Thorite: An oddity in phase stability among the zircon-structured orthosilicates at high pressures

Andrew C. Strzelecki; Jason L. Baker; Stella Chariton; Xiaodong Zhao; Vitali Prakapenka; David Bollinger; Sohan Ahmed; Jeffrey Fortner; Stephanie Szenknect; Adel Mesbah; John S. McCloy; Choong Shik Yoo; Rodney C. Ewing; Nicolas Dacheux; Hongwu Xu; Xiaofeng Guo

doi:10.2138/am-2024-9443

Thorite: An oddity in phase stability among the zircon-structured orthosilicates at high pressures

Andrew C. Strzelecki
, Jason L. Baker
, Stella Chariton
, Xiaodong Zhao
, Vitali Prakapenka
, David Bollinger
, Sohan Ahmed
, Jeffrey Fortner
, Stephanie Szenknect
, Adel Mesbah
, John S. McCloy
, Choong Shik Yoo
, Rodney C. Ewing
, Nicolas Dacheux
, Hongwu Xu
, Xiaofeng Guo

Used Fuel & Nuclear Material Disposition

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

Abstract

Synthetic thorite and huttonite, two polymorphs of ThSiO₄, were investigated by a combination of in situ high-pressure synchrotron X-ray powder diffraction and in situ high-pressure Raman spectroscopy. The average onset pressure of the thorite-to-huttonite transition was determined to be 6.6 ± 0.2 GPa, using both techniques. The bulk moduli of thorite and huttonite were determined to be 139(9) and 246(11) GPa, respectively, by fitting their unit-cell volume data to a second-order Birch-Murnaghan equation of state (EOS). Based on its bulk modulus, thorite is the most compressible zircon-structured orthosilicate, as it has the largest unit-cell volume among tetravalent metal orthosilicates. The pressure derivatives of the vibrational modes of thorite were found to be consistent with those previously reported for other orthosilicates (e.g., zircon, hafnon, stetindite, and coffinite), while having the smallest Grüneisen parameter. A new P-T phase diagram for ThSiO₄ is proposed, where the boundary of the thorite →huttonite transition is: P(T) = (7.8 ± 0.9 GPa) – (0.006 ± 0.002 GPa/K)T. Based on the new P-T phase diagram, we further estimated the enthalpy of formation of huttonite, ΔH _f,ox, to be 0.6± 6.0 kJ/mol, suggesting its metastability and rare locality in nature.

Original language	English
Pages (from-to)	1428-1436
Number of pages	9
Journal	American Mineralogist
Volume	110
Issue number	9
DOIs	https://doi.org/10.2138/am-2024-9443
State	Published - Sep 1 2025

Funding

This work was supported by the institutional funds from the Department of Chemistry at Washington State University in the early stage and later supported by the National Science Foundation (NSF), Division of Earth Sciences, under award no. 2149848, and Division of Materials Research, under award no. 2144792. We also acknowledge the help from the Alexandra Navrotsky Institute for Experimental Thermodynamics, and the WSU-PNNL Nuclear Science and Technology Institute. Research presented in this article was supported by the Laboratory Directed Research and Development (LDRD) program of Los Alamos National Laboratory (LANL) under project number 20180007DR. LANL, an affirmative action/equal opportunity employer, is managed by Triad National Security, LLC, for the National Nuclear Security Administration of the U.S. Department of Energy under contract 89233218CNA000001. A portion of this work was performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS), Argonne National Laboratory. GeoSoilEnviroCARS is supported by the NSF–Earth Sciences (EAR-1634415). This research used resources of the Advanced Photon Source, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357. This work was supported by the institutional funds from the Department ofChemistry at Washington State University in the early stage and later supportedbythe NationalScienceFoundation (NSF),DivisionofEarthSciences, underawardno. 2149848, and Division of Materials Research, under award no. 2144792. Wealso acknowledgethe help from the Alexandra Navrotsky Institute for ExperimentalThermodynamics, and the WSU-PNNL Nuclear Science and Technology Institute.Research presented in this article was supported by the Laboratory DirectedResearch and Development (LDRD) program of Los Alamos National Laboratory(LANL) under project number 20180007DR. LANL, an affirmative action/equalopportunity employer,ismanagedbyTriadNationalSecurity,LLC,forthe NationalNuclear Security Administration of the U.S. Department of Energy under contract89233218CNA000001. A portion of this work was performed at GeoSoilEnviroCARS (The University of Chicago, Sector 13), Advanced Photon Source (APS),ArgonneNational Laboratory. GeoSoilEnviroCARSissupportedbythe NSF–EarthSciences (EAR-1634415). This research used resources of the Advanced PhotonSource, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOEOffice ofSciencebyArgonne National Laboratoryunder ContractNo. DE-AC02-06CH11357

Keywords

Thorite
X-ray diffraction
equation of state
high pressure
huttonite
metastability
phase diagram

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10.2138/am-2024-9443

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Strzelecki, A. C., Baker, J. L., Chariton, S., Zhao, X., Prakapenka, V., Bollinger, D., Ahmed, S., Fortner, J., Szenknect, S., Mesbah, A., McCloy, J. S., Yoo, C. S., Ewing, R. C., Dacheux, N., Xu, H., & Guo, X. (2025). Thorite: An oddity in phase stability among the zircon-structured orthosilicates at high pressures. American Mineralogist, 110(9), 1428-1436. https://doi.org/10.2138/am-2024-9443

