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Biomedical Applications
Series: De Gruyter STEM

Abstract

Nickel-cobalt ferrite spinels are ferrimagnetic ceramic materials that possess a great potential for application in highdensity magnetic media, recording, color imaging, ferrofluids, and high-frequency devices. A change of their structure from micro- to nano- improves their properties drastically, therefore many methods have been investigated to fabricate nanopowder of these spinels. Gel combustion method is one of them. In this research, Ni0.5Co0.5Fe2O4 nanoparticles were fabricated via gel combustion method using metallic nitrates as an oxidant and citric acid, glycine and urea as fuels and the effects of fuel type on the reaction behavior, structure and morphology of Ni0.5Co0.5Fe2O4 nanoparticles were investigated. The reaction behavior was studied by thermal analysis method (TGA-DTA), crystallite size of powders was characterized by X-ray diffraction (XRD) and their morphology was studied by FE-SEM. The results revealed that the reaction was initiated in urea, glycine and citric at 219 °C, 197 °C, 212 °C, respectively. Samples fabricated from glycine and citric acid had a pure spinel structure but the others fabricated with urea fuel had iron oxide impurity. The crystallite size of nickel cobalt ferrite nanoparticles was in the range of 58 nm to 64 nm and the nanoparticles were agglomerated.

Abstract

Nanoparticles of Li2MnO3 were fabricated by sol-gel method using precursors of lithium acetate and manganese acetate, and citric acid as chelating agent in the stoichiometric ratio. TGA/DTA measurements of the sample in the regions of 30 °C to 176 °C, 176 °C to 422 °C and 422 °C to 462 °C were taken to identify the decomposition temperature and weight loss. The XRD analysis of the sample indicates that the synthesized material is monoclinic crystalline in nature and the calculated lattice parameters are 4.928 Å (a), 8.533 Å (b), and 9.604 Å (c). The surface morphology, particle size and elemental analysis of the samples were observed using SEM and EDAX techniques and the results confirmed the agglomeration of nanoparticles and, as expected, Li2MnO3 composition. Half cells of Li2MnO3 were assembled and tested at C/10 rate and the maximum capacity of 27 mAh/g was obtained. Charging and discharging processes that occurred at 3 V and 4 V were clearly observed from the cyclic voltammetric experiments. Stability of the electrodes was confirmed by the perfect reversibility of the anodic and cathodic peak positions observed in the cyclic voltammogram of the sample. The Li2MnO3 nanoparticles exhibit excellent properties and they are suitable for cathode materials in lithium ion batteries.

Abstract

Single crystals of L-Valinium Picrate (LVP), 0.1 mol% Ni2+ doped L-Valinium Picrate, and 0.2 mol% Ni2+ doped L-Valinium Picrate were grown by low temperature solution growth method, especially by solvent evaporation technique at ambient temperature. Function groups and modes of vibration were identified by FT-IR studies. The grown crystals belong to monoclinic system which has been revealed by powder XRD. The estimated band gaps were found to be 3.86 eV for LVP, 3.72 eV for 0.1 mol% Ni2+ doped LVP, and 3.70 eV for 0.2 mol% Ni2+ doped LVP crystals, respectively. The PL excitation wavelength of the grown materials is 370 nm. All the elements (C, N, O, Ni, and Cl) as per molecular formula were present in the EDAX spectrum of the grown materials. The 0.2 mol% Ni2+ ion doped LVP materials had higher thermal stability (208 °C) than LVP and 0.1 mol% Ni2+ doped LVP.