Microstructure and hysteresis curves of samarium-holmium-iron garnet synthesized by coprecipitation

Abstract

An investigation was made into the synthesis and magnetic properties of Sm(3-x)Ho xFe5O12 (samarium-holmium-iron) garnet ferrite, as yet absent from the literature. The material in question was synthesized by co-precipitation, starting from hydrated chlorides of rare-earth elements and ferrous sulfate, and the mixed hydroxide co-precipitate was calcined at 1000 °C. Using PVA as a binder, rectangular cross section-shaped compacts were produced by means of steel-die pressing, drying and sintering from 1200 to 1450 °C. The main conclusions of this study were that the coercive force decreases as the sintering temperature increases, and that the effect of substituting holmium for samarium in SmIG is entirely different from that provided by replacing yttrium by gadolinium in YIG, which is the most important result of this work. An in-depth investigation will be necessary to determine the correlation between microstructure/magnetic properties and ceramic processing variables

Terbium–yttrium–iron garnet revisited

“…In fact, the Tb 2.4 Y 0.6 Fe 5 O 12 sintered at 1400 • C presented a saturation induction of 2.53 kG (at 64.68 Oe field strength) and a coercive force of 1.56 Oe. These results are in good agreement with those obtained for Ho 2.4 Sm 0.6 Fe 5 O 12 sintered at 1450 • C for 5 h in air [30], for which B s = 2.7 kG (1.80 emu/g), by both hysteresisgraphy and vibrating sample magnetometry, and coercive force = 3.89 Oe.…”

“…2(b) presents the XRD patterns for samples (x = 0.6) sintered at 1350 and 1400 • C for 4 h, showing indexed peaks of Tb 2.4 Y 0.6 Fe 5 O 12 , the unique TbYIG phase present and identified as closely fitting with Tb 2.5 Y 0.5 Fe 5 O 12 referred to in previous report [20]. There is already well-known compositiondependent restriction to the formation of mixed Tb-Y-Fe garnets, as it has been previously observed in Sm-Ho-Fe garnets [30]. Fig.…”