Analysis of Ferrous Ferrite (Fe3O4)

Analysis of Ferrous Ferrite (Fe3O4)1.1 INTRODUCTIONThe naturally farering ferrite is the ferrous ferrite (Fe3O4) as Load stone. In early days it was called as ferromagnetic stuff and nonsense. L.Neel, tells us that these materials are ferromagnetic material due to uncompensated anti correspond spin arranging. Due to interesting intrinsic properties magnetic materials are classified into Ferromagnetic materials, Ferrites. In last decades , in the field of the ferrites expensive development was through by m either contributors and found to be technically, commercially useful magnetic material. These materials are at high gear frequencies, high galvanizing resistivity of magnetic temperature coefficient of shelter along with low magnetic loss.Basically, Ferrous ferrite (Fe3O4) consist double oxides FeO and Fe2O3 . The properties of these materials are alter by substituting bivalent weigh ion by divalent cation worry Cd2+,Mg2+,Ni2+,Zn2+,Cu2+,Co2+ etc. from transition element. T he spinel ferrites are represented as MFe2O4, where M is divalent cations. The magnetic properties are significantly improved by substituting trivalent iron ion by Al3+,Cr3+,Mn4+, Ti4+,Sn4+, Gd3+,Nd3+ etc. for particular applications because of their interesting magnetic and electrical properties with chemical and thermal stabilitiesGadkari A.B et.al. (2010).The applications of these materials in fields like electrical components, memory devices, microwave devices telecommunications, electronic industries, dada storage, data membering due to its high resistivity and low power losses. Ernst Schloeman et al. (2000)Ferrites are of two types,one is saturated ferrite and other is soft ferrite. The material which are easily magnetized and demagnetized, it is called soft magnetic material .That means, it can store or transfer magnetic energy in alternating or other changing wave forms. The ferromagnetic materials like iron, nickel, cobalt and some of the rare earths materials shows a uni que magnetic behavior. All the magnetic moments of the individual ions or atoms are aligned parallel to some particular direction and the unpaired electron spins line up parallel with each other in the ferromagnetic material. The region in which magnetic dipoles align parallel to each other is called a do main. The structural properties of ferrite are very important. The structural properties of ferrites mainly depends on the manufacturing process of ferriteMangalaraja R.V. et al. (2003).In fundamental science, magnetic spinel ferrites are of great importance. They are useful especially for find turn up the fundamental relationship between magnetic properties and their crystalchemistry and social organization Kalonji G.et.al.(1999). They find extensive applications in microwave devices, radar, digital recording, ferrofluids, catalysis and magnetic refrigeration systems Horvath M.P. et.al. (2007). For the spinel ferrite the general formula is AB2O4and it is consisting of an almost perfect blockish closed jammed oxygen arrangement, with the cations residing on tetrahedral and octahedralinterstices.Nowadays, magnetic materials are used in various fields. The soft magnetic materials can be attracted to a eonian magnet and the hard magnetic materials become a permanent magnet. In case of soft magnetic materials, the large magnetic fields cannot be generated to the outside but in hard magnetic materials it generates magnetic fields. The magnetic materials like iron, cobalt and nickel ordinarily reveal prominent magnetic property. In industry, the ferromagnetic materials are astray used. In case of metal and alloy magnetic materials, due to their lower electrical resistivity the initial permeability and magnetic flux density is high and loss in eddy current is large at high frequencies. Nowadays, high-frequency characteristics are more useful, so this is occurred in ferrites which is multiplying the thin films. Due to higher electrical resistivity, the soft fe rrites has excellent characteristics at high frequency. They are abundantly used for inductors or core materials of transformer. The hard ferrite is also used abundantly as permanent magnets for speakers and motors.The soft ferrite is used into an alternating magnetic field. Ferrites are chemical compounds. They are composed of a ceramic material along with iron oxide as their main component. The magnetic property of the ferrite is due the structure and the arrangement of the ions in the sub lattice.1.2 SPINEL COMPOUNDSThe word spinel which is derived from Italian spinella, diminutive of spine, thorn (from its sharply pointed crystals). In the cubic system, Spinel crystallizes forming octahedral crystals. In spinel super group there are at least 30 oxide minerals