A high-valent palladate, La3Pd2NaO9, has been synthesized for the first time. Single crystals with dimensions of 20 μm on edge were successfully grown using the flux method at 420 oC and 70 bar oxygen pressure. Energy dispersive spectroscopy (EDS) and inductively coupled plasma mass spectroscopy (ICP) measurements show that the atomic ratio of La: (Pd+Na) is 3: 3 and Pd: Na is 2: 1. X-ray photoelectron spectroscopy (XPS) measurements show that the oxidation state of Pd is dominated by +4. Synchrotron X-ray single-crystal diffraction measurements revealed that this material crystallizes in the monoclinic P21/c space group with charge ordering of Na and Pd. Real-space imaging via scanning transmission electron microscopy (STEM) confirmed the crystal structure and revealed excellent sample homogeneity. Electrical resistivity measurements show an insulating behavior. Magnetic measurements show an unexpected paramagnetic behavior, which probably originate from a small fraction of high-spin Pd2+ evidenced by XPS. The successful growth of La3Pd2NaO9 single crystals with a high-valent oxidation state of Pd offers an approach for exploring interesting palladates, including potential bilayer Ruddlesden-Popper palladates analogous to the high temperature superconducting La3Ni2O7.
@article{arxiv.2506.15966,
title = {$La_3Pd_2NaO_9$: A High-Valent Insulating Palladate},
author = {Qingqing Yang and Ning Guo and Tieyan Chang and Zheng Guo and Xiaoli Wang and Chuanyan Fan and Chao Liu and Lu Han and Feiyu Li and Tao He and Qiang Zheng and Yu-Sheng Chen and Junjie Zhang},
journal= {arXiv preprint arXiv:2506.15966},
year = {2025}
}
Comments
19 pages, 8 figures. This document is the unedited author's version of a Submitted Work that was subsequently accepted for publication in Inorganic Chemistry, copyright American Chemical Society after peer review. To access the final edited and published work, a link will be provided soon