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采用高纯(99.995%)、超细的金红石(TiO2)粉末为起始原料,用燃熔法制备了尺寸为30mm×50mm的金红石(TiO2)单晶体。讨论了生长气氛、生长速度、温度梯度在晶体生长中的作用,对比了晶体在空气中与在氧气中退火的结果,测定了晶体试样的摇摆曲线和透过率,并与商用晶体的透过率进行了比较。实验表明:生长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必要条件;在此条件下,能否生长为大尺寸晶体则取决于炉膛的轴向温度梯度;晶体在退火过程中可消除热应力,但退火更重要的作用是通过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;所制备的晶体完整性较好,透过率与商用晶体基本一致。
A rutile (TiO2) single crystal with size of 30mm × 50mm was prepared by burning fusion method using high purity (99.995%) and ultrafine rutile (TiO2) powder as starting material. The effects of growth atmosphere, growth rate and temperature gradient on the crystal growth were discussed. The results of annealing in air and oxygen in air were compared. The rocking curves and transmittance of the crystal were measured. The rates were compared. Experiments show that: the oxygen partial pressure in the growth atmosphere is greater than the liquid-solid interface (ie growth interface) at the melt oxygen dissociation pressure is the necessary conditions for the growth of complete crystal; in this condition, the ability to grow into large crystals will depend on the furnace Of the axial temperature gradient; the crystal in the annealing process to eliminate thermal stress, but the annealing is more important role in the elimination of oxygen vacancies by oxidation reaction, annealing in oxygen atmosphere, can significantly shorten the annealing time; the prepared crystal integrity is better , Transmittance and commercial crystals are basically the same.