| 摘要 |
<p>PROBLEM TO BE SOLVED: To make it possible to take advantage of the characteristics of Co-, Bi-substd. rare earth iron garnet having the excellent wavelength characteristic and temp. characteristic of Faraday rotation and to further lower the light absorption coefft. thereof. SOLUTION: This method consists in substituting part of the component atoms of the Co-, Bi-substd. rare earth iron garnet for bivalent positive elements exclusive of Co and subjecting the single crystal to a reduction treatment in an atmosphere of a low hydrogen concn. The bivalent positive elements to be substituted are Co or Mg, etc. The growth of the crystal is preferably a LPE method and the CaO/Fe2O3 (molar ratio) in the raw material is specified to >=0.025. The atmosphere of the low hydrogen concn. is a gaseous nitrogen atmosphere (total pressure 1 atm.) of 1.5 to 4.5 vol.%. The reduction treatment is preferably executed at a holding temp of 400 to 500 deg.C and a holding time of <=150 minutes in the atmosphere.</p> |
