水晶 : 最近の水晶産業とオートクレーブ内対流の数値解析 : 酸化物(<特集>21世紀を担うバルク単結晶)

抄録

Demand for quartz-based electrical devices is growing year by year due to widespread use in the multimedia field, especially as crystal oscillators, in mobile cellular phones, in SAW applications, and in digital still cameras. There is increasing demand for larger crystals with fewer line-defect and reduced inclusion of foreign particles. The main requirements for an autoclave for growing quartz crystals are a size of over 600 mm diameter, and up to 2,500 kg capacity. Numerical simulation of natural convection in an au-toclave with a baffle is performed with the finite element method. When the length of the heated part on the autoclave wall becomes greater than 2% of the height of the autoclave with 60% baffle closure, circulating flows in the upper and lower sections of the autoclave oscillate periodically. As the Rayleigh number is increased, the frequency and the amplitude of the flow oscillation increase.