Hydrogen bond effects on compressional behavior of isotypic minerals: high-pressure polymorphism of cristobalite-like Be(OH)₂

Autor(en)

Hannah Shelton, Madison C. Barkley, Robert T. Downs, Ronald Miletich-Pawliczek, Przemyslaw Dera

Abstrakt

Three isotypic crystals, SiO2 (a-cristobalite), e-Zn(OH)2 (wülfingite), and Be(OH)2 (ß-behoite), with topologically identical frameworks of corner-connected tetrahedra, undergo displacive compression-driven phase transitions at similar pressures (1.5-2.0 GPa), but each transition is characterized by a different mechanism resulting in different structural modifications. In this study, we report the crystal structure of the high-pressure ?-phase of beryllium hydroxide and compare it with the high-pressure structures of the other two minerals. In Be(OH)2, the transition from the ambient ß-behoite phase with the orthorhombic space group P212121 and ambient unit cell parameters a = 4.5403(4) Å, b = 4.6253(5) Å, c = 7.0599(7) Å, to the high-pressure orthorhombic ?-polymorph with space group Fdd2 and unit cell parameters (at 5.3(1) GPa) a = 5.738(2) Å, b = 6.260(3) Å, c = 7.200(4) Å takes place between 1.7 and 3.6 GPa. This transition is essentially second order, is accompanied by a negligible volume discontinuity, and exhibits both displacive and reversible character. The mechanism of the phase transition results in a change to the hydrogen bond connectivities and rotation of the BeO4 tetrahedra.

Organisation(en)

Institut für Mineralogie und Kristallographie

Externe Organisation(en)

University of Hawaii at Manoa, University of Arizona, Arizona Historical Society

Journal

Physics and Chemistry of Minerals

Band

43

Seiten

571-586

Anzahl der Seiten

16

ISSN

0342-1791

DOI

https://doi.org/10.1007/s00269-016-0818-5

Publikationsdatum

05-2016

Peer-reviewed

Ja

ÖFOS 2012

105116 Mineralogie, 105113 Kristallographie

Schlagwörter

ASJC Scopus Sachgebiete

Geochemistry and Petrology, Allgemeine Materialwissenschaften

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/8944af8c-d529-471e-b668-e1145d32d8ab