氧和铝在氧化铝中的自扩散参数评估

Assessment of Self-diffusion Parameters in Alumina Single Crystals

评估了氧和铝在Ａｌ２Ｏ３中的自扩散参数，分析了其扩散机理．得出：（１）在１７７０～２１００Ｋ 温度范围内，氧分压不超过１．０×１０５Ｐａ时，杂质总含量为３０×１０－６～５００×１０－６，Ｍｇ，Ｔｉ含量低于３０× １０－６的未掺杂Ａｌ２Ｏ３单晶中，氧的自扩散系数与温度的关系式，氧分压和扩散方向对该扩散系数 值影响不明显．（２）在１９４３～２１７８Ｋ范围，多晶Ａｌ２Ｏ３中铝的自扩散系数在１０－１５到１０－１４ｍ２／ｓ之间， 扩散活化能为 ４７７ ｋＪ／ｍｏｌ．（３）单晶Ａｌ２Ｏ３中主要杂质为ＴｉＯ２和 ＭｇＯ，掺Ｔｉ将降低氧的自扩散系 数，增加铝的自扩散系数；掺Ｍｇ使氧的自扩散系数略有增加；其他杂质对氧和铝在Ａｌ２Ｏ３中的 扩散系数影响不大．（４）氧和铝均通过空位扩散．

The oxygen ion and aluminum ion self-diffusion parameters in alumina single ciystals were reviewed and assessed, and the diffusion mechanism was analyzed. The results suggest that: (1) In the tempera-ture range from 1770 to 2100 K, oxygen self-diffusion coefficient in single crystal of undoped A1203 with im-purities level of 30xl06,~,500xl06 (the content of Mg as well as Ti should be less than 30x106), under an oxygen partial pressure less than 1 .Ox 10~ Pa, the formula of self-diffusion confficient and temperature can be obtained. The diffusivity of the oxygen self-diffusion in single crystal of undoped Al203 is insensitive to the variation of oxygen partial pressure and the diffusion direction. (2) In the temperature range from 1943 to 2178 K, aluminum ion diffusion coefficient in polycrystalline aluminum oxide is about 10-15 to 10-14 m2/s, the acti-vation energy is about 477 kJ/mol. (3) The major impurity species in A1203 single crystal are Ti02 and MgO. Doping with titania will decrease oxygen self-diffusivity and doping with magnesium will increase oxygen self-diffusivity. Since the contents of other impurity species dissolved in A1203 are low, the influence of their presence on the oxygen self-diffusivity is not of significance. (4) The diffusion of aluminum and oxygen ions occurs through a vacancy mechanism.