Unconventional Electronic Properties of Mg2Si Thermoelectrics Revealed by Fast-Neutron-Irradiation Doping

详细信息    查看全文

• 作者：Alexander E. Karkin ; Vladimir I. Voronin ; Natalia V. Morozova ; Sergey V. Ovsyannikov ; Ken-ichi Takarabe ; Yoshihisa Mori ; Shigeyuki Nakamura ; Vladimir V. Shchennikov
• 刊名：Journal of Physical Chemistry C
• 出版年：2016
• 出版时间：May 12, 2016
• 年：2016
• 卷：120
• 期：18
• 页码：9692-9701
• 全文大小：674K
• 年卷期：0
• ISSN：1932-7455

文摘

In this work, we systematically investigated the electrical resistivity, Hall, and magnetoresistance effects of Al-doped Mg₂Si thermoelectrics, irradiated with a fluence of fast neutrons and consequently isochronally annealed at moderate high temperatures up to 500 °C. We found that the fast-neutron bombardment itself only slightly modified the electronic properties. Meanwhile, a series of the postirradiation high-temperature anneals affected the properties dramatically. Thus, after annealing at temperatures of 275–325 °C, Mg₂Si:Al showed pronounced jumps in both the electrical resistivity and the Hall constant values by several orders of magnitude. This unexpected electronic transition corresponded to a significant variation in the carrier concentration. We proposed that this unusual electronic transition may be related to temperature-assisted chemical bonding of the radiation defects that can involve free charge carriers in the sample, thereby tuning dramatically its transport properties. We proposed a simple model for Mg₂Si:Al thermoelectrics, which links the chemical bonding of the interstitial Mg ions with the electronic properties of this material. This finding suggests a new avenue to tuning of electronic properties and unconventional electronic transitions in materials with a high concentration of defects.