Structure and magnetism of La<sub><i>x</i></sub>Sr<sub>2−<i>x</i></sub>Co<sub>0.5</sub>Ir<sub>0.5</sub>O<sub>4−<i>y</i></sub>H<sub><i>y</i></sub> (0 < <i>x</i> < 1) iridium-containing oxyhydride phases
Ruddlesden-Popper oxide phases in the La<sub><i>x</i></sub>Sr<sub>2-<i>x</i></sub>Co<sub>0.5</sub>Ir<sub>0.5</sub>O<sub>4</sub> (0 < <i>x</i> < 1) solid solution can be converted to the corresponding La<sub><i>x</i></sub>Sr<sub>2-<i>x</i></sub>Co<sub>0.5</sub>Ir<sub>0.5</sub>O<sub>4-<i>y</i></sub>H<sub><i>y</i></sub> oxyhydride phases, by topochemical reaction with LiH, in which the hydride ions are substituted exclusively onto the equatorial anion sites of the host framework. Analysis reveals that oxyhydride phases in the range 0.5 < <i>x</i> < 1 adopt La<sub><i>x</i></sub>Sr<sub>2-<i>x</i></sub>Co<sub>0.5</sub>Ir<sub>0.5</sub>O<sub>2+<i>x</i></sub>H<sub>2-<i>x</i></sub> compositions which maintain a constant Co<sup>1+</sup>, Ir<sup>3+</sup> oxidation-state combination (confirmed by Co K-edge XANES data), with the presence of low-spin d<sup>6</sup> Ir<sup>3+</sup> being consistent with the covalent stabilization of the metastable oxyhydride phases <i>via</i> strong Ir-H σ-bonds. Phases at the lanthanum-poor end of the solid solution (<i>x</i> < 0.5) adopt La<sub><i>x</i></sub>Sr<sub>2-<i>x</i></sub>Co<sub>0.5</sub>Ir<sub>0.5</sub>O<sub>4-<i>y</i></sub>H<sub><i>y</i></sub> compositions with lower hydride concentrations (<i>y</i> < 1.5). Magnetisation and μSR data indicate that all the La<sub><i>x</i></sub>Sr<sub>2-<i>x</i></sub>Co<sub>0.5</sub>Ir<sub>0.5</sub>O<sub>4-<i>y</i></sub>H<sub><i>y</i></sub> oxyhydride phases exhibit strong magnetic frustration, attributed to the large-scale cation and anion disorder, and resulting in glassy magnetic behaviour at low temperature.
Authors
- Michael A. Hayward (ORCID: https://orcid.org/0000-0002-6248-2063)
- Ronald I. Smith (ORCID: https://orcid.org/0000-0002-4990-1307)
- J. E. Murrell
- B. M. Huddart (ORCID: https://orcid.org/0000-0001-8584-105X)
- Stephen J. Blundell (ORCID: https://orcid.org/0000-0002-3426-0834)
- Romain Wernert (ORCID: https://orcid.org/0000-0002-5073-4008)
- Hank C. H. Wu
Institutions
- Rutherford Appleton Laboratory (GB)
- University of Oxford (GB)
Publication Details
- Journal
- Dalton Transactions
- Published
- 2025-01-01
- DOI
- https://doi.org/10.1039/d5dt00979k
- Primary Topic
- Advanced Condensed Matter Physics
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Diamond Light Source
- Government of the United Kingdom
- UK Research and Innovation
- HORIZON EUROPE Framework Programme
- Engineering and Physical Sciences Research Council
- Science and Technology Facilities Council