Importance of Intrasublattice Magnetic Interactions and of Substitutional Ion Type in the Behavior of Substituted Yttrium Iron Garnets

Studies of substitutions for iron ions in yttrium iron garnet of nonmagnetic ions which prefer exclusively (or almost exclusively) octa- BEHAVIOR OF SUBSTITUTED YIG .567 hedral sites have been reported earlier.1-2 The results of the study of the tin-substituted yttrium iron garnets led to Gilleo's statistical treatment, 3 which appeared to account well for the 0°K moments and Curie temperatures in this system as well as in those involving zirconium,2 scandium,2"1 and indium2"4 substitutions. However, the data available at the time of these developments were still not sufficient, for a complete test of the method. The study of substituted yttrium iron garnets has now been extended to systems in which substitution for Fe3~ ions is made exclusively in the tetrahedral sites (i.e., {Y 3 _ I Ca. r )[Fe 2 ](Fe^Si*)O12), equally in both octahedral and tetrahedral sites (i.e., and {Y3_2,Ca2l} [Zr x Fe 2 _ x ](Fe 3 _ I Si x )0 12 ), and unequally in the two sites (e.g., {Y3+X-VC&U-X} [Mg x Fe 2 _i](Fe 3 _,,Si,,)0i 2 , {Ys-tfCaJ [ScJ.Fe2_I] (Fe3_,,Si,,) 0 1 2 , and {Y3_x_,,Cax+i,} [ZrxFe2_x](Fe3_1/SiI/)Oi2). Analogous germanium-substituted systems have also been studied. The system {Ys-iCaJ [ZrrFe2_j](Fe 3 )Oi 2 has been reinvestigated and the study of the } [Scj-Feo-xJ(Fe 3 )Oi 2 system extended to larger values of .v. High-field measurements have been made on specimens when required. The study of the system Y3Al.rFc6_.rO124 has been extended to large values of .r, and the distribution of the ions vs x deduced.