GROWTH OF (FEXMG1-X)(2)SIO4 SINGLE-CRYSTALS BY THE DOUBLE-PASS FLOATING-ZONE METHOD

Good quality olivine single crystals, (FexMg1-x)(2)SiO4, have been suc cessfully grown by the floating zone method using an image furnace. Th e double pass floating zone method was utilized to grow crystals with uniform composition along the growth axis. Chemical analyses by electr on microprobe confirmed that the crystals were homogeneous in composit ion along the growth direction over the entire length of the boule. Th e primary crystal defects observed were bubbles. Precipitates, such as iron oxide and silica-rich phases were only occasionally found in iro n-rich olivine crystals. An after-heater, either active or passive, wa s placed just below the freezing interface to control the interface sh ape and reduce the thermal gradient, enabling the growth of crack-free single crystals.