Thermodynamic-driven selective synthesis and phase transformation of Sr-doped neodymium nickelate Ruddlesden–Popper epitaxial films
Thermodynamic-driven selective synthesis and phase transformation of Sr-doped neodymium nickelate Ruddlesden–Popper epitaxial films
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DOI：
10.1063/5.0174045
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发表时间：
2023-11
期刊：
影响因子：
6.1
通讯作者：
Xiao Gao;Junhua Liu;Yaoyao Ji;Long Wei;Wen Xiao;Shilin Hu;Lin Li;Yulin Gan;Kai Chen;Zhaoliang Liao
中科院分区：
文献类型：
--
作者：
Xiao Gao;Junhua Liu;Yaoyao Ji;Long Wei;Wen Xiao;Shilin Hu;Lin Li;Yulin Gan;Kai Chen;Zhaoliang Liao
最近发现的高压下La3Ni2O7单晶80k超导特征，为用Ruddlesden-Popper镍酸盐实现高温超导体提供了线索。在这里，我们演示了通过控制生长温度，在一个陶瓷Nd0.8Sr0.2 nio3靶材上实现Nd0.8Sr0.2 nio3钙钛矿膜和（Nd0.8Sr0.2）2NiO4 rudlesden - popper膜的选择性制备。结果进一步表明，在1000℃的空气中退火后，生长的Nd0.8Sr0.2 nio3薄膜可以转变为（Nd0.8Sr0.2）2NiO4。发现Nd0.8Sr0.2 nio3和（Nd0.8Sr0.2）2NiO4薄膜分别具有金属性和绝缘性。x射线光电子能谱结果表明，生长的（Nd0.8Sr0.2）2NiO4薄膜中含有NiO杂质，可以通过高温退火去除。x射线吸收光谱测量表明，（Nd0.8Sr0.2）2NiO4薄膜中Ni - o的价态较低，杂化减弱。衬底晶格应变强烈影响Nd0.8Sr0.2 nio3的稳定性和（Nd0.8Sr0.2）2NiO4的形成。这些结果表明热力学原理在镍酸盐薄膜的生长和退火过程中起着重要的作用。这些发现为制备Ruddlesden-Popper系列镍酸盐薄膜提供了途径，并为镍酸盐超导性的发展提供了一定的动力。
Recent discovery of the signature of 80 K superconductivity in La3Ni2O7 single crystals under high pressure sheds the light on the realization of high temperature superconductors from Ruddlesden–Popper nickelates. Here, we demonstrated the realization of selective fabrication of Nd0.8Sr0.2NiO3 perovskite films and (Nd0.8Sr0.2)2NiO4 Ruddlesden–Popper films from one ceramic Nd0.8Sr0.2NiO3 target simply by controlling the growth temperature. Our results further show that the as-grown Nd0.8Sr0.2NiO3 films can be transformed to (Nd0.8Sr0.2)2NiO4 by annealing in air at 1000 °C. Nd0.8Sr0.2NiO3 and (Nd0.8Sr0.2)2NiO4 films were found to be metallic and insulating, respectively. X-ray photoelectron spectroscopy results reveal that the as-grown (Nd0.8Sr0.2)2NiO4 films contained NiO impurity, which can be removed by high temperature annealing. X-ray absorption spectroscopy measurements indicate a lower Ni valence state and weakened hybridization between Ni–O in (Nd0.8Sr0.2)2NiO4 films. Substrate lattice strain strongly affects the stability of Nd0.8Sr0.2NiO3 and the formation of (Nd0.8Sr0.2)2NiO4. These results suggest an important role of thermodynamic principles in the growth and post-annealing of nickelate films. These findings provide an approach to obtain Ruddlesden–Popper series nickelate films and offer certain impetuses to the development of nickelate superconductivity.