@article{d08ff15ee1a047fe989265576bdaa510,

title = "Thorite: An oddity in phase stability among the zircon-structured orthosilicates at high pressures",

abstract = "Synthetic thorite and huttonite, two polymorphs of ThSiO4, were investigated by a combination of in situ high-pressure synchrotron X-ray powder diffraction and in situ high-pressure Raman spectroscopy. The average onset pressure of the thorite-to-huttonite transition was determined to be 6.6 ± 0.2 GPa, using both techniques. The bulk moduli of thorite and huttonite were determined to be 139(9) and 246(11) GPa, respectively, by fitting their unit-cell volume data to a second-order Birch-Murnaghan equation of state (EOS). Based on its bulk modulus, thorite is the most compressible zircon-structured orthosilicate, as it has the largest unit-cell volume among tetravalent metal orthosilicates. The pressure derivatives of the vibrational modes of thorite were found to be consistent with those previously reported for other orthosilicates (e.g., zircon, hafnon, stetindite, and coffinite), while having the smallest Gr{\"u}neisen parameter. A new P-T phase diagram for ThSiO4 is proposed, where the boundary of the thorite →huttonite transition is: P(T) = (7.8 ± 0.9 GPa) – (0.006 ± 0.002 GPa/K)T. Based on the new P-T phase diagram, we further estimated the enthalpy of formation of huttonite, ΔH f,ox, to be 0.6± 6.0 kJ/mol, suggesting its metastability and rare locality in nature.",

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note = "Publisher Copyright: {\textcopyright} 2025 Mineralogical Society of America.",

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doi = "10.2138/am-2024-9443",

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Strzelecki, AC, Baker, JL, Chariton, S, Zhao, X, Prakapenka, V, Bollinger, D, Ahmed, S, Fortner, J, Szenknect, S, Mesbah, A, McCloy, JS, Yoo, CS, Ewing, RC, Dacheux, N, Xu, H & Guo, X 2025, 'Thorite: An oddity in phase stability among the zircon-structured orthosilicates at high pressures', American Mineralogist, vol. 110, no. 9, pp. 1428-1436. https://doi.org/10.2138/am-2024-9443

TY - JOUR

T1 - Thorite

T2 - An oddity in phase stability among the zircon-structured orthosilicates at high pressures

AU - Strzelecki, Andrew C.

AU - Baker, Jason L.

AU - Chariton, Stella

AU - Zhao, Xiaodong

AU - Prakapenka, Vitali

AU - Bollinger, David

AU - Ahmed, Sohan

AU - Fortner, Jeffrey

AU - Szenknect, Stephanie

AU - Mesbah, Adel

AU - McCloy, John S.

AU - Yoo, Choong Shik

AU - Ewing, Rodney C.

AU - Dacheux, Nicolas

AU - Xu, Hongwu

AU - Guo, Xiaofeng

PY - 2025/9/1

Y1 - 2025/9/1

N2 - Synthetic thorite and huttonite, two polymorphs of ThSiO4, were investigated by a combination of in situ high-pressure synchrotron X-ray powder diffraction and in situ high-pressure Raman spectroscopy. The average onset pressure of the thorite-to-huttonite transition was determined to be 6.6 ± 0.2 GPa, using both techniques. The bulk moduli of thorite and huttonite were determined to be 139(9) and 246(11) GPa, respectively, by fitting their unit-cell volume data to a second-order Birch-Murnaghan equation of state (EOS). Based on its bulk modulus, thorite is the most compressible zircon-structured orthosilicate, as it has the largest unit-cell volume among tetravalent metal orthosilicates. The pressure derivatives of the vibrational modes of thorite were found to be consistent with those previously reported for other orthosilicates (e.g., zircon, hafnon, stetindite, and coffinite), while having the smallest Grüneisen parameter. A new P-T phase diagram for ThSiO4 is proposed, where the boundary of the thorite →huttonite transition is: P(T) = (7.8 ± 0.9 GPa) – (0.006 ± 0.002 GPa/K)T. Based on the new P-T phase diagram, we further estimated the enthalpy of formation of huttonite, ΔH f,ox, to be 0.6± 6.0 kJ/mol, suggesting its metastability and rare locality in nature.

AB - Synthetic thorite and huttonite, two polymorphs of ThSiO4, were investigated by a combination of in situ high-pressure synchrotron X-ray powder diffraction and in situ high-pressure Raman spectroscopy. The average onset pressure of the thorite-to-huttonite transition was determined to be 6.6 ± 0.2 GPa, using both techniques. The bulk moduli of thorite and huttonite were determined to be 139(9) and 246(11) GPa, respectively, by fitting their unit-cell volume data to a second-order Birch-Murnaghan equation of state (EOS). Based on its bulk modulus, thorite is the most compressible zircon-structured orthosilicate, as it has the largest unit-cell volume among tetravalent metal orthosilicates. The pressure derivatives of the vibrational modes of thorite were found to be consistent with those previously reported for other orthosilicates (e.g., zircon, hafnon, stetindite, and coffinite), while having the smallest Grüneisen parameter. A new P-T phase diagram for ThSiO4 is proposed, where the boundary of the thorite →huttonite transition is: P(T) = (7.8 ± 0.9 GPa) – (0.006 ± 0.002 GPa/K)T. Based on the new P-T phase diagram, we further estimated the enthalpy of formation of huttonite, ΔH f,ox, to be 0.6± 6.0 kJ/mol, suggesting its metastability and rare locality in nature.

KW - Thorite

KW - X-ray diffraction

KW - equation of state

KW - high pressure

KW - huttonite

KW - metastability

KW - phase diagram

UR - https://www.scopus.com/pages/publications/105017662318

U2 - 10.2138/am-2024-9443

DO - 10.2138/am-2024-9443

M3 - Article

AN - SCOPUS:105017662318

SN - 0003-004X

VL - 110

SP - 1428

EP - 1436

JO - American Mineralogist

JF - American Mineralogist

IS - 9

ER -

Thorite: An oddity in phase stability among the zircon-structured orthosilicates at high pressures

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