CRYSTAL GROWTH OF HIGHLY BI-SUBSTITUTED MAGNETIC GARNETS FOR MAGNETO-OPTIC DEVICES.

The growth of large single crystals of Gd//3 minus //xBi//xFe//5O//1//2 (GdBiIG) by the stirring and scooping method and a 0. 8- mu m isolator fabricated from this material are discussed. In single-crystal growth experiments, Bi//2 O//3 was primarily used for flux, and oxides of Pr, Eu, Gd, Y, Tb, Yb or Lu for rare-earth elements. Using the ordinal flux method and the stirring and scooping method the samples were gradually cooled (0. 5 - 2 degree C/hr) from a temperature of approximately 1300 degree C. The resultant growth ranges for YBiIG were 30 mo1% (or less) for Y//2 O//3 , 28 - 70 mo1% for Fe//2 O//3 , and 26 - 60 mo1% for Bi//2 O//3 . In compositions with much Fe//2 O//3 , alpha minus Fe//2 O//3 and BiFeO//3 grew easily, and in those with much Bi//2 O//3 , YFeO//3 grew easily. Also, when there were a lot of Y//2 O//3 , the melting point rose and it was difficult to grow single crystals. A small 0. 8 minus mu m light isolator with a RBiIG single crystal as its Faraday element was constructed. The insertion loss at 0. 8 mu m was approximately 1. 5 - 2. 5 dB and the light absorption ratio 32 dB or greater. The volume of this light isolator was 1/65 that of isolators using Faraday glass. Excellent results were obtained when