Single-crystal elastic properties of alunite, KAl3 (SO4)2(OH)6

Juraj Majzlan; S. Speziale; T. S. Duffy; P. C. Burns

doi:10.1007/s00269-006-0104-z

Single-crystal elastic properties of alunite, KAl₃ (SO₄)₂(OH)₆

Juraj Majzlan, S. Speziale, T. S. Duffy, P. C. Burns

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

21 Scopus citations

Abstract

The single-crystal elastic constants of natural alunite (ideally KAl₃(SO₄)₂(OH)₆) were determined by Brillouin spectroscopy. Chemical analysis by electron microprobe gave a formula KAl₃(SO₄)₂ (OH)₆. Single crystal X-ray diffraction refinement with R₁ = 0.0299 for the unique observed reflections (Fο > 4σ_F) and wR ₂ = 0.0698 for all data gave a = 6.9741(3) Å, c = 17.190(2) Å, fractional positions and thermal factors for all atoms. The elastic constants (in GPa), obtained by fitting the spectroscopic data, are C₁₁ = 181.9 ± 0.3, C₃₃ = 66.8 ± 0.8, C₄₄ = 42.8 ±0.2, C₁₂ = 48.2 ± 0.5, C₁₃ = 27.1 ± 1.0, C₁₄ = 5.4 ± 0.5, and C₆₆ = (C₁₁-C₁₂) = 66.9 ± 0.3 GPa. The VRH averages of bulk and shear modulus are 63 and 49 GPa, respectively. The aggregate Poisson ratio is 0.19. The high value of the ratio C₁₁/C₃₃ = 2.7 and of the ratio C₆₆/C₄₄ = 1.6 are characteristic of an anisotropic structure with very weak interlayer interactions along the c-axis. The basal plane (001) is characterized by 0.1% longitudinal acoustic anisotropy and 0.9-1.1% shear acoustic anisotropy, which gives alunite a characteristic pseudo-hexagonal elastic behavior, and is related to the pseudo-hexagonal arrangement of the Al(O,OH)₆ octahedra in the basal layer. The elastic Debye temperature of alunite is 654 K. The large discrepancy between the elastic and heat capacity Debye temperature is also a consequence of the layered structure.

Original language	English (US)
Pages (from-to)	567-573
Number of pages	7
Journal	Physics and Chemistry of Minerals
Volume	33
Issue number	8-9
DOIs	https://doi.org/10.1007/s00269-006-0104-z
State	Published - Nov 2006

All Science Journal Classification (ASJC) codes

General Materials Science
Geochemistry and Petrology

Keywords

Alunite
Crystal structure
Elastic constants

Access to Document

10.1007/s00269-006-0104-z

Cite this

@article{e65819fe61c540f9b813d4f19f07039f,

title = "Single-crystal elastic properties of alunite, KAl3 (SO4)2(OH)6",

abstract = "The single-crystal elastic constants of natural alunite (ideally KAl3(SO4)2(OH)6) were determined by Brillouin spectroscopy. Chemical analysis by electron microprobe gave a formula KAl3(SO4)2 (OH)6. Single crystal X-ray diffraction refinement with R1 = 0.0299 for the unique observed reflections (Fο > 4σF) and wR 2 = 0.0698 for all data gave a = 6.9741(3) {\AA}, c = 17.190(2) {\AA}, fractional positions and thermal factors for all atoms. The elastic constants (in GPa), obtained by fitting the spectroscopic data, are C11 = 181.9 ± 0.3, C33 = 66.8 ± 0.8, C44 = 42.8 ±0.2, C12 = 48.2 ± 0.5, C13 = 27.1 ± 1.0, C14 = 5.4 ± 0.5, and C66 = (C11-C12) = 66.9 ± 0.3 GPa. The VRH averages of bulk and shear modulus are 63 and 49 GPa, respectively. The aggregate Poisson ratio is 0.19. The high value of the ratio C11/C33 = 2.7 and of the ratio C66/C44 = 1.6 are characteristic of an anisotropic structure with very weak interlayer interactions along the c-axis. The basal plane (001) is characterized by 0.1% longitudinal acoustic anisotropy and 0.9-1.1% shear acoustic anisotropy, which gives alunite a characteristic pseudo-hexagonal elastic behavior, and is related to the pseudo-hexagonal arrangement of the Al(O,OH)6 octahedra in the basal layer. The elastic Debye temperature of alunite is 654 K. The large discrepancy between the elastic and heat capacity Debye temperature is also a consequence of the layered structure.",

