Line Widths in Polycrystalline Yttrium Iron Garnet

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Abstract
The line widths at the half-power point for ferromagnetic resonance in a number of polycrystalline yttrium iron garnet samples have been measured at 16 kmc. It has been determined that, starting with mixtures of Y2O3 and Fe2O3, sound parts with small grain size and having line widths as low as 35 to 40 oersteds can be obtained on the iron-rich side of stoichiometry in Y3Fe5O12. However, narrower line widths (∼20 oersteds) in large grained materials are obtained by using less than the stoichiometric amount of iron and firing at temperatures higher than 1450°C. This is due to minimizing the disrupting influences of oxygen loss in iron-rich areas at high temperatures. Line widths do not appear to be broadened by the addition of small amounts of nickel, cobalt, or manganese to convert excess iron to high resistance forms of spinel in the iron-rich compositions.