Estimation of polyhedral compressibilities and structural evolution of GdFeO3-type perovskites at high pressures

2006 ◽  
Vol 62 (3) ◽  
pp. 431-439 ◽  
Author(s):  
J. Zhao ◽  
N. L. Ross ◽  
R. J. Angel
Keyword(s):  
High Pressure ◽  
Single Crystal ◽  
High Pressures ◽  
Structural Evolution ◽  
Structural Data ◽  
New Approach ◽  
Cell Parameters ◽  
Pressure Unit ◽  
Crystal Structural Data ◽  
Crystal Structural

A new approach based on the bond-valence matching relation is developed to predict the detailed structural evolution of GdFeO3-type perovskites at high pressure from knowledge of the room-pressure structure and the high-pressure unit-cell parameters alone. The evolution of perovskite structures estimated in this way is in good agreement with the structure refinements available from high-pressure single-crystal diffraction measurements of a number of perovskites. The method is then extended to predict the structure of MgSiO3 perovskite at pressures for which no single-crystal structural data are available and the results are compared to ab initio quantum calculations of MgSiO3 perovskite up to 120 GPa.

Notizen: Einkristall-Strukturdaten einiger Fluoride und Cyanide A2IBIMIIIX6 der Elpasolithfamilie / Single Crystal Structural Data of Some Fluorides and Cyanides A2IBIMIIIX6 of the Elpasolite Family

1975 ◽  
Vol 30 (5-6) ◽  
pp. 462-464 ◽  
Author(s):  
R. Haegele ◽  
W. Verscharen ◽  
D. Babel
Keyword(s):  
Single Crystal ◽  
Structural Data ◽  
Space Group ◽  
X Ray ◽  
Lattice Constants ◽  
Structure Determinations ◽  
Crystal Structural Data ◽  
Crystal Structural

The parameters of complete X-ray structure determinations are given for the fluoridesRb2NaFeF6 and Rb2KFeF6 (cubic), Cs2NaCrF6 and Cs2NaFeF6 (hexagonal-rhom-bohedral) and Cs2LiGaF6 (hexagonal). Space group and lattice constants of the monoclinic cyanides Cs2BFe(CN)6 (B = Na, K, Rb) are reported as well.

Synthetic B-rich olenite: Correlations of single-crystal structural data

2012 ◽  
Vol 97 (10) ◽  
pp. 1591-1597 ◽  
Author(s):  
A. Ertl ◽  
G. Giester ◽  
T. Ludwig ◽  
H.-P. Meyer ◽  
G. R. Rossman
Keyword(s):  
Single Crystal ◽  
Structural Data ◽  
Crystal Structural Data ◽  
Crystal Structural

Monoclinic FeO at high pressures

2008 ◽  
Vol 223 (7/2008) ◽  
Author(s):  
Innokenty Kantor ◽  
Alexander Kurnosov ◽  
Catherine McCammon ◽  
Leonid Dubrovinsky
Keyword(s):  
High Pressure ◽  
Iron Oxide ◽  
Single Crystal ◽  
Diffraction Study ◽  
High Pressures ◽  
X Ray Diffraction ◽  
X Ray

AbstractA high-pressure quasi-single crystal X-ray diffraction study of a synthetic iron oxide Fe

Microporous crystal structure of labuntsovite-Fe and high-pressure behavior up to 23 GPa

2018 ◽  
Vol 74 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Sergey M. Aksenov ◽  
Elena A. Bykova ◽  
Ramiza K. Rastsvetaeva ◽  
Nikita V. Chukanov ◽  
Irina P. Makarova ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Single Crystal ◽  
Cross Section ◽  
Structure Refinement ◽  
Alkaline Complex ◽  
X Ray ◽  
Cell Parameters ◽  
Diamond Anvil ◽  
The Stability

