Abstract
To simulate the evolution of amorphous Mg2SiO4 (forsterite) to the forsterite crystals, we need amorphous particles in the experiment as the starting materials. Although amorphous forsterite has been synthesized from vapor phase, these particles are too small (< 1 μm) to be investigated by optical method. Therefore, we have applied a gas jet levitator method to solve this problem. A gas jet levitator method is useful to avoid heterogeneous nucleation during cooling process and thus melt droplets were very stable at large supercooling (> 1000 K).The starting materials were synthesized forsterite spherules (~ 2 mm), which was set at the top of the nozzle (1 mm in diameter) of the gas jet levitator and then levitated by introducing Ar gas. The spherule was melted by CO2 laser (100 W) irradiation. The melt temperature was measured with a pyrometer.The experimental results show that amorphous formation of forsterite took place at ~ 1000 K with a larger cooling rate than 300K/s, which was much smaller cooling rate as obtained by Tangeman et al. (2001), 700 K/s. While, enstatite melts with higher SiO2 content formed only amorphous material at any conditions.
