Influence of flux composition and growth temperature on the octahedral incorporation of rare-earth cations in rare-earth iron garnet

Abstract

Epitaxial films of RE₃Fe₅O₁₂, where RE is Y or Ho, or the combination of Y or Ho with another rare‐earth, were grown on (111) Gd₃Ga₅O₁₂ substrates at nearly identical temperature from melts for which R₃ = PbO/2B₂O₃ = 31.2, 7.4, or 5.0. The octahedral substitution for Fe was calculated from the Curie temperature and lattice constant. B₂O₃ was found to inhibit the octahedral substitution of rare‐earth cations. In the case of RE = Y or Ho, this substitution was RE_0.055 in the formula unit at R₃ = 31.2, and approximately RE_0.040 at R₃ = 5.0. Lu was found to have a five‐fold greater preference for octahedral substitution than Y or Ho. Octahedral preference was found to correlate well with ionic radius. Boron incorporation was small. Growth rate has a negligible effect on octahedral substitution, but reducing the growth temperature increases the octahedral substitution of rare‐earth by about one‐third percent per °C.