We investigate the electronic structure ofβ-uranium,which has five nonequivalent atomic sites in its unit cell,by means of the density functional theory plus Hubbard-U correction with U from linear response calculati...We investigate the electronic structure ofβ-uranium,which has five nonequivalent atomic sites in its unit cell,by means of the density functional theory plus Hubbard-U correction with U from linear response calculation.It is found that the 5f electronic correlations inβ-uranium are moderate.More interestingly,their strengths are site selective,depending on the local atomic environment of the present uranium atom.As a consequence,the occupation matrices and partial 5f density of states ofβ-uranium manifest site dependence.In addition,the complicate experimental structure ofβ-uranium could be well reproduced within this theoretical framework.展开更多
SF_6气体由于其优异的电气性能而广泛应用于电力行业,然而,由于其全球变暖潜能值极高,国内外学者在过去的几十年里对SF_6替代气体做了广泛研究,但由于它们都各有缺陷,故很难在实际生产中加以应用。文中以C_5F_(10)O/CO_2混合气体作为主...SF_6气体由于其优异的电气性能而广泛应用于电力行业,然而,由于其全球变暖潜能值极高,国内外学者在过去的几十年里对SF_6替代气体做了广泛研究,但由于它们都各有缺陷,故很难在实际生产中加以应用。文中以C_5F_(10)O/CO_2混合气体作为主要研究对象、以SF_6气体作为对照,研究了混合气体中C_5F_(10)O分压力分别为20 k Pa和40 k Pa、总压力为0.1~0.5 MPa时的工频耐压和雷电冲击(lightning impulse,LI)性能,并分析了其作为SF_6替代气体的可能性。实验结果表明,0.2 MPa的混合气体中混入20 k Pa和40 k Pa的C_5F_(10)O,可分别使混合气体的工频放电电压达到相同气压下SF_6气体的61.89%和81.99%。C_5F_(10)O分压力40 k Pa、总压力0.5 MPa的混合气体正、负极性雷电冲击放电电压分别是0.3 MPa时SF_6气体的88.9%和89.9%。因此,通过增加C_5F_(10)O的含量或提高混合气体的总压力,均可有效提高混合气体的绝缘性能,其中,前者更为有效。展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.22176181,11874329,11934020,and U1930121)the Foundation of the President of China Academy of Engineering Physics (Grant No.YZJJZQ2022011)the Foundation of Science and Technology on Surface Physics and Chemistry Laboratory (Grant No.WDZC202101)。
文摘We investigate the electronic structure ofβ-uranium,which has five nonequivalent atomic sites in its unit cell,by means of the density functional theory plus Hubbard-U correction with U from linear response calculation.It is found that the 5f electronic correlations inβ-uranium are moderate.More interestingly,their strengths are site selective,depending on the local atomic environment of the present uranium atom.As a consequence,the occupation matrices and partial 5f density of states ofβ-uranium manifest site dependence.In addition,the complicate experimental structure ofβ-uranium could be well reproduced within this theoretical framework.
文摘SF_6气体由于其优异的电气性能而广泛应用于电力行业,然而,由于其全球变暖潜能值极高,国内外学者在过去的几十年里对SF_6替代气体做了广泛研究,但由于它们都各有缺陷,故很难在实际生产中加以应用。文中以C_5F_(10)O/CO_2混合气体作为主要研究对象、以SF_6气体作为对照,研究了混合气体中C_5F_(10)O分压力分别为20 k Pa和40 k Pa、总压力为0.1~0.5 MPa时的工频耐压和雷电冲击(lightning impulse,LI)性能,并分析了其作为SF_6替代气体的可能性。实验结果表明,0.2 MPa的混合气体中混入20 k Pa和40 k Pa的C_5F_(10)O,可分别使混合气体的工频放电电压达到相同气压下SF_6气体的61.89%和81.99%。C_5F_(10)O分压力40 k Pa、总压力0.5 MPa的混合气体正、负极性雷电冲击放电电压分别是0.3 MPa时SF_6气体的88.9%和89.9%。因此,通过增加C_5F_(10)O的含量或提高混合气体的总压力,均可有效提高混合气体的绝缘性能,其中,前者更为有效。
