سنتز مكانوشيميايي فريت نيكل-روي نانو ساختار و بررسي خواص ساختاري و مغناطيسي آن

چكيده انگليسي :

Mechanochemical synthesis of nanostructured Ni Zn ferrite and investigation of its structural and magnetic properties Maisam Jalaly Maisam Jalaly@yahoo com 15 Apr 2009 Department of Materials Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language FarsiAbstractNanocrystalline Ni Zn ferrite powders with spinel structure was prepared by mechanochemical route Inorder to formation of this ferrite with composition of Ni0 5Zn0 5Fe2O4 it was used the stoichiometricmixture of NiO ZnO and Fe2O3 Initial materials was milled in various times up to 60h X ray powderdiffractometry XRD scanning electron microscopy SEM simultaneous thermal analysing STA Fourier transform infrared spectroscopy FTIR ac susceptometer and vibrating sample magnetometer VSM were carried out to characterize the structural chemical and magnetic aspects of ferrite Thecrystallite size of final product after 60 h of ball milling time was estimated to be 17nm by Williamson Hallequation In order to decrease crystal defects and lattice strain due to mechanical alloying and reduction ofremained initial oxides annealing treatment was done in different times and temperatures The condition of800 C and 2h was selected as a suitable condition for annealing and grain size increased to 45 nm afterannealing at this condition Ni1 xZnxFe2O4 x 0 0 1 0 3 0 5 0 7 0 9 1 was synthesized with previousconditions to study the effect of composition on the structural and magnetic properties XRD resultsshowed that lattice parameter of ferrite increased by increasing Zn content x Powder particles in allcompositions had a spherical morphology and diameter size of around 100nm Thermal analysis was usedto determine the mechanism of formation of Ni Zn ferrite The formation of NiZnFe2O4 phase appeared toinvolve two stages development of Zn ferrite by diffusion of ZnO in Fe2O3 followed by diffusion of NiO inZn ferrite to form Ni Zn ferrite FTIR results showed that the ferrite has two specific bands in 420 and590cm 1 which former depends on octahedral sublattice and the latter corresponds to tetrahedral sublattice The tetrahedral band was shifted to higher frequencies but octahedral band had no displacement as Zncontent increases The saturation magnetization and coercivity of samples was obtained by plotting ofhysteresis loop of B H The results showed that the saturation magnetization of milled ferrite was to belower than that of annealed ferrite And it is shown the x 0 7 and 0 9 samples exhibited the non saturatedmagnetization zero remanence and zero coercivity These samples indicated also the superparamagnetismbehavior The measurement of ac susceptibility of different samples showed that the x 0 7 sample had athermal peak in 280K which shifted to higher temperatures as frequency increases Therefore theNi0 3Zn0 7Fe2O4 ferrite was in the superparamagnetism regime The magnetic dynamic behavior of thissample was agreed by Vogel Fulcher law In order to investigate the effect of copper element on theproperties of ferrite two compositions of Ni0 5Cu0 1Zn0 4Fe2O4 and Ni0 5Cu0 3Zn0 2Fe2O4 was formed XRD SEM FTIR and VSM analysis were done on these samples The lattice constant decreased with increasingCu content The octahedral and tetrahedral bands displaced when the Cu doping level increases Thesaturation magnetization of ferrite decreased and its coercivity increased by increasing Cu concentration Key WordsMechanical Alloying Nanostructured Magnetic Materials Ni Zn Ferrite

جلالي، ميثم

سنتز مكانوشيميايي فريت نيكل-روي نانو ساختار و بررسي خواص ساختاري و مغناطيسي آن

فريت هاي مغناطيسي , تفجوشي