included. The majority of spinel compounds belongs to the space group Fd3m. The formula for the principal member of the group has, AB2O4 out of which A is a divalent metal ion such as magnesium, iron, nickel, manganese and zinc. The B is trivalent metal ions such as aluminium, iron, chromium and/or manganese. Also, te Ti4+ and Pb2+ etc. may occupy this site. The solid solutioning which is common process in this group of minerals that means they may contain certain percentages of different ions in any particular specimen Adams, D. M (1974). The oxygen ions are mostly larger than the metallic ions and the spinel structure can be formed by a cubic close packing of O2- ions, in most oxide structures in which the cations (e.g. Co2+, Fe3+) occupy certain interstices. So, the structure of a spinel compound and the highly symmetric structure of infield is same. The position of the A ions and the positions of carbon atoms occupied in the diamond structure is identical. In this group this could discuss the relatively high hardness and high density. The arrangement in the structure of the other ions shows the symmetry just like diamond structure. This arrangement of the ions verifies the octahedral crystal stru cture which is the predominant crystal form and also the denounce of the spinels. Now a day, there are well over a hundred compounds are reported of the spinel structure. or so of them are oxides, sulphides, selenides and tellurides and some are halides. in that location are different cations may be introduced into the spinel structure and several charge combinations are possible, therefore, almost any combination that added and balances eight positive charges of anionic charges Smyth,D.M.(2000),for sample Co2+Fe23+O4, Mg22+Ti4+O4, Li1+Al3+Ti4+O4, Li0.51+Al2.53+O4 and Na21+W6+O4, etc.In oxide spinels, there are two types of cations which do not differ in size greatly because the spinel structure is stable just now when the cations are rather medium sized and also the radii of the different ionic species in the same compound must be nearly equal. on that pointfore, similar cation combinations occur in sulphides, e.g. Zn2+Al23+S4 and Cu22+Sn4+S4. Hence, in halide spinels e.g. Li 21+Ni3+F4 and Li1+Mn23+/ 4+F4 in which cations are limited to charges of plus 1 and plus 2, give an overall cation anion ratio of 3 as 4.Most spinels divided into three series determined by a B metal represent aluminate series with Al3+ (Hercynite, Gahnite, Galaxite) a magnetite series with Fe3+ (Magnetite,Magnesioferrite, Franklinite) the chromite series with Cr3+ (Chromite, Magnesiochromite). There is extensive cationic exchange (solid solution) within each series but very little between the series King, R. J (2004).These spinels are classified on the basis of the distribution of cations in the two principal sites which are tetrahedral site (T-) and octahedral site (O-) West, A. R. (1989), into three types.1.2.1 NORMAL SPINELIn radiation pattern spinel A (BB) O4, all the divalent (A) cations placed on the tetrahedral (T-) sites and the trivalent (B) cations present on the octahedral (O-) sites. Which can be shown by the formula Atet B2oct O4. The examples of normal spinel areMgO .Al2O3 = MgAl2O4 (normal, parent mineral)ZnO.Fe2O3 = ZnFe2O4 (normal)FeO.Al2O3 = FeAl2O4 (normal)CoO.Al2O3 = CoAl2O4 (normal)MnO.Al2O3 = MnAl2O4 (normal)NiO.Al2O3 = NiAl2O4 - (normal)1.2.2 INVERSE SPINELThe antonym spinel, B (AB) O4, the divalent cations occupying on the O-sites and the trivalent cations which are equally divided among the T- and remaining other on O-sites. Which can be represented by formula, Btet A, Boct O4. The CoFe2O4 is conformably an inverse spinel with a formulaCoxFe1-x (Co1-xFe1+x) O4(with x 0)where x represents the cation distribution factor which discuss the portion of tetrahedral sites occupied by Co2+ cations Guire, M. R.D (1989).CoO.Fe2O3 = FeCoFeO4 (inverse)NiO.Fe2O3 = FeNiFeO4 - (inverse)MgO.Fe2O3 = FeMgFeO4 (inverse)1.2.3 RANDOM SPINELIt has an intermediate cation distribution, represented as B0.67 A0.33tet A0.67B1.33octO4.In this elementary unit cell of spinel structure consists eight tetrahedral and sixteen octahedral sites which are occup ied by metal ions and the extreme cases, represent completely normal and inverse spinel, Therefore, the general cation distribution can be represented as M(2)iq+M(1)1-ip+AIV M(1)p+i/2 M(2)(2-i)/2q+2BvI O4where M+(1)p+ and M(2)q+ are the minority and majority cations respectively. Hence, the first measuring rod in brackets shows the average occupancy of A-sites (coordination number of four (IV)) and the second quantity in brackets shows the average occupancy of B-sites (coordination number of six (VI)). The inversion parameter , shows the fraction of A-sites acquired by majority ions.