Combining Soft Chemistry and Spark Plasma Sintering to Produce Highly Dense and Finely Grained Soft Ferrimagnetic Y₃Fe₅O₁₂ (YIG) Ceramics

Abstract

We report the synthesis of yttrium iron garnet (YIG) combining soft chemistry route, namely the polyol process, and spark plasma sintering (SPS) technique. The polyol process produced an intermediary amorphous phase containing both iron and yttrium cations in the desired ratio. They were annealed at 400°C in air to decompose the organic content of the reaction (polyol and acetate). To achieve the garnet phase, the polyol‐obtained precursor was subjected to reactive SPS treatment at a temperature of 750°C, far below the typical temperatures (1350°C) used in the classic solid‐state reaction process. In 15 min pure and high‐density Y3Fe5O12 ceramic, with about 100 nm sized crystalline grains, was obtained. We report as well the characterization of the initial amorphous phase and the obtained YIG by X‐ray diffraction, scanning electron microscopy, Fourier‐transform infrared spectroscopy, 57Fe Mössbauer spectrometry, and magnetization measurements.

Microwave Absorption in Nanostructured Spinel Ferrites

“…SPS has been used to consolidate spinel [37], garnet [38], and hexagonal ferrites [39]. In the case of spinel Ni0.5Zn0.5Fe2O4 ferrites, samples prepared in the form of 6-8 nm nanoparticles by the forced hydrolysis in a polyol method [12], were consolidated by SPS at temperatures in the 350-500°C range by times as short as 5 min.…”

An integrated approach to doped thin films with strain-tunable magnetic anisotropy: powder synthesis, target preparation and pulsed laser deposition of Bi:YIG

“…This processing technique takes advantage of benefits of simultaneous application of electric current and pressure which allows for dramatically decreased processing time and temperatures making it possible to retain the nanostructure. [20] The XRD pattern of the CAPAD processed target (Fig. 2b) indicates the complete phase transformation to Bi:YIG (no evidence of Bi:YIP or BiFeO3 phases) during consolidation with minor Bi2O3 phase segregation.…”

Sintering and Reactive Sintering by Spark Plasma Sintering (SPS)

“…A convenient YIG precursor can be prepared by hydrolysis in a polyol method, followed by processing by RSPS to obtain a nanostructured garnet phase [49], with the general magnetic properties of bulk YIG. The intermediate solid phase is amorphous (Figure 6) with the required Y/Fe stoichiometric ratio.…”

“…Temperature-resolved X-ray diffraction patterns of the polyol-synthesized YIG precursor. At about 600°C, yttrium orthoferrite (YFeO 3 ) is formed, which then transforms into YIG at higher temperatures [49].…”