Abstract
Rare earth garnets (REE3Fe5O12) have magnetic-electric and optical properties that can be used in transmitters, microwave and data storage devices. These properties depend mainly on partial or total substitution of the cationic sites, as well as by the synthesis method used. Therefore, in this work was studied the influence of the substituting cation on the structural and morphological properties of new garnets with formula Sm3−xREExFe5O12 with x = 0.0 - 1.0; obtained by the solid-state reaction method. Characterization of samples was carried out by XRD, Rieltveld refinement, SEM and Raman spectroscopy. The results showed that the substitution favors system stability and formation of garnets single phase with cubic structure and space group of Ia3d (230) at temperatures lower than reported by other authors. The substitution generated a decrease of the lattice parameters, the crystal size and favored particle formation of the order of micrometers (from 1.3 to 3.6 µm).
Highlights
The iron-rare earth garnets REE3[Fe2](Fe3)O12 crystallize in the cubic system and present space group Ia3d (230), the unit cell is constituted by three crystallographic sites: tetrahedral site 24d (Fe2), octahedral site 16a [Fe3] and dodecahedral site 24c REE3 1
Yttrium-iron garnet (Y3Fe5O12) is the most important material in this family of oxides: it is ferrimagnetic with high Curie temperature (Tc = 260 oC), it has low coercive field (Hc) and high thermal conductivity, electrical resistivity and Verdet constant, which results in the Faraday effect or magneto-optic effect[3].Thanks to these properties, further investigations studied the effect of yttrium substitution by rare earth elements (REE) such as neodymium (Nd), samarium (Sm), gadolinium (Gd), holmium (Ho) and dysprosium (Dy) and cerium (Ce)[4]; this allowed to discover the existence of magnetic anisotropy, magneto-dielectric, magneto-electric and magneto optical effects associated with these new materials[5,6]
The analysis allowed to determine a phase classification according to the iron-samarium garnet with reference code JCPDS 01-073-1379, of cubic structure, space group Ia3d (230) and with a preferential orientation in along (4 2 0) crystal plane, which corresponds to peak with higher intensity in the theoretical X-ray diffraction (XRD) pattern
Summary
The iron-rare earth garnets REE3[Fe2](Fe3)O12 crystallize in the cubic system and present space group Ia3d (230), the unit cell is constituted by three crystallographic sites: tetrahedral site 24d (Fe2), octahedral site 16a [Fe3] and dodecahedral site 24c REE3 1 Thanks to this structural distribution, garnets can be constituted by different ions that give them remarkable magnetic-electric and optical properties[2]. It has been established that the insertion of lutetium (Lu) does not contribute to any magnetic behavior due to the absence of unpaired electrons (4f14), the net magnetic moment will be given by the unequal distribution of the octahedral and tetrahedral Fe3+ ions It presents important applications in telecommunications and data storage industry due to this magnetic-dielectric coupling[16]. It was ground, prensed into pellets at pressure of 2.5 MPa and subjected to a sintering process at 1200 oC for 20 h in order to favor the interdiffusion processes that allowed the obtention of the desired crystalline phase
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