Thermal expansion and decomposition of jarosite: A high-temperature neutron diffraction study

Hongwu Xu; Yusheng Zhao; Sven C. Vogel; Donald D. Hickmott; Luke L. Daemen; Monika A. Hartl

doi:10.1007/s00269-009-0311-5

Thermal expansion and decomposition of jarosite: A high-temperature neutron diffraction study

Hongwu Xu, Yusheng Zhao, Sven C. Vogel, Donald D. Hickmott, Luke L. Daemen, Monika A. Hartl

Research output: Contribution to journal › Article › peer-review

19 Scopus citations

Abstract

The structure of deuterated jarosite, KFe₃(SO₄)₂(OD)₆, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals that with increasing temperature, its c dimension expands at a rate ~ 10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH)₆] octahedra and [SO₄] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, α = α₀ + α₁T, where α₀ = 1.01 × 10^-4 K^-1 and a1 = -1.15 × 10^-7 K^-2. On heating, the hydrogen bonds, O1⋯-O3, through which the (001) octahedral-tetrahedral sheets are held together, become weakened, as reflected by an increase in the D⋯O1 distance and a concomitant decrease in the O3-D distance with increasing temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together.

Original language	English
Pages (from-to)	73-82
Number of pages	10
Journal	Physics and Chemistry of Minerals
Volume	37
Issue number	2
DOIs	https://doi.org/10.1007/s00269-009-0311-5
State	Published - 2010
Externally published	Yes

Funding

We thank P.J. Heaney and an anonymous reviewer for helpful comments, and M.S. Rearick for carrying out compositional analysis of the jarosite sample. This work has benefited from the use of the Lujan Neutron Scattering Center at LANSCE, which is funded by the Department of Energy’s Office of Basic Energy Sciences. Los Alamos National Laboratory is operated by Los Alamos National Security, LLC, under DOE Contract DE-AC52-06NA25396.

Funders	Funder number
U.S. Department of Energy	DE-AC52-06NA25396
Basic Energy Sciences

Keywords

Crystal chemistry
Decomposition
Hydrogen bonds
Jarosite
Neutron diffraction
Thermal expansion

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10.1007/s00269-009-0311-5

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title = "Thermal expansion and decomposition of jarosite: A high-temperature neutron diffraction study",

abstract = "The structure of deuterated jarosite, KFe3(SO4)2(OD)6, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals that with increasing temperature, its c dimension expands at a rate ~ 10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH)6] octahedra and [SO4] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, α = α0 + α1T, where α0 = 1.01 × 10-4 K-1 and a1 = -1.15 × 10-7 K-2. On heating, the hydrogen bonds, O1⋯-O3, through which the (001) octahedral-tetrahedral sheets are held together, become weakened, as reflected by an increase in the D⋯O1 distance and a concomitant decrease in the O3-D distance with increasing temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together.",

keywords = "Crystal chemistry, Decomposition, Hydrogen bonds, Jarosite, Neutron diffraction, Thermal expansion",

author = "Hongwu Xu and Yusheng Zhao and Vogel, {Sven C.} and Hickmott, {Donald D.} and Daemen, {Luke L.} and Hartl, {Monika A.}",

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T1 - Thermal expansion and decomposition of jarosite

T2 - A high-temperature neutron diffraction study

AU - Xu, Hongwu

AU - Zhao, Yusheng

AU - Vogel, Sven C.

AU - Hickmott, Donald D.

AU - Daemen, Luke L.

AU - Hartl, Monika A.

PY - 2010

Y1 - 2010

N2 - The structure of deuterated jarosite, KFe3(SO4)2(OD)6, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals that with increasing temperature, its c dimension expands at a rate ~ 10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH)6] octahedra and [SO4] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, α = α0 + α1T, where α0 = 1.01 × 10-4 K-1 and a1 = -1.15 × 10-7 K-2. On heating, the hydrogen bonds, O1⋯-O3, through which the (001) octahedral-tetrahedral sheets are held together, become weakened, as reflected by an increase in the D⋯O1 distance and a concomitant decrease in the O3-D distance with increasing temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together.

AB - The structure of deuterated jarosite, KFe3(SO4)2(OD)6, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals that with increasing temperature, its c dimension expands at a rate ~ 10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH)6] octahedra and [SO4] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, α = α0 + α1T, where α0 = 1.01 × 10-4 K-1 and a1 = -1.15 × 10-7 K-2. On heating, the hydrogen bonds, O1⋯-O3, through which the (001) octahedral-tetrahedral sheets are held together, become weakened, as reflected by an increase in the D⋯O1 distance and a concomitant decrease in the O3-D distance with increasing temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together.

KW - Crystal chemistry

KW - Decomposition

KW - Hydrogen bonds

KW - Jarosite

KW - Neutron diffraction

KW - Thermal expansion

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Thermal expansion and decomposition of jarosite: A high-temperature neutron diffraction study

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