DCMPMS Seminars

Transport Properties of Some Transition Materials Doped II-VI Semiconductor Nanoparticles

by Ms. Sayantani Das (Ph.D. Student, University of Calcutta, Kolkata)

Thursday, March 9, 2017 from to (Asia/Kolkata)
at AG80
Description
Nanoparticles of pure and iron (5 % and 10 %), cobalt (2%, 5% and 10%) doped cadmium selenide (CdSe) and nickel (5%, 7% and 10%) doped cadmium telluride (CdTe) have been synthesized by soft chemical route. The particle size and the nano‒crystalline nature of the materials are confirmed using transmission electron microscopy and scanning electron microscopy. X-ray diffraction patterns show the structure of the prepared samples. The band gap of the materials is obtained using Tauc relation to UV-visible spectra. The Raman and infra-red spectra of the samples are analyzed to obtain the vibrational modes of the samples. Kissinger equation is applied to the thermo-grams of differential scanning calorimeter to calculate the activation energy of pure and doped nanoparticles. The frequency dependence of the dielectric response of the materials has been investigated using alternating current impedance spectroscopy at various temperatures. The most probable relaxation times obey the Arrhenius law. An analysis of real and imaginary parts of the dielectric constant has been performed by considering the distribution of relaxation times. The complex impedance plane plot has been analyzed by an equivalent circuit consisting of two serially connected R-CPE units, each containing a resistance (R) and a constant phase element (CPE). The observed electrical data are analyzed in the impedance and conductivity formalisms. The frequency dependent conductivity spectra at various temperatures follow the Jonscher’s power law. Field dependent (M-H) and temperature dependent (M-T) magnetization study of the samples has been carried out at room temperature and low temperature. Curie-Weiss temperature θ of the samples has been estimated from 1/ χ vs. T plots.