Journal Title
Title of Journal: J Theor Appl Phys
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Abbravation: Journal of Theoretical and Applied Physics
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Publisher
Springer Berlin Heidelberg
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Authors: B B V S Vara Prasad
Publish Date: 2015/08/21
Volume: 9, Issue: 4, Pages: 267-272
Abstract
Indiumsubstituted polycrystalline nickel zinc ferrites of different compositions Ni065Zn035Fe2−x In x O4 x = 000 004 008 012 016 02 have been prepared by solidstate reaction route Calcination and sintering of all samples were done in air atmosphere at 950 °C and 1250 °C respectively followed by natural cooling to room temperature Characterization of the basic composition was done by Xray diffractometry saturation magnetization and Curie temperature The effect of incorporation of larger indium ions in place of iron was studied with the help of saturation magnetization Curie temperature permeability magnetic loss factor DC electrical resistivity and dielectric properties The highest magnetization and permeability values of the present system under study are 741 emu/g and 438 for the basic composition concentration x = 0 The DC electrical resistivity was found to decrease up to x = 03 and increase thereafter The variation in the electric and magnetic properties of this ferrite system is dominated by the decrease in iron concentration Characteristic high dielectric constant values were recorded for these bulk ceramic materialsPolycrystalline spinel ferrites are extensively investigated for their usefulness in modern technology The tunable magnetic and electric properties of ferrites made them better candidates for electronic and electromagnetic applications like transformer cores inductors electromagnetic suppressors EMI microwave absorbers etc 1 2 Ferrite crystallizes into face centered cubic spinel having general formula AB2O4 where A and B are divalent and trivalent metal cations Ferrite structure comprises two types of sublattices tetrahedral A site and octahedral sites B Cations are distributed between these two sublattices in two ways without changing the lattice symmetry They are normal divalent ions occupy A site and trivalent ions occupy B site and inverse spinel divalent and trivalent ions distributed between both sites at random The properties of ferrites strongly depend on not only the method of preparation but also on the distribution of ions in the crystal latticeSeveral ferrite compositions were studied over the last few decades and some of them are found to be interesting in the application perspective In the family of spinel ferrites nickel–zinc mixed ferrites are commercially important magnetic materials because of their high saturation magnetization high electrical resistivity and low losses Owing to their moderate permeability values this mixed ferrite system has some limitations in view point of applications Thus far various kinds of substitutions were done on these materials and the effects on their properties are thoroughly studied 3 4 Among all those substituted cations incorporations of several diamagnetic divalent and trivalent ions in place of paramagnetic ions into ferrite systems were remarkably improved their magnetic and electric properties 5 6 Several researchers investigated trivalent diamagnetic ions such as Al3+ and In3+ ions but mixed results were obtained which depend on mode of preparation Furthermore In3+ ions are substituted at the expense of strong ferromagnetic iron ions which may change the interactions present within the system Previous research study of indiumsubstituted nickel–zinc ferrite systems in bulk form showed some interesting variations in the electric and magnetic properties 7 8 9 10 In those systems reasonable amount of paramagnetic ions were maintained at the expense of strong ferromagnetic ions The present research study is aimed at investigating the effect of substitution of In3+ ions in place of Fe3+ ions on magnetic and electric properties Since the substitution of indium in present system is in the place of strong ferromagnetic Fe3+ ions which are very crucial in determining the magnetic as well as electric properties of ferrites the ferrite system may undergo remarkable modifications in its behavior under the influence of electric and magnetic fieldsBecause of the intrinsic complexity and less immediate applications there is less information available on dielectric properties of Ni–Zn ferrites When this ferrite system is incorporated with suitable substituent it is possible to maintain moderate magnetic and dielectric characteristics simultaneously and these can be potential contenders for microwave absorbers and magnetodielectric applications Being diamagnetic larger in size and variable site occupancy with concentration prompted the present research study and the variations in the properties have been discussed in the limit of existing understandingThe initial ingredients were weighed in the required proportions using microanalytical balance The weighed materials were thoroughly mixed in an agate mortar–pestle for 3 h in dry medium and 3 h in acetone medium This mixture was calcined at 950 °C for 4 h in air atmosphere The presintered powder was again crushed and ground thoroughly for 3 h in acetone to promote the homogeneity among the mixture The resulting mixture was made into pellets and toroids under the pressure of 5 and 3 tons/in2 respectively using 15 polyvinyl alcohol as binder The dimensions of the pellets were of 4 mm thickness and 3 cm in diameter The toroids were of 13 mm inner diameter and 18 mm outer diameter Both the pellets and toroids were sintered at 1250 °C in air atmosphere for 2 h followed by natural cooling to room temperature The surfaces of all the samples were polished to remove any oxide layer formed during sinteringSaturation magnetization was measured by Ponderometer pendulum method described by Rathenov and Sneok 13 The ferrite samples used for measurements have the dimensions approximately 2 mm × 3 mm × 3 mm Curie temperature was measured by the experimental setup described by Soohoo 14Inductance L measurements on the toroidal samples were carried out using LCRQMETERSORTER at a small voltage of 10 mV The average dimensions of the toroidal samples used in this study are as follows outer diameter OD = 15 mm inner diameter ID = 8 mm thickness h = 45 mm All toroidal samples were wound with 30 SWG enameled copper wire and 30 turns Initial permeability at 1 kHz frequency and at room temperature was computed using mu i = fracLL 0 where L is the inductance of toroidal sample L 0 = 4606 N 2 h log OD/ID 10−9 Henry is the air core inductance and N is the number of turns
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