Low temperature sintering of microwave magnetic garnet materials

Addition of 2Ca-V or Bi-species into the Yttrium Iron garnet (YIG) materials markedly lowers the sintering temperature necessary for densifying the materials. Sintering temperature (T-s) needed for achieving a density larger than 9710 theoretical density decreases form 1450degreesC x 6h for pure YIG to 1250degreesC x 6h for 0.6 (2Ca-V)-doped YIG. (Y1.8Ca1.2)(Fe4.4V0.6)O-12 and to 1020degreesC x 6h for 1.0 Bi-doped YIG, (Y2Bi)Fe5O12, the Bi species addition not only reduces more markedly the sintering temperature necessary for achieving high density YIG materials, but also degrades loss extensively the magnetic and microwave properties of the materials. As compared with the 2Ca-V incorporation, the magnetic properties of these YIG-series materials vary with the sintering condition pronouncedly even for the samples with the same high density, which is ascribed to the change in granular structure with sintering temperature. Moreover, the linewidth of magnetic resonance peak (DeltaH) is insignificantly degraded due to Bi-incorporation. (C) 2002 Elsevier Science B.V. All rights reserved.