THE COPPER/ARSENIC SYSTEM AND THE COPPER ARSENIDE MINERALS

1960 ◽  
Vol 38 (12) ◽  
pp. 2477-2481 ◽  
Author(s):  
R. D. Heyding ◽  
G. J. G. Despault
Keyword(s):  
Solid Solution ◽  
High Pressure ◽  
Approximate Formula ◽  
Text Structure ◽  
Intermediate Phases ◽  
Ε Phase ◽  
Polymorphic Forms ◽  
Copper Arsenide ◽  
Pressure Phase ◽  
Copper Arsenic

In addition to the α solid solution of arsenic in copper, three intermediate phases exist in the copper/arsenic system. The ε phase, stable only below ca. 340 °C, has the hexagonal A3 [Formula: see text] structure with a = 2.588, c = 4.226 Å, and the approximate formula Cu8As. The compound Cu3−xAs with 0 ≤ x ≤0.3, is trigonal, [Formula: see text]with a = 7.132, c = 7.304 Å at x = 0. This compound has no polymorphic forms between 200 °C and the melting point. The arsenic-rich compound Cu5−uAs2, with 0 ≤ u ≤ 0.1, melts incongruently at about 700 °C, and decomposes at 300 °C to arsenic and Cu3As. The structure has not been determined, but the powder diffraction pattern is recorded. The solubility of copper in arsenic appears to be negligible.It is suggested that the mineral α domeykite is a high-pressure phase, and that the mineral algodonite is a high-pressure modification of the ε phase. The mineral β domeykite is isostructural with Cu3As.

Femtosecond Laser Synthesis of the High-Pressure Phase of Iron

2006 ◽  
Vol 512 ◽  
pp. 349-354
Author(s):  
Tomokazu Sano ◽  
Osamu Sakata ◽  
Etsuji Ohmura ◽  
Isamu Miyamoto ◽  
Akio Hirose ◽  
...  
Keyword(s):  
Shock Wave ◽  
High Pressure ◽  
Femtosecond Laser ◽  
X Ray Diffraction ◽  
X Ray ◽  
Α Phase ◽  
Iron Sample ◽  
Ε Phase ◽  
Pressure Phase ◽  
Fcc Structure

The synthesis of the high-pressure ε phase of iron, which has not been observed under a conventional shock compression, was attained using a femtosecond laser. The lower pressure and temperature α phase (bcc) transforms to the γ phase (fcc) at higher temperatures and to the ε phase (hcp) at higher pressures. A shock induced α to ε phase transition in iron is one of the most famous transitions under high pressure. The induced high-pressure ε phase by a conventional shock loading returns to the α phase and it is not quenched after the shock release because this transition is considered to be diffusionless. Crystalline structures in a recovered iron sample after the femtosecond laser (800 nm, 120 fs, 1014 W/cm2) irradiation were determined using the electron diffraction and the synchrotron X-ray diffraction methods. These results show the existence of the ε phase and the fcc structure in the recovered iron. The femtosecond laser-driven shock wave may have the potential to synthesis high-pressure phases of other materials that has not been done using the conventional shock wave.

Formation of Ni80P20 solid solution phase under high pressure

1994 ◽  
Vol 9 (8) ◽  
pp. 1927-1928
Author(s):  
Z.L. Mao ◽  
H. Chen ◽  
Ai-Lien Jung
Keyword(s):  
Solid Solution ◽  
High Pressure ◽  
Solid Solutions ◽  
High Pressure Phase ◽  
Solution Phase ◽  
Solid Solution Phase ◽  
Amorphous Phases ◽  
Supersaturated Solid Solutions ◽  
Quenching Method ◽  
Pressure Phase

A Ni-P solid-solution phase was obtained by quenching from the melt under a pressure of 4.5 GPa. It was considered as a metastable high-pressure phase. Metastable phases with the same composition as the melt, such as supersaturated solid solutions and amorphous phases, are easily prepared using a high pressure quenching method.

First-principles studies of phase transition and structural stability of SrC2 under pressure

2014 ◽  
Vol 28 (24) ◽  
pp. 1450190 ◽  
Author(s):  
Yi-Lin Lu ◽  
Hui Zhao
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
First Principles ◽  
Phonon Dispersion ◽  
Covalent Bond ◽  
Text Structure ◽  
High Pressure Phase ◽  
Space Group ◽  
Type Space ◽  
Pressure Phase

Pