A new high-pressure phase transition in natural gedrite

Tommy Yong; Craig R. Bina; Gregory J. Finkelstein; Dongzhou Zhang; Przemyslaw Dera

doi:10.3390/cryst9100521

A new high-pressure phase transition in natural gedrite

Tommy Yong, Craig R. Bina, Gregory J. Finkelstein, Dongzhou Zhang, Przemyslaw Dera^*

^*Corresponding author for this work

Earth and Planetary Sciences

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

Abstract

High-pressure diamond-anvil cell synchrotron X-ray diffraction experiments were conducted on single-crystal samples of natural orthoamphibole; gedrite; with composition; (K_0.002Na_0.394)(Mg₂)(Mg_1.637Fe_2.245Mn_0.004Ca_0.022Cr_0.003Na_0.037Al_1.052)(Si_6.517Al_1.483)O₂₂(OH)₂. The samples were compressed at 298 K up to a maximum pressure of 27(1) GPa. In this pressure regime, we observed a displacive phase transition between 15.1(7) and 21(1) GPa from the orthorhombic Pnma phase to a new structure with space group P2₁/m; which is different from the familiar P2₁/m structure of cummingtonite and retains the (+, +, −, −) I-beam stacking sequence of the orthorhombic structure. The unit cell parameters for the new phase at 21(1) GPa are a = 17.514(3), b = 17.077(1), c = 4.9907(2) Å and β = 92.882(6)^◦. The high-pressure P2₁/m phase is the first amphibole structure to show the existence of four crystallographically distinct silicate double chains. The orthorhombic to monoclinic phase transition is characterized by an increase in the degree of kinking of the double silicate chains and is analogous to displacive phase changes recently reported in orthopyroxenes, highlighting the parallel structural relations and phase transformation behavior of orthorhombic single-and double-chain silicates.

Original language	English (US)
Article number	521
Journal	Crystals
Volume	9
Issue number	10
DOIs	https://doi.org/10.3390/cryst9100521
State	Published - Oct 2019

Keywords

Amphibole
Diamond anvil cell
High-pressure
Phase transition
Single-crystal X-ray diffraction
Synchrotron source

ASJC Scopus subject areas

Chemical Engineering(all)
Materials Science(all)
Condensed Matter Physics
Inorganic Chemistry

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@article{49ef3bba9a8c4a44a31fbc5c4aeddc6e,

title = "A new high-pressure phase transition in natural gedrite",

abstract = "High-pressure diamond-anvil cell synchrotron X-ray diffraction experiments were conducted on single-crystal samples of natural orthoamphibole; gedrite; with composition; (K0.002Na0.394)(Mg2)(Mg1.637Fe2.245Mn0.004Ca0.022Cr0.003Na0.037Al1.052)(Si6.517Al1.483)O22(OH)2. The samples were compressed at 298 K up to a maximum pressure of 27(1) GPa. In this pressure regime, we observed a displacive phase transition between 15.1(7) and 21(1) GPa from the orthorhombic Pnma phase to a new structure with space group P21/m; which is different from the familiar P21/m structure of cummingtonite and retains the (+, +, −, −) I-beam stacking sequence of the orthorhombic structure. The unit cell parameters for the new phase at 21(1) GPa are a = 17.514(3), b = 17.077(1), c = 4.9907(2) {\AA} and β = 92.882(6)◦. The high-pressure P21/m phase is the first amphibole structure to show the existence of four crystallographically distinct silicate double chains. The orthorhombic to monoclinic phase transition is characterized by an increase in the degree of kinking of the double silicate chains and is analogous to displacive phase changes recently reported in orthopyroxenes, highlighting the parallel structural relations and phase transformation behavior of orthorhombic single-and double-chain silicates.",

keywords = "Amphibole, Diamond anvil cell, High-pressure, Phase transition, Single-crystal X-ray diffraction, Synchrotron source",

author = "Tommy Yong and Bina, {Craig R.} and Finkelstein, {Gregory J.} and Dongzhou Zhang and Przemyslaw Dera",

year = "2019",

month = oct,

doi = "10.3390/cryst9100521",

language = "English (US)",

volume = "9",

journal = "Crystals",

issn = "2073-4352",

publisher = "Multidisciplinary Digital Publishing Institute (MDPI)",

number = "10",

}

TY - JOUR

T1 - A new high-pressure phase transition in natural gedrite

AU - Yong, Tommy

AU - Bina, Craig R.

AU - Finkelstein, Gregory J.

AU - Zhang, Dongzhou

AU - Dera, Przemyslaw

PY - 2019/10

Y1 - 2019/10

N2 - High-pressure diamond-anvil cell synchrotron X-ray diffraction experiments were conducted on single-crystal samples of natural orthoamphibole; gedrite; with composition; (K0.002Na0.394)(Mg2)(Mg1.637Fe2.245Mn0.004Ca0.022Cr0.003Na0.037Al1.052)(Si6.517Al1.483)O22(OH)2. The samples were compressed at 298 K up to a maximum pressure of 27(1) GPa. In this pressure regime, we observed a displacive phase transition between 15.1(7) and 21(1) GPa from the orthorhombic Pnma phase to a new structure with space group P21/m; which is different from the familiar P21/m structure of cummingtonite and retains the (+, +, −, −) I-beam stacking sequence of the orthorhombic structure. The unit cell parameters for the new phase at 21(1) GPa are a = 17.514(3), b = 17.077(1), c = 4.9907(2) Å and β = 92.882(6)◦. The high-pressure P21/m phase is the first amphibole structure to show the existence of four crystallographically distinct silicate double chains. The orthorhombic to monoclinic phase transition is characterized by an increase in the degree of kinking of the double silicate chains and is analogous to displacive phase changes recently reported in orthopyroxenes, highlighting the parallel structural relations and phase transformation behavior of orthorhombic single-and double-chain silicates.

AB - High-pressure diamond-anvil cell synchrotron X-ray diffraction experiments were conducted on single-crystal samples of natural orthoamphibole; gedrite; with composition; (K0.002Na0.394)(Mg2)(Mg1.637Fe2.245Mn0.004Ca0.022Cr0.003Na0.037Al1.052)(Si6.517Al1.483)O22(OH)2. The samples were compressed at 298 K up to a maximum pressure of 27(1) GPa. In this pressure regime, we observed a displacive phase transition between 15.1(7) and 21(1) GPa from the orthorhombic Pnma phase to a new structure with space group P21/m; which is different from the familiar P21/m structure of cummingtonite and retains the (+, +, −, −) I-beam stacking sequence of the orthorhombic structure. The unit cell parameters for the new phase at 21(1) GPa are a = 17.514(3), b = 17.077(1), c = 4.9907(2) Å and β = 92.882(6)◦. The high-pressure P21/m phase is the first amphibole structure to show the existence of four crystallographically distinct silicate double chains. The orthorhombic to monoclinic phase transition is characterized by an increase in the degree of kinking of the double silicate chains and is analogous to displacive phase changes recently reported in orthopyroxenes, highlighting the parallel structural relations and phase transformation behavior of orthorhombic single-and double-chain silicates.

KW - Amphibole

KW - Diamond anvil cell

KW - High-pressure

KW - Phase transition

KW - Single-crystal X-ray diffraction

KW - Synchrotron source

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U2 - 10.3390/cryst9100521

DO - 10.3390/cryst9100521

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VL - 9

JO - Crystals

JF - Crystals

SN - 2073-4352

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