Characterization of the growth mechanism of YIG crystal fibers using the laser heated pedestal growth method

Abstract

Yttrium iron garnet (YIG, Y 3Fe 5O 12) single-crystal fibers were grown by the laser heated pedestal growth (LHPG) method. Different compositions, with various Y 2O 3 and Fe 2O 3 ratios seeds were used. The microstructure and the compositional variation of the obtained crystals show that YIG single-crystal fibers could be directly grown at the stable freezing interface when the melt had a composition of 78–87 mol% Fe 2O 3. When the seed's Fe 2O 3 concentration was below 78 mol%, the yttrium orthoferrite (YFeO 3) would crystallize out until the composition of the melt increased along the liquidus curve until it needed a concentration of 78 mol% Fe 2O 3 or higher, whereupon YIG started to crystallize from the liquid. With the LHPG method, however, when Fe-rich ceramic rod used as a seed was employed to grow YIG crystal, the crystallographic orientation was indefinite. Therefore, YIG single-crystal fibers with the desired crystallographic orientation could only be obtained using a two-pass method. During the forward pass, YIG single crystal could be directly grown using a Fe-rich solvent, while during the backward pass, the crystallographic orientation of the grown crystal would be the same as that of the YIG seed.