Unraveling nano-scale effects of topotactic reduction in LaNiO2 crystals

• Published in: APL materials 2024-09, Vol.12 (9), p.091119-091119-7
• Main Authors: Wu, Yu-Mi, Puphal, Pascal, Isobe, Masahiko, Keimer, Bernhard, Hepting, Matthias, Suyolcu, Y. Eren, van Aken, Peter A.
• Format: Article
• Language: English
• ISSN: 2166-532X; 2166-532X
• DOI: 10.1063/5.0227732

Infinite-layer nickelates stand as a promising frontier in the exploration of unconventional superconductivity. Their synthesis through topotactic oxygen reduction from the parent perovskite phase remains a complex and elusive process. This study delves into the nano-scale effects of the topotactic lattice transformation within LaNiO2 crystals. Leveraging high-resolution scanning transmission electron microscopy and spectroscopy, our investigations uncover a panorama of structural alterations, including grain boundaries and coherent twin boundaries, triggered by reduction-induced transformations. In addition, our analyses unveil the formation of an oxygen-rich disordered transition phase encircling impurities and pervading crystalline domains and the internal strain is accommodated by grain boundary formation. By unraveling these nano-scale effects, our findings provide insights into the microscopic intricacies of the topotactic reduction process elucidating the transition from the perovskite to the infinite-layer phase within nickelate bulk crystals.