温梯法蓝宝石（Al2O3）晶体的脱碳去色退火研究

温度梯度法（TGT）生长的Al2O3晶体因石墨发热体在高温时的挥发和原料中过渡性金属离子的存在，晶体在不同部位呈现不同颜色，一般上部为浅红色，尾部为浅黄绿色，将TGT法生长的Al2O3晶体（Ф110×80mm^3）依次经过高温氧化气氛、高温还原气氛脱碳、去色退火实验，即“两步法”退火实验，晶体变成无色、透明，经测试，Al2O3晶体的完整性、光学透过率和光学均匀性均有显著提高。

The sapphire boulegrown by TGT is a bit colorful due to the volatilization of graphite heater at high temperature and absorptions of transitional metal ions in raw material. It is light red at the shoulder and little yellow at the bottle of the sapphire boule, respectively. The as grown sapphire boule (phi 110x80mm(3)) turns out colorless and transparent after being decolourized and decarbonized in air and hydrogen successively at high temperature. The quality, optical transmissivity and homogeneity of the sapphire boule have remarkably improved.