Experimental and Theoretical Research for Electrical Properties of Quasicrystals

对Al-Pd-Re系中单一二十面体相的形成范围进行了广泛的研究。首次在Al-Pd-Re系中成功地获得了电阻率随组分的变化规律。为了解释电阻率随组分变化的原因，对合金的1/2(311111)超晶格峰和(211111)五重峰的准晶格常数和强度进行了详细的研究，发现准晶格常数的增大和与密排结构的偏离与合金的电阻率的增大相一致。测量了不同成分和不同电阻率值的Al-Pd-Re绝缘准晶的电阻率、霍尔系数和磁阻随温度的变化关系，以揭示绝缘Al-Pd-Re准晶的导电机制。从能带方案的角度讨论了传导机制。在考虑有效电子和空穴温度变化的双带模型的基础上，分析了高温区(&gt；20K)的电导率和霍尔系数随温度的变化。在弱局域化和电子-电子相互作用理论的框架下，分析了低温区(~lt；20K)的电导和磁阻数据。

The formation range of single icosahedral phase in the Al-Pd-Re system has been extensively studied based on a large variety of alloys with slitely different compositions. Composition dependence of electrical resistivity was successfully obtained for the first time in the Al-Pd-Re system. In order to elucidate the origin of the composition dependence of resistivity, the quasilattice constant and the intensities of the 1/2(311111)superlattice peak and the(211111)five fold peak have been closely investigated and it has been found that an increase of the quasilattice constant and deviation from closely packed structures coincide with an increase of the resistivity of alloys. Measurements of the temperature dependences of the resistivity, Hall coefficient and magnetoresistance on samples with different compositions and different resistivity values have been presented to shed light on the conduction mechanism in the insulating Al-Pd-Re quasicrystal. Discussions on the conduction mechanism are presented in terms of the band scheme. An analysis on the temperature dependence of conductivity and Hall coefficient in high temperature region(>20K)are performed based on the two band model which takes account of the temperature variation of the effective electrons and holes. The conductivity and magnetoresistance data in low temperature region(<20K)are analyzed in the framework of the weak localization and the electron-electron interaction theories.