Nanocrystalline composites based on CdCO3 and Mn3O4: Synthesis and properties

With the aim of discovering new useful materials we have attempted to synthesize pure and sulfur (2.5 and 5.0 wt%) doped (Mn3O4)(x)(CdCO3)(1-x) nanocomposites (x = 0.0, 0.25, 0.5, 0.75 and 1.0) by a simple microwave assisted solvothermal method using a domestic microwave oven with the easily available chemicals. The structural and chemical characterizations were done by carrying out powder X-ray diffraction (PXRD), and energy dispersive X-ray spectroscopic (EDX) measurements. Scanning electron microscopic analysis (SEM) was carried out to study the morphology of the nanocrystals. The average crystallite sizes were estimated using the Scherrer formula and found to vary from 6.37 to 28.95 nm. The prepared samples were optically characterized by carrying out UVeVis spectral measurements. The optical bandgap energies are found to vary within 2.4-2.9 eV for all the nanocrystals prepared except for the end members. The results of optical absorption measurements on pure and S2- added CdCO3 nanocrystals indicate that they are expected to be useful in sunscreen devices. From the thermogravimetric (TGA) and differential thermal (DTA) analyses the decomposition temperatures of the samples were found. From the electron paramagnetic resonance (EPR) analysis the g-factor values were determined and it varies from 2.1493 to 1.9995 for the nanocomposites. All the samples prepared were pelletized and subjected to DC and AC electrical measurements in order to characterize them electrically. The DC electrical conductivity increases with the increase in temperature (40-150 degrees C). The dielectric parameters, viz. dielectric constant (epsilon(r)), dielectric loss factor (tan delta) and AC electrical conductivity (sigma(ac)) increase with the increase in temperature. From the impedance spectra we can notice a semicircle in the high frequency region indicating the ionic conduction which is more dominant at higher temperatures. (C) 2018 Elsevier B.V. All rights reserved.