Synthesis and Physical Properties of Layered Copper Oxytellurides Sr2TMCu2Te2O2 (TM = Mn, Co, Zn)
Synthesis and Physical Properties of Layered Copper Oxytellurides Sr2TMCu2Te2O2 (TM = Mn, Co, Zn)
复制标题
层状氧碲化铜Sr2TMCu2Te2O2 (TM = Mn, Co, Zn)的合成及物理性能
DOI：
10.1039/c8tc04506b
复制
发表时间：
2018
影响因子：
6.4
通讯作者：
Hiraku Ogino
中科院分区：
文献类型：
--
作者：
Dongjoon Song;Gabin Gu?lou;Takao Mori;Masayuki Ochi;Kazuhiko Kuroki;Hiroshi Fujihisa;Yoshito Gotoh;Yuki Iwasa;Hiroshi Eisaki;Hiraku Ogino
合成了一系列过渡金属（TM = Mn，Co，Zn）掺杂的层状铜碲氧化合物Sr_2TMCu_2Te_2O_2。这些化合物是具有交替堆叠的反萤石Cu2Te2和类钙钛矿TM氧化物层的第一实例。由于Te的离子半径比Se和S的离子半径长，它们表现出比同构硫化物和硒化物更大的晶格参数。作为代表的Zn化合物的第一原理能带结构计算揭示了1.7eV的半导体直接带隙，并且Co化合物在漫反射率测量结果中示出了可比较的带隙。从热电性能研究中，我们确定了Co化合物在770 K时的功率因数为1.70 μW m−1 K−2，品质因数ZT为1.045，这鼓励通过应用各种增强方法进一步改善热电响应。在磁性方面，在Co和Mn化合物中观察到反铁磁有序的签名。目前的结果不仅突出了系统的结构灵活性，以调整的物理性能，但也表明，阻挡层的更换可以是一种新的方式来提高层状铜氧硫族化合物的热电性能。
We synthesized a new series of layered copper oxytellurides Sr2TMCu2Te2O2 with variation in transition metal (TM = Mn, Co, and Zn) elements. These compounds are the first example having alternately stacked anti-fluorite Cu2Te2 and perovskite-like TM-oxide layers. Owing to the longer ionic radius of Te compared to those of Se and S, they exhibit larger lattice parameters than isostructural sulfides and selenides. First principles band structure calculation for the Zn compound as a representative reveals a semiconducting direct band gap of ∼1.7 eV and the Co compound shows a comparable band gap in the diffuse reflectance measurement result. From the thermoelectric property study, we determined a power factor of ∼70 μW m−1 K−2 and a figure of merit ZT of ∼0.045 at 770 K for the Co compound, which encourages further improvement in thermoelectric response by applying various enhancement methods. In terms of the magnetic properties, a signature of antiferromagnetic order is observed in the Co and Mn compounds. The present results not only highlight the structural flexibility of the system to tune the physical properties but also suggest that the replacement of the blocking layer can be a new way to improve the thermoelectric performance of layered copper oxychalcogenides.