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Nb-doped SrTiO_3 thermoelectric ceramics with different niobium concentrations,sintering temperatures and Sr-site vacancies are successfully prepared by high energy ball milling combined with carbon burial sintering.For fully understanding the effect of niobium doping on SrTiO_3,thermoelectric transport properties are systematically investigated in a temperature range from 300 K to 1100 K.The carrier mobility can be significantly enhanced,and the electrical conductivity is quadrupled,when the sintering temperature rises from 1673 K to 1773 K(beyond the eutectic temperature(1713 K) of SrTiO_3–TiO_2).The lattice vibration can be suppressed by the lattice distortion introduced by the doped niobium atoms.However,Sr-site vacancies compensate for the lattice distortion and increase the lattice thermal conductivity more or less.Finally,we achieve a maximum value of figure-of-merit z T of 0.21 at 1100 K for Sr Ti_(0.9)Nb_(0.1)O_3 ceramic sintered at1773 K. 相似文献
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采用Pekar变分法和幺正变换相结合的方法研究了各向异性量子点中束缚磁极化子的Rashba效应和Zeeman效应.通过理论推导,得到束缚磁极化子基态能量的表达式.讨论了极化子基态能量与横向有效受限长度、纵向有效受限长度、磁场回旋共振频率、库仑束缚势的关系.由于晶体结构反演非对称性和时间反演非对称性,极化子能量发生Rashba自旋轨道分裂和Zeeman分裂.在强、弱磁场下,分别讨论了Zeeman效应和Rashba效应在能量分裂中所占的主导地位.由于声子和杂质的存在,极化子比裸电子态更稳定. 相似文献
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