keywords = "Alunite, Crystal structure, Elastic constants",

author = "Juraj Majzlan and S. Speziale and Duffy, {T. S.} and Burns, {P. C.}",

year = "2006",

month = nov,

doi = "10.1007/s00269-006-0104-z",

language = "English (US)",

volume = "33",

pages = "567--573",

journal = "Physics and Chemistry of Minerals",

issn = "0342-1791",

publisher = "Springer Verlag",

number = "8-9",

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TY - JOUR

T1 - Single-crystal elastic properties of alunite, KAl3 (SO4)2(OH)6

AU - Majzlan, Juraj

AU - Speziale, S.

AU - Duffy, T. S.

AU - Burns, P. C.

PY - 2006/11

Y1 - 2006/11

N2 - The single-crystal elastic constants of natural alunite (ideally KAl3(SO4)2(OH)6) were determined by Brillouin spectroscopy. Chemical analysis by electron microprobe gave a formula KAl3(SO4)2 (OH)6. Single crystal X-ray diffraction refinement with R1 = 0.0299 for the unique observed reflections (Fο > 4σF) and wR 2 = 0.0698 for all data gave a = 6.9741(3) Å, c = 17.190(2) Å, fractional positions and thermal factors for all atoms. The elastic constants (in GPa), obtained by fitting the spectroscopic data, are C11 = 181.9 ± 0.3, C33 = 66.8 ± 0.8, C44 = 42.8 ±0.2, C12 = 48.2 ± 0.5, C13 = 27.1 ± 1.0, C14 = 5.4 ± 0.5, and C66 = (C11-C12) = 66.9 ± 0.3 GPa. The VRH averages of bulk and shear modulus are 63 and 49 GPa, respectively. The aggregate Poisson ratio is 0.19. The high value of the ratio C11/C33 = 2.7 and of the ratio C66/C44 = 1.6 are characteristic of an anisotropic structure with very weak interlayer interactions along the c-axis. The basal plane (001) is characterized by 0.1% longitudinal acoustic anisotropy and 0.9-1.1% shear acoustic anisotropy, which gives alunite a characteristic pseudo-hexagonal elastic behavior, and is related to the pseudo-hexagonal arrangement of the Al(O,OH)6 octahedra in the basal layer. The elastic Debye temperature of alunite is 654 K. The large discrepancy between the elastic and heat capacity Debye temperature is also a consequence of the layered structure.

AB - The single-crystal elastic constants of natural alunite (ideally KAl3(SO4)2(OH)6) were determined by Brillouin spectroscopy. Chemical analysis by electron microprobe gave a formula KAl3(SO4)2 (OH)6. Single crystal X-ray diffraction refinement with R1 = 0.0299 for the unique observed reflections (Fο > 4σF) and wR 2 = 0.0698 for all data gave a = 6.9741(3) Å, c = 17.190(2) Å, fractional positions and thermal factors for all atoms. The elastic constants (in GPa), obtained by fitting the spectroscopic data, are C11 = 181.9 ± 0.3, C33 = 66.8 ± 0.8, C44 = 42.8 ±0.2, C12 = 48.2 ± 0.5, C13 = 27.1 ± 1.0, C14 = 5.4 ± 0.5, and C66 = (C11-C12) = 66.9 ± 0.3 GPa. The VRH averages of bulk and shear modulus are 63 and 49 GPa, respectively. The aggregate Poisson ratio is 0.19. The high value of the ratio C11/C33 = 2.7 and of the ratio C66/C44 = 1.6 are characteristic of an anisotropic structure with very weak interlayer interactions along the c-axis. The basal plane (001) is characterized by 0.1% longitudinal acoustic anisotropy and 0.9-1.1% shear acoustic anisotropy, which gives alunite a characteristic pseudo-hexagonal elastic behavior, and is related to the pseudo-hexagonal arrangement of the Al(O,OH)6 octahedra in the basal layer. The elastic Debye temperature of alunite is 654 K. The large discrepancy between the elastic and heat capacity Debye temperature is also a consequence of the layered structure.

KW - Alunite

KW - Crystal structure

KW - Elastic constants

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U2 - 10.1007/s00269-006-0104-z

DO - 10.1007/s00269-006-0104-z

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JO - Physics and Chemistry of Minerals

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