Labuntsovite-Fe, an Fe-dominant member of the labuntsovite subgroup, was first discovered in the Khibiny alkaline massif on Mt Kukisvumchorr [Khomyakov et al. (2001). Zap. Vseross. Mineral. Oba, 130, 36–45]. However, no data are published about the crystal structure of this mineral. Labuntsovite-Fe from a peralkaline pegmatite located on Mt Nyorkpakhk, in the Khibiny alkaline complex, Kola Peninsula, Russia, has been investigated by means of electron microprobe analyses, single-crystal X-ray structure refinement, and IR and Raman spectroscopies. Monoclinic unit-cell parameters of labuntsovite-Fe are: a = 14.2584 (4), b = 13.7541 (6), c = 7.7770 (2) Å, β = 116.893 (3)°; V = 1360.22 (9) Å3; space group C2/m. The structure was refined to final R 1 = 0.0467, wR 2 = 0.0715 for 3202 reflections [I > 3σ(I)]. The refined crystal chemical formula is (Z = 2): Na2K2Ba0.7[(Fe0.5Ti0.1Mg0.05)(H2O)1.3]{[Ti2(Ti1.9Nb0.1)(O,OH)4][Si4O12]2}·4H2O. The high-pressure in situ single-crystal X-ray diffraction study of the labuntsovite-Fe has been carried out in a diamond anvil cell. The labuntsovite-type structure is stable up to 23 GPa and phase transitions are not observed. Calculations using the BM3 equation of state resulted in the bulk modulus K = 72 (2) GPa, K′0 = 3.7 (2) and V 0 = 1363 (2) Å3. Compressing of the heteropolyhedral zeolite-like framework leads to the deformation of main structural units. Octahedral rods show the gradual increase of distortion and the wave-like character of rods becomes more distinct. Rod deformations result in the distortion of the silicon–oxygen ring which is not equal in different directions. Structural channels are characterized by a different ellipticity–pressure relationship: the cross-section of the largest channel I and channel II demonstrates the stability of the geometrical characteristics which practically do not depend on pressure: ∊channel I ≃ 0.85 (4) (cross-section is rather regular) and ∊channel II ≃ 0.52 (2) within the whole pressure range. However, channel III is characterized by the increasing of ellipticity with pressure (∊ = 0.40 → 0.10).

scholarly journals Effect of HIP Parameters on the Micro-Structural Evolution of a Single Crystal Ni-Based Superalloy

2011 ◽  
Vol 278 ◽  
pp. 72-77 ◽  
Author(s):  
Inmaculada Lopez-Galilea ◽  
Stephan Huth ◽  
Marion Bartsch ◽  
Werner Theisen
Keyword(s):  
Single Crystal ◽  
Atmospheric Pressure ◽  
High Pressures ◽  
Hot Isostatic Pressing ◽  
Structural Evolution ◽  
Local Deformation ◽  
Local Distribution ◽  
Slow Cooling ◽  
Distribution Of Elements ◽  
Hardened State

For reducing the porosity of single crystal (SX) nickel-based superalloys, Hot Isostatic Pressing (HIP) is used. High pressures of about 100-170 MPa lead to local deformation, which close the pores. However, since HIP also requires high temperatures (1000-1200°C) it has a pronounced effect on the microstructure and the local distribution of elements. This contribution analyses the effect of different HIP treatments on both the microstructure and the segregation of the SX superalloy LEK94 in the as-precipitation-hardened state. In addition, the effects of rapid or slow cooling are analyzed. To distinguish the effect of pressure from those of temperature, the HIPed samples are compared with specimens annealed at atmospheric pressure.

scholarly journals Pressure Dependence of Structural and Mechanical Properties of Single-Crystal Tungsten: A Molecular Dynamics Study

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1898
Author(s):  
Xuepeng Liu ◽  
Kezhong Xu ◽  
Hua Zhai
Keyword(s):  
Mechanical Properties ◽  
Molecular Dynamics ◽  
High Pressure ◽  
Single Crystal ◽  
Pressure Dependence ◽  
High Pressures ◽  
External Pressure ◽  
Uniaxial Tensile ◽  
Linear Lattice ◽  
Lattice Contraction

In the current study, molecular dynamics (MD) simulations were performed to study the pressure dependence of the structural and mechanical properties of single-crystal tungsten. The results show that single-crystal tungsten possesses noteworthy high-pressure stability and exhibits linear lattice contraction with increasing external pressure. Consistent with the results of the performed experiments, the predicted elastic moduli, including Young’s modulus, shear modulus, and bulk modulus, as well as Poisson’s ratio and Pugh’s modulus ratio, show a clear increasing trend with the increase in pressure. Under uniaxial tensile loading, the single-crystal tungsten at high pressures experiences a phase transition from BCC to FCC and other disordered structures, which results in a stripe-like morphology in the tungsten crystal. These results are expected to deepen our understanding of the high-pressure structural and mechanical behaviors of tungsten materials.

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