Unraveling atomic positions in an oxide spinel with two Jahn-Teller ions: Local structure investigation of CuMn2O4

Daniel P. Shoemaker, Jun Li, Ram Seshadri

Research output: Contribution to journalArticlepeer-review

Abstract

At first sight, the quenched tetragonal spinel CuMn2O 4 can be formulated with Cu2+ and Mn3+, implying that the tetrahedral site is Jahn-Teller (JT)-active Cu2+ and the octahedral site is JT-active Mn3+. High-resolution, high-momentum-transfer neutron scattering analysis suggests that the sample has ∼30% inversion: Mn on the tetrahedral Cu site with compensating Cu on the octahedral site. Reverse Monte Carlo (RMC) analysis of the pair distribution function allows details of metal-oxygen connectivity to be probed in a manner that is significantly on the local rather than the average scale. Bond valence analysis of the RMC supercell reveals that both JT ions disproportionate to higher and lower valence states as a means of avoiding their JT tendency, particularly on the tetrahedral site. The occurrence of Cu3+ in particular is suggested for the first time and is supported by X-ray photoelectron spectroscopy data. The bimodal distribution of O-Cu-O bond angles at the tetrahedral site (distinct from what is seen for O-Mn-O bond angles) further reveals a hidden distinction between sites previously considered to be equivalent. Application of total scattering techniques originally developed for highly disordered materials permits the examination of nanoscale crystalline structure with elemental specificity that is not available in traditional reciprocal-space analysis.

Original languageEnglish (US)
Pages (from-to)11450-11457
Number of pages8
JournalJournal of the American Chemical Society
Volume131
Issue number32
DOIs
StatePublished - Aug 19 2009
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Fingerprint

Dive into the research topics of 'Unraveling atomic positions in an oxide spinel with two Jahn-Teller ions: Local structure investigation of CuMn2O4'. Together they form a unique fingerprint.

Cite this