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Synthesis, Structure, and Properties of the Layered Oxyselenide Ba2CuO2Cu2Se2

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journal contribution
posted on 09.04.2018, 12:26 by Wenmin Li, Zhaoming Fu, Xiancheng Wang, Jun Zhang, Min Liu, Jianfa Zhao, Meiling Jin, Guoqiang Zhao, Guangyang Dai, Zheng Deng, Sijia Zhang, Shaomin Feng, Zhiwei Hu, Qingzhen Huang, Hongji Lin, Chien-Te Chen, Yifeng Yang, Changqing Jin
A new layered oxyselenide, Ba2CuO2Cu2Se2, was synthesized under high-pressure and high-temperature conditions and was characterized via structural, magnetic, and transport measurements. It crystallizes into space group I4/mmm and consists of a square lattice of [CuO2] planes and antifluorite-type [Cu2Se2] layers, which are alternately stacked along the c axis. The lattice parameters are obtained as a = b = 4.0885 Å and c = 19.6887 Å. The Cu–O bond length is given by half of the lattice constant a, i.e., 2.0443 Å. Ba2CuO2Cu2Se2 is a semiconductor with a resistivity of ∼18 mΩ·cm at room temperature. No magnetic transition was found in the measured temperature range, and the Curie–Weiss temperature was obtained as −0.2 K, suggesting a very weak exchange interaction. The DFT+Ueff calculation demonstrates that the band gap is about 0.2 eV for the supposed antiferromagnetic order, and the density of state near the top of the valence band is mainly contributed from the Se 4p electrons.