ZrTe5、HfTe5的单晶生长及输运性质研究

摘要从实验上系统研究了过渡金属五碲化物HfTe5、ZrTe5的晶体生长及输运性质，并探索了外加磁场对材料输运性质的影响。通过化学气相输运法制备了HfTe5、ZrTe5的单晶，并利用X射线衍射仪(XRD)、振动样品磁强计(VSM)、物理性质综合测量系统(PPMS)等测试手段对材料的晶体结构、输运性质等进行表征和分析。研究结果表明：过渡金属五碲化物HfTe5、ZrTe5是一类有着奇异的输运性质的材料体系，其电阻率对温度的依赖关系曲线在特定温度下出现反常峰值，且热电势在相应温度处发生过零转变。外加磁场对材料电阻率的反常峰值和低温区的绝对热电势数值均有不同程度的增强。因此，实验上可以通过控制外加磁场的大小和方向对HfTe5、ZrTe5的热电性能进行调控。30085
关键词过渡金属五碲化物低文半金属反常输运性质热电制冷
毕业论文设计说明书外文摘要
Title     The study on the growth and transport properties of single crystals HfTe5 and ZrTe5
Abstract
The crystal growth of transition-metal pentatellurides HfTe5 and ZrTe5 has been performed and their transport properties have been measured as a function of temperature and applied magnetic field. Single crystals of HfTe5 and ZrTe5 were grown by means of chemical vapor phase transport reactions and several measurement methods including XRD, VSM and PPMS were used to make some analysis and characterization on the crystal structure and transport properties. The results showed that at zero magnetic field the transition-metal pentatellurides HfTe5 and ZrTe5 are such systems with many novel transport behaviors, which exhibit a peak in their resistivity as a function of temperature and a zero-crossing of thermoelectric power at the same temperature. The application of a transverse magnetic field to the current has a profound effect on the resistivity peak and absolute thermoelectric power in these materials. So to some extent it is possible to optimize the thermoelectric properties of HfTe5 and ZrTe5 with different applied magnetic field.
Keywords transition-metal pentatellurides low-dimensional semimetal
   anomalous transport properties    thermoelectric refrigeration
目   次
1 绪论    1
1.1 引言    1
1.2 电荷密度波（CDW）简介    2
1.3 过渡金属五碲化物HfTe5、ZrTe5的研究进展    4
1.3.1 HfTe5、ZrTe5的合成与晶体结构    4
1.3.2 HfTe5、ZrTe5的反常物理性质    6
1.3.3 HfTe5、ZrTe5的热电应用探索    11
1.4 本文的主要研究工作    15
2 HfTe5、ZrTe5的样品制备及结构表征    16
2.1 引言    16
2.2 实验细节    17
2.3 实验结果及讨论    17
3 HfTe5、ZrTe5单晶样品相关输运性质研究    22
3.1 电阻率测量    22
3.1.1 引言    22
3.1.2实验细节    22
3.1.3实验结果及讨论    24
3.2 磁化率测量    25
3.2.1 引言    25
3.2.2实验细节    26
3.2.3实验结果及讨论    26
3.3 热电势测量    27
3.3.1引言    27
3.3.2实验细节    28
3.3.3实验结果及讨论    29
3.4 本章小结    30
结论    32
致谢    33 ZrTe5、HfTe5的单晶生长及输运性质研究:http://www.youerw.com/wuli/lunwen_25620.html