An Anti CuO2-type Metal Hydride Square Net Structure in Ln2M2As2Hx (Ln=La or Sm, M=Ti, V, Cr, or Mn)†
This study was supported by the JSPS FIRST and the JST ACCEL projects. The neutron scattering experiment was approved by the Neutron Scattering Program Advisory Committee of IMSS, KEK (Proposal No. 2014S06). We are grateful to Dr. O. Fukunaga, Dr. Y. Muraba, and Dr. J. Bang (Tokyo Institute of Technology) for help with the high-pressure experiments. We also thank Dr. O. Jepsen and Dr. Y. Nohara (Max Planck Institute, Stuttgart, Germany) for providing the LMTO code.
Abstract
Using a high pressure technique and the strong donating nature of H−, a new series of tetragonal La2Fe2Se2O3-type layered mixed-anion arsenides, Ln2M2As2Hx, was synthesized (Ln=La or Sm, M=Ti, V, Cr, or Mn; x≈3). In these compounds, an unusual M2H square net, which has anti CuO2 square net structures accompanying two As3− ions, is sandwiched by (LaH)2 fluorite layers. Notably, strong metal–metal bonding with a distance of 2.80 Å was confirmed in La2Ti2As2H2.3, which has metallic properties. In fact, these compounds are situated near the boundary between salt-like ionic hydrides and transition-metal hydrides with metallic characters.
