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Title: A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units

Here we carried out a detailed structural study of the family of rare earth molybdenum bronzes, and synthesized reduced ternary molybdates of composition LnMo 16O 44. Bond valence sum (BVS) calculations clearly show that the molybdenum ions in tetrahedral coordination are hexavalent while the electron count in the primitive unit cell is odd. Yet, measurements show that the phases are semiconductors. The temperature dependence of the magnetic susceptibility of samples containing several different rare earth elements was measured. These measurements verified the presence of a 6.5 K magnetic phase transition not arising from the rare earth constituent, but likely associated with the unique isolated ReO 3-type Mo 8O 36 structural subunits in this phase. To better understand the behavior of these materials, electronic structure calculations were performed within density functional theory. Results suggest a magnetic state in which these structural moieties have an internal ferromagnetic arrangement, with small ~1/8 μ B moments on each Mo. We suggest that the Mo 8O 36 units behave like pseudoatoms with spin 1/2 derived from a single hole distributed over the eight Mo atoms that are strongly hybridized with the O atoms of the subunit. Interestingly, while the compound is antiferromagnetic, our calculations suggestmore » that a field-stabilized ferromagnetic state, if achievable, will be a narrow band half-metal.« less
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [4] ;  [5]
  1. Montclair State Univ., Montclair, NJ (United States). Dept. of Chemistry
  2. Florida A&M University -Florida State University College of Engineering, Tallahassee, FL (United States). Dept. of Chemical and Biomedical Engineering; Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
  3. Florida State Univ., Tallahassee, FL (United States). National High Magnetic Field Lab. (MagLab)
  4. Florida A&M University -Florida State University College of Engineering, Tallahassee, FL (United States). Dept. of Chemical and Biomedical Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
  5. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Materials Science and Technology Division
Publication Date:
Grant/Contract Number:
AC05-00OR22725; SC0008832
Type:
Accepted Manuscript
Journal Name:
Journal of Solid State Chemistry
Additional Journal Information:
Journal Volume: 227; Journal Issue: C; Journal ID: ISSN 0022-4596
Publisher:
Elsevier
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Florida State Univ., Tallahassee, FL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Contributing Orgs:
Oak Ridge National Laboratory; Montclair State University
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; molybdenum bronzes; crystallographic structure; magnetism; Mo8O36 units; DFT calculations
OSTI Identifier:
1333511
Alternate Identifier(s):
OSTI ID: 1253042; OSTI ID: 1265478

Schneemeyer, L. F., Siegrist, T., Besara, T., Lundberg, M., Sun, J., and Singh, D. J.. A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units. United States: N. p., Web. doi:10.1016/j.jssc.2015.03.028.
Schneemeyer, L. F., Siegrist, T., Besara, T., Lundberg, M., Sun, J., & Singh, D. J.. A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units. United States. doi:10.1016/j.jssc.2015.03.028.
Schneemeyer, L. F., Siegrist, T., Besara, T., Lundberg, M., Sun, J., and Singh, D. J.. 2015. "A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units". United States. doi:10.1016/j.jssc.2015.03.028. https://www.osti.gov/servlets/purl/1333511.
@article{osti_1333511,
title = {A family of rare earth molybdenum bronzes: Oxides consisting of periodic arrays of interacting magnetic units},
author = {Schneemeyer, L. F. and Siegrist, T. and Besara, T. and Lundberg, M. and Sun, J. and Singh, D. J.},
abstractNote = {Here we carried out a detailed structural study of the family of rare earth molybdenum bronzes, and synthesized reduced ternary molybdates of composition LnMo16O44. Bond valence sum (BVS) calculations clearly show that the molybdenum ions in tetrahedral coordination are hexavalent while the electron count in the primitive unit cell is odd. Yet, measurements show that the phases are semiconductors. The temperature dependence of the magnetic susceptibility of samples containing several different rare earth elements was measured. These measurements verified the presence of a 6.5 K magnetic phase transition not arising from the rare earth constituent, but likely associated with the unique isolated ReO3-type Mo8O36 structural subunits in this phase. To better understand the behavior of these materials, electronic structure calculations were performed within density functional theory. Results suggest a magnetic state in which these structural moieties have an internal ferromagnetic arrangement, with small ~1/8 μB moments on each Mo. We suggest that the Mo8O36 units behave like pseudoatoms with spin 1/2 derived from a single hole distributed over the eight Mo atoms that are strongly hybridized with the O atoms of the subunit. Interestingly, while the compound is antiferromagnetic, our calculations suggest that a field-stabilized ferromagnetic state, if achievable, will be a narrow band half-metal.},
doi = {10.1016/j.jssc.2015.03.028},
journal = {Journal of Solid State Chemistry},
number = C,
volume = 227,
place = {United States},
year = {2015},
month = {4}
}