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用剂量为8.2×1018/cm2的中子对6H-SiC晶体进行了辐照。采用X射线衍射仪、差示扫描量热仪测试6H-SiC晶体中辐照损伤。结果表明:中子辐照对6H-SiC样品产生了严重损伤,且辐照后的6H-SiC的比热容明显上升。对辐照样品进行了常温至1200℃的退火处理,退火后的辐照样品的比热容先随退火温度的升高而逐渐降低,1000℃时比热容到达最低值;当退火温度超过1000℃时晶体的比热容反而上升。运用从头算方法定性计算了晶体中间隙原子对比热容的影响。结果表明:晶体经中子辐照及退火后,其比热容发生变化的主要原因在于晶体中间隙原子的浓度的变化。辐照后的样品在超过1000℃退火时比热容的反常回升现象,极有可能与辐照前对晶体所作的在1000℃的预退火处理有关。
6H-SiC crystals were irradiated with neutrons at a dose of 8.2 × 10 18 / cm 2. Radiation damage in 6H-SiC crystals was measured by X-ray diffraction and differential scanning calorimetry. The results show that the neutron irradiation seriously damages the 6H-SiC samples, and the specific heat capacity of the irradiated 6H-SiC increases obviously. The irradiated samples were annealed at room temperature to 1200 ℃. The specific heat capacity of annealed samples firstly decreased with the increase of annealing temperature and reached the lowest value at 1000 ℃. When the annealing temperature was over 1000 ℃, Instead, the heat capacity increased. The ab initio method is used to qualitatively calculate the effect of the relative heat capacity of the interstitial atoms in the crystal. The results show that the main reason for the change of specific heat capacity of the crystal after neutron irradiation and annealing is the change of the concentration of interstitial atoms in the crystal. The abnormal recovery of specific heat capacity of irradiated samples when annealed above 1000 ° C is most likely related to the pre-annealing of the crystals at 1000 ° C prior to irradiation.