金红石(TiO2)单晶体的生长研究

通过对比晶体在不同气氛中生长与退火的结果,研究了焰熔法生长金红石单晶体的工艺条件·结果表明:炉膛气氛是决定晶体能否形成的关键因素,在合适的气氛条件下,晶体易于生长,生长速度范围较宽,可以长成较大尺寸的单晶体,否则,依赖调整(增加或降低)生长速度,不能形成完整的晶体·炉膛气氛中的氧分压大于液固界面(即生长界面)处熔体的氧离解压是生长完整晶体的前提条件;晶体在退火过程中消除热应力,但更重要的是氧化反应,消除氧空位,在氧气氛中退火,可明显缩短退火时间,并能获得呈透明状,微有浅黄色(金红石本色)的金红石单晶体·

Study on Growth of Rutile (TiO2) Single Crystals

The processing conditions under which the rutile single crystal grows by way of flame fusion were studied comparing its growth and annealing results in different atmospheres. The results showed that the oven atmosphere is decisive to whether crystal could be formed or not, which may be controlled by the ratio of hydrogen to oxygen supplied in it. The crystal is easy to grow in a wide growth rate range to become a relatively big one if the oven atmosphere is suitable. It was revealed that no complete crystal can be obtained relying simply on adjusting (increasing or decreasing) the growth rate. The oven atmosphere in which the oxygen partial pressure is higher than oxygen's dissociation pressure at the liquid-solid interface is proved a prerequisite condition to form a complete crystal. The role of annealing is to relieve thermal stress formed in crystal growth but more important, it shall eliminate oxygen vacancies by oxidization reaction. The annealing time can be considerably shortened in an oxygen atmosphere in which a transparent light yellow rutile single crystal is obtained as its natural color.