Striations in YIG fibers grown by the laser-heated pedestal method

摘要

Yttrium iron garnet (YIG) single-crystal fibers of nominal composition Y_3Fe_5O_(12) were grown by the laser-heated pedestal growth technique, a miniaturized float-zone process. YIG fibers in diameters ranging from 100 to 740 μm were grown at various rates and conditions, and analyzed by X-ray diffraction, electron microprobe, IR-VIS spectroscopy, and light scattering tomography. Infrared transparent YIG fibers were grown at rates below 10 mm/h in air. The transparency of the fibers was more dependent on the growth rate than on the stability of the molten zone. Some striations and surface ridges containing a Fe-rich composition were observed at all growth rates. Light scattering tomography studies revealed the presence of inclusions in some YIG fibers. Their size, density, composition and distribution depended on the growth conditions and molten zone stability. At growth rates below 10 mm/h, these defects and also the iron-oxide inclusions, which act as IR scattering centers, were significantly reduced.