Papers by Author: Vasile Florin Tarța

Abstract: The ZnFe₂O₄/α-Fe nanocomposite powders were obtained by ball milling starting from ZnFe₂O₄ powder synthesized by classical ceramic method and commercial iron powder. Two way of milling were used for the synthesis of the ZnFe₂O₄/α-Fe nanocomposite. In both cases after milling process the phases are relatively uniformly distributed in material and zinc ferrite mean crystallite size decreases from micrometric range up to 11 nm for the first milling mode and up 48 nm for second milling mode. The ZnFe₂O₄/α-Fe nanocomposite powders were compacted by Spark Plasma Sintering method (SPS). During sintering a reaction between nanocomposite phases occurs, thus leading to the formation of ZnO and FeO. The evolution of the powders during milling and stability of the nanocomposite phases was investigated by X-ray diffraction. The powders and compacts morphology and local chemical homogeneity were investigated by scanning electron microscopy (SEM) and respectively by energy dispersive x-ray spectrometry (EDX). The influence of the sintering parameters on the stability of nanocomposites phases is studied.

Abstract: The polycrystalline nickel ferrite - NiFe₂O₄ has been obtained by ceramic route starting from a stoichiometric mixture of oxides (NiO and α-Fe₂O₃ powders). The obtained NiFe₂O₄ was subjected to high energy ball milling. The formation of NiFe₂O₄ by ceramic method and also the evolution of the powder during milling were studied by X-ray diffraction. The mean crystallite size of the NiFe₂O₄ continuously decreases with the increasing of the milling time and for all the milling time it is in nanometric range. The particles sizes are drastically reduced by milling process. For the milled samples, the particles size is ranging from tens of microns to few nanometers. The powder morphology and local chemical homogeneity were investigated by scanning electron microscopy (SEM) and respectively by energy dispersive x-ray spectrometry (EDX).