Neutron and synchroton X-ray diffraction study of the structures and dehydration behaviors of ramsdellite and "groutellite"

Jeffrey E. Post, Peter J. Heaney

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

The crystal structure of ramsdellite, MnO2, was refined using time-of-flight powder neutron diffraction data and the Rietveld method in order to assess the effects of reduction in cathodic battery materials. For the first time, we present a refined structure for "groutellite," a heretofore poorly characterized phase with ideal formula (Mn0.5 4+Mn0.5 3+ O1.5(OH)0.5. "Groutellite" is generated synthetically as an intermediate compound during the reduction of ramsdellite to groutite (MnOOH), and it also occurs as an intergrowth in certain natural specimens of ramsdellite. The Jahn-Teller distortions in "groutellite" are confined to the a-c plane, and they result in a 6.8% unit-cell volume increase relative to ramsdellite. The Mn-O bond lengths refined for "groutellite" are consistent with the replacement of half of the Mn4+ and O2- in ramsdellite by Mn3+ and (OH)-, respectively. In addition, the high-temperature behaviors of ramsdellite and "groutellite" were investigated by temperature-resolved synchrotron powder X-ray diffraction from 298 to 720 K. Rietveld refinements revealed a gradual thermal expansion of the groutellite structure to ∼ 450 K. At higher temperatures, the unit-cell volume gradually decreased, primarily as a result of a decrease in c.

Original languageEnglish (US)
Pages (from-to)969-975
Number of pages7
JournalAmerican Mineralogist
Volume89
Issue number7
DOIs
StatePublished - Jan 1 2004

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Dehydration
dehydration
Neutrons
X-ray diffraction
neutron diffraction
neutrons
X ray diffraction
thermal expansion
cells
diffraction
crystal structure
electric batteries
Rietveld method
Jahn-Teller effect
synchrotrons
Rietveld refinement
Neutron powder diffraction
x rays
replacement
Bond length

All Science Journal Classification (ASJC) codes

  • Geophysics
  • Geochemistry and Petrology

Cite this

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title = "Neutron and synchroton X-ray diffraction study of the structures and dehydration behaviors of ramsdellite and {"}groutellite{"}",
abstract = "The crystal structure of ramsdellite, MnO2, was refined using time-of-flight powder neutron diffraction data and the Rietveld method in order to assess the effects of reduction in cathodic battery materials. For the first time, we present a refined structure for {"}groutellite,{"} a heretofore poorly characterized phase with ideal formula (Mn0.5 4+Mn0.5 3+ O1.5(OH)0.5. {"}Groutellite{"} is generated synthetically as an intermediate compound during the reduction of ramsdellite to groutite (MnOOH), and it also occurs as an intergrowth in certain natural specimens of ramsdellite. The Jahn-Teller distortions in {"}groutellite{"} are confined to the a-c plane, and they result in a 6.8{\%} unit-cell volume increase relative to ramsdellite. The Mn-O bond lengths refined for {"}groutellite{"} are consistent with the replacement of half of the Mn4+ and O2- in ramsdellite by Mn3+ and (OH)-, respectively. In addition, the high-temperature behaviors of ramsdellite and {"}groutellite{"} were investigated by temperature-resolved synchrotron powder X-ray diffraction from 298 to 720 K. Rietveld refinements revealed a gradual thermal expansion of the groutellite structure to ∼ 450 K. At higher temperatures, the unit-cell volume gradually decreased, primarily as a result of a decrease in c.",
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Neutron and synchroton X-ray diffraction study of the structures and dehydration behaviors of ramsdellite and "groutellite". / Post, Jeffrey E.; Heaney, Peter J.

In: American Mineralogist, Vol. 89, No. 7, 01.01.2004, p. 969-975.

Research output: Contribution to journalArticle

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AB - The crystal structure of ramsdellite, MnO2, was refined using time-of-flight powder neutron diffraction data and the Rietveld method in order to assess the effects of reduction in cathodic battery materials. For the first time, we present a refined structure for "groutellite," a heretofore poorly characterized phase with ideal formula (Mn0.5 4+Mn0.5 3+ O1.5(OH)0.5. "Groutellite" is generated synthetically as an intermediate compound during the reduction of ramsdellite to groutite (MnOOH), and it also occurs as an intergrowth in certain natural specimens of ramsdellite. The Jahn-Teller distortions in "groutellite" are confined to the a-c plane, and they result in a 6.8% unit-cell volume increase relative to ramsdellite. The Mn-O bond lengths refined for "groutellite" are consistent with the replacement of half of the Mn4+ and O2- in ramsdellite by Mn3+ and (OH)-, respectively. In addition, the high-temperature behaviors of ramsdellite and "groutellite" were investigated by temperature-resolved synchrotron powder X-ray diffraction from 298 to 720 K. Rietveld refinements revealed a gradual thermal expansion of the groutellite structure to ∼ 450 K. At higher temperatures, the unit-cell volume gradually decreased, primarily as a result of a decrease in c.

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