TY  - JOUR
AU  - Wiethoff, Felix
AU  - Grevel, Klaus-Dieter
AU  - Marler, Bernd
AU  - Petrikis, Julia
AU  - Majzlan, Juraj
AU  - Kirste, Jens
AU  - Lathe, Christian
TI  - P-V-T behavior of FeO(OH) and MnO(OH)
JO  - Physics and chemistry of minerals
VL  - 44
IS  - 8
SN  - 1432-2021
CY  - Berlin
PB  - Springer
M1  - PUBDB-2017-13930
SP  - 567 - 576
PY  - 2017
N1  - © Springer-Verlag Berlin Heidelberg ; Post referee fulltext in progress; Embargo 12 months from publication 
AB  - The P-V-T behavior of FeO(OH) and MnO(OH) has been determined under high pressure and high temperature up to 7.5 GPa and 500 °C using a MAX 80 cubic anvil high-pressure apparatus. The samples, synthetic goethite, α-FeO(OH), respectively, a natural groutite/manganite, α-MnO(OH)/γ-MnO(OH), specimen were mixed with Vaseline to ensure hydrostatic pressure-transmitting conditions, and NaCl served as an internal standard for pressure calibration. Energy-dispersive diffraction patterns were collected at a fixed 2θ angle (θ ≈ 4.52°). At pressures >7.1 GPa and temperatures >310 °C, respectively, P > 6.3 GPa and T > 350 °C, the transformation goethite ↔ ε-FeO(OH) was observed. Between 400 and 450 °C, the sample dehydrated to magnetite due to the reducing conditions caused by the graphite-tube furnace. By fitting a Birch–Murnaghan equation of state to the data, the bulk modulus of goethite was determined as (112.26 ± 2.26) GPa, (K′ = 4), V<sub>T,0</sub> = (138.79 ± 0.10) Å<sup>3</sup>·exp [∫(0.497 ± 0.103) × 10<sup>−4</sup> dT], (∂KT/∂T)P = (–0.033 ± 0.020) GPa K<sup>−1</sup>. For ε-FeO(OH), the values K = (142.8 ± 15.1) GPa, V0 = (66.18 ± 0.16) Å<sup>3</sup>, (K′ = 4), were obtained. Groutite and manganite are more compressible than their Fe analogues. K(groutite) = (84.0 ± 2.9) GPa, V<sub>0</sub> = (139.92 ± 0.13) Å<sup>3</sup>, (K′ = 4). K(manganite) = (82.2 ± 3.0) GPa, V<sub>0</sub> = (135.37 ± 0.15) Å<sup>3</sup>, (K′ = 4). Groutite disappeared at P ≈ 5.5 GPa and T = 300 °C, only manganite remained. At T > 400 °C, the sample dehydrated first to Mn<sub>3</sub>O<sub>4</sub> [II] and then to manganosite (MnO) again pointing to reducing conditions.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000422366600005
DO  - DOI:10.1007/s00269-017-0884-3
UR  - https://bib-pubdb1.desy.de/record/398355
ER  -