TY - JOUR
T1 - Synchrotron X-ray analysis of norbergite, Mg2.98 Fe0.01Ti0.02Si0.99O4 (OH0.31F1.69) structure at high pressure up to 8.2 GPa
AU - Kuribayashi, Takahiro
AU - Tanaka, Masahiko
AU - Kudoh, Yasuhiro
N1 - Funding Information:
We thank Dr. W. Crichton and an anonymous reviewer for their helpful and constructive reviews. We are grateful to Prof. Matsui for editorial handling and useful comments. This study was supported by grants of Photon Factory in KEK, Japan (PAC No. 2005G010 and 2006G262).
PY - 2008
Y1 - 2008
N2 - The natural norbergite, Mg2.98Fe0.01 Ti0.02Si0.99O4 (OH0.31 F1.69) is examined by synchrotron X-ray diffraction analysis at pressures up to 8.2 GPa. The measured linear compressibilities of the crystallographic axes are βa = 2.18(4) × 10-3, βb = 2.93(7) × 10-3, and βc = 2.77(7) × 10-3 (GPa-1), respectively and the calculated isothermal bulk modulus of the norbergite is KT = 113(2) GPa based on the Birch-Murnaghan equation of state assuming a pressure derivative of K′ = 4. The crystal structures of norbergite are refined at room temperature and pressures of 4.7, 6.3, and 8.2 GPa, yielding R values for the structure refinements of 4.6, 5.3, and 5.3%, respectively. The bulk moduli of the polyhedral sites are 293(15) GPa for the tetrahedron, 106(5) GPa for the M2 octahedron, 113(2) GPa for the M3 octahedron, and 113(3) GPa for the total void space. The bulk modulus exhibits a good linear correlation with the filling factor for polyhedral sites in structures of the humite minerals and forsterite, reflecting the Si4+ + 4O2- ⇔ □ + 4(OH, F)- substitution in the humite minerals. Moreover, two simply linear trends were observed in the relationship between bulk modulus and packing index for natural minerals and dense hydrous magnesium silicate minerals. This relationship would reflect that the differences in compression mechanism were involved with hydrogen bonding in these minerals.
AB - The natural norbergite, Mg2.98Fe0.01 Ti0.02Si0.99O4 (OH0.31 F1.69) is examined by synchrotron X-ray diffraction analysis at pressures up to 8.2 GPa. The measured linear compressibilities of the crystallographic axes are βa = 2.18(4) × 10-3, βb = 2.93(7) × 10-3, and βc = 2.77(7) × 10-3 (GPa-1), respectively and the calculated isothermal bulk modulus of the norbergite is KT = 113(2) GPa based on the Birch-Murnaghan equation of state assuming a pressure derivative of K′ = 4. The crystal structures of norbergite are refined at room temperature and pressures of 4.7, 6.3, and 8.2 GPa, yielding R values for the structure refinements of 4.6, 5.3, and 5.3%, respectively. The bulk moduli of the polyhedral sites are 293(15) GPa for the tetrahedron, 106(5) GPa for the M2 octahedron, 113(2) GPa for the M3 octahedron, and 113(3) GPa for the total void space. The bulk modulus exhibits a good linear correlation with the filling factor for polyhedral sites in structures of the humite minerals and forsterite, reflecting the Si4+ + 4O2- ⇔ □ + 4(OH, F)- substitution in the humite minerals. Moreover, two simply linear trends were observed in the relationship between bulk modulus and packing index for natural minerals and dense hydrous magnesium silicate minerals. This relationship would reflect that the differences in compression mechanism were involved with hydrogen bonding in these minerals.
KW - Crystal structure
KW - High-pressure
KW - Norbergite
KW - Single-crystal X-ray diffraction
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U2 - 10.1007/s00269-008-0248-0
DO - 10.1007/s00269-008-0248-0
M3 - Article
AN - SCOPUS:56749153534
VL - 35
SP - 559
EP - 568
JO - Physics and Chemistry of Minerals
JF - Physics and Chemistry of Minerals
SN - 0342-1791
IS - 10
ER -