuO clusters separated by interfaces/grain boundaries.
Franziska Niederdraenk, Knud Seufert, Andreas Stahl, Rohini S. Bhalerao-Panajkar, Sonali Marathe, Sulabha K. Kulkarni, Reinhard B. Neder, and Christian Kumpf
Royal Society of Chemistry (RSC)
The detailed structural characterization of nanoparticles is a very important issue since it enables a precise understanding of their electronic, optical and magnetic properties. Here we introduce a new method for modeling the structure of very small particles by means of powder X-ray diffraction. Using thioglycerol-capped ZnO nanoparticles with a diameter of less than 3 nm as an example we demonstrate that our ensemble modeling method is superior to standard XRD methods like, e.g., Rietveld refinement. Besides fundamental properties (size, anisotropic shape and atomic structure) more sophisticated properties like imperfections in the lattice, a size distribution as well as strain and relaxation effects in the particles and-in particular-at their surface (surface relaxation effects) can be obtained. Ensemble properties, i.e., distributions of the particle size and other properties, can also be investigated which makes this method superior to imaging techniques like (high resolution) transmission electron microscopy or atomic force microscopy, in particular for very small nanoparticles. For the particles under study an excellent agreement of calculated and experimental X-ray diffraction patterns could be obtained with an ensemble of anisotropic polyhedral particles of three dominant sizes, wurtzite structure and a significant relaxation of Zn atoms close to the surface.
Rohini S. Bhalerao-Panajkar, Mandar M. Shirolkar, Raja Das, Tuhin Maity, Pankaj Poddar, and S.K. Kulkarni
Elsevier BV