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在4d过渡族金属氧化物AMoO3 (A = Ca, Sr, Ba)中, BaMoO3是唯一没有外延薄膜相关研究报导的材料. 本文以BaMoO3多晶陶瓷为靶材, 利用脉冲激光沉积技术得到了高质量的BaMoO3和BaMoO4外延薄膜; 分析了氧分压在薄膜生长中的作用, 发现BaMoO3的外延生长对氧分压极为敏感. 通过氧分压调制实验, 在SrTiO3 (111)衬底上发现了一种BaMoO3参与的自组装超晶格结构, 对其进行了结构表征和初步分析, 并从脉冲激光沉积制备钙钛矿薄膜的动力学角度对该结构的形成进行了讨论; 最后对本系列外延膜进行了电输运性质的表征, 结果显示在SrTiO3 (001)衬底上的外延BaMoO3薄膜有着更好的导电性.Transition metal oxides have been a research hotspot for basic scientific research and frontier applications. Owing to the presence of d
electrons and strong electron correlation, a wealth of physical phenomena emerges in the transition metal oxide family. In particular, extremely fruitful research progress is achieved in a 3d orbital elemental system. In comparison, the 4d transition metal oxides need more attention. Molybdate has excellent optical and electrical properties. Among AMoO3 (A = Ca, Sr, Ba), only BaMoO3 has not been reported for epitaxial films to date. In this work, high-quality epitaxial films of BaMoO3 and BaMoO4 are prepared by using the pulsed laser deposition. We conduct the oxygen partial pressure modulation experiments and the results show that the growth of BaMoO3 is sensitive to oxygen partial pressure. Also, BaMoO3 has a geometrically similar lattice structure to BaMoO4, and there exists epitaxial competition between BaMoO3 and BaMoO4. These two points make the preparation of epitaxial BaMoO3 films more challenging. The key to the preparation of epitaxial BaMoO3 thin films is the reduced laser target material, high vacuum environment, and ultra-low oxygen partial pressure. The epitaxy competition can be avoided by using the SrTiO3 (111) substrate. We conduct oxygen partial pressure modulation experiments on a narrow scale and reveal a self-assembled superlattice of epitaxial BaMoO3 film on a SrTiO3(111) substrate. Both the satellite peaks in the XRD pattern and the HRTEM results indicate the superlattice period of about 7.04 Å. The oxygen partial pressure is the only parameter that regulates this phenomenon, so we presume that the essence of the self-assembled superlattice is periodic oxygen-induced lattice defects. Finally, electrical transport characterization experiments are conducted on representative BaMoO3 films. The \rho \text- T curve measurements and fitting results show that the epitaxial BaMoO3 films on SrTiO3(001) substrates have better conductivities. The electrical transport properties of BaMoO3 films grown on SrTiO3(111) substrates are dominated by electron-phonon scattering, and BaMoO3 films grown on SrTiO3(001) substrate have stronger electron-electron scattering interactions. The resistivity of the self-assembled superlattice BaMoO3 films is relatively high and electron-electron scattering plays an important role in determining the electrical transport property.-
Keywords:
- pulsed laser deposition /
- BaMoO3 /
- BaMoO4 /
- epitaxial thin films
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中国物理学会期刊
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