中文摘要：

通过第一性原理与热力学结合的方法,研究了Ga,In等掺杂的CoSb3基方钴矿化合物中的复杂缺陷问题。详细计算了Ga,In在CoSb3中填充,Co,Sb位置替换以及填充-替换同时共存等缺陷的形成能。研究结果表明,缺陷形成能与费米能级、化学势等相关。Ga,In等在方钴矿中不是单纯的填充,而是填充和Sb位置替换同时共存的复杂缺陷。Ga掺杂以填充-替换比例2∶1的缺陷为主,而In掺杂,根据不同的条件可形成填充,替换,以及不同比例的填充替换复合缺陷,其中尤其以4∶2和2∶1最多。根据巨正则系宗,研究了Ga,In掺杂系统的载流子浓度和各缺陷的浓度。发现Ga,In掺杂的方钴矿由于填充和替换电荷的自补偿效应,其载流子浓度较低,尤其是Ga填充,具有类似本征半导体的低载流子浓度,且得到实验证实。In掺杂系统由于填充替换的比例偏离2∶1,填充位置的In比Ga的稍高一些,因此具有比Ga掺杂更高的载流子浓度。

英文摘要：

After the remediation of arsenic contamination in Yangzonghai Lake, a mass of arsenic deposited to the sediments combined with the floccunlant. The total arsenic concentrations in the sediments and overlying water were determined. Tessier continuous extraction method was used to analyze the speciation of arsenic in different sediment layers, based on which Hakanson＇s index and geoaccumulation index were used to evaluate the pollution status and stability of arsenic in sediments to make clear whether the environmental engineering which used flocculants to control arsenic pollution of lake have secondary pollution risk. The results shows that the arsenic content of surface sediment distributed unevenly in lakebed, and it decreased by the depth in vertical direction. The arsenic content of sediments would increase with time. The most of geoaccumulation pollution levels are 0, and the potential ecological risk up to I, which indicated that arsenic pollution of the sediment and its potential risk are low, but geoaccumulation pollution and its potential risk will increase as time went by. Since residual arsenic（14.12-18.38 mg/kg） had higher percentage（93.47%-97.30%）, arsenic in sediments was very stable, and not easy to leach out to cause secondary pollution.