C.A. Cortés-Escobedo

Enhancement in Curie Temperature of Yttrium Iron Garnet by Doping with Neodymium

The effect of the substitution of Y3+ by Nd3+ on the structural and magnetic properties of neodymium-doped yttrium iron garnet, NdxY3−xFe5O12 with x in the range of 0–2.5, is presented. Oxide powders of Fe2O3, Nd2O3, and Y2O3 were mixed in a stoichiometric ratio and milled for 5 h using high-energy ball milling, before being uniaxially pressed at 900 MPa and annealed at 1373 K for 2 h to obtain NdxY3−xFe5O12 (0 ≤ x ≤ 2.5). It was found that the mechanical milling of oxides followed by annealing promotes the complete structural formation of the garnet structure. Additionally, the X-ray diffraction patterns confirm the complete introduction of Nd3+ into the garnet structure with a neodymium doping concentration (x) of 0–2.0, which causes a consistent increment in the lattice parameters with the Nd3+ content. When x is higher than 2.0, the yttrium orthoferrite is the predominant phase. Besides, the magnetic results reveal an increase in the Curie temperature (583 K) as the amount of Nd3+ increases, while there was enhanced saturation magnetization as well as modified remanence and coercivity with respect to non-doped YIG.

Characterization of Ceramic Materials synthesized by Mechanosynthesis for Energy Applications

The close relationship between processing, structure and properties of materials is well known. Some of the most useful tools to elucidate the best choice in processing for a given application are scanning electron microscopy (SEM), transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), selected area electron diffraction (SAED) and x-ray diffraction (XRD). In this chapter we will focus on the application of these techniques to the characterization of ceramic materials processed by mechanosynthesis, evaluating the effect of the milling process on their physical properties.