Synthesis of rhombohedral LaCuO3 thin films using the oxidation effect of NaClO solution
Synthesis of rhombohedral LaCuO3 thin films using the oxidation effect of NaClO solution
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利用 NaClO 溶液氧化作用合成菱形 LaCuO3 薄膜
DOI：
10.1039/d1dt03984a
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发表时间：
2022
影响因子：
4
通讯作者：
S. Asanuma
中科院分区：
文献类型：
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作者：
S. Asanuma
LaCuO3是最基本的铜酸盐钙钛矿块体之一，具有与铜酸盐高温超导体相似的结构。因此，有人认为对LaCuO3的研究是阐明铜酸盐高温超导机理的线索之一。然而，由于需要高压高温（HPHT）方法，合成块状LaCuO3很困难，因此迄今为止对LaCuO3的研究还不够。在本文中，我报告了利用 NaClO 溶液的氧化作用，不使用 HPHT 方法成功合成了菱形 LaCuO3 薄膜。 LaCuO3−δ 薄膜在 80 °C 的 NaClO 溶液中氧化 72 小时后的横截面的纳米束电子衍射图表明了菱形 LaCuO3 的形成。由于很难直接测量菱形 LaCuO3 薄膜中的氧缺陷量，因此尚未直接测量。然而，考虑到氧缺陷的数量和块体LaCuO3−δ的对称性之间的关系，这些菱形LaCuO3薄膜被认为非常接近化学计量组成。薄膜电阻的温度依赖性表明菱形 LaCuO3 是绝缘体。结合以往对LaCuO3化学计量第一性原理计算的研究以及本研究，推测接近化学计量组成的菱形LaCuO3是莫特绝缘体。
LaCuO3 is one of the most fundamental cuprate perovskite blocks and has a similar structure to the cuprate high-temperature superconductor. Therefore, some consider that a study on LaCuO3 is one of the clues to clarify the mechanism of cuprate high-temperature superconductivity. However, since the synthesis of bulk LaCuO3 is difficult due to the need for the high-pressure and high-temperature (HPHT) method, not enough research on LaCuO3 has been done so far. In this paper, I report the successful synthesis of rhombohedral LaCuO3 thin films using the oxidation effect of NaClO solution without using the HPHT method. The nanobeam electron diffraction pattern of the cross-section of LaCuO3−δ thin film oxidized in NaClO solution at 80 °C for 72 hours demonstrates the formation of rhombohedral LaCuO3. The amount of oxygen defects in the rhombohedral LaCuO3 thin films has not been measured directly because it is difficult to do so. However, considering the relationship between the amount of oxygen defects and the symmetry of bulk LaCuO3−δ, these rhombohedral LaCuO3 thin films are considered to be very close to the stoichiometric composition. The temperature dependence of the resistance of the thin films indicates that rhombohedral LaCuO3 is an insulator. Considering the previous studies on the first-principles calculation of stoichiometric LaCuO3 and this study, the rhombohedral LaCuO3 close to the stoichiometric composition is presumed to be a Mott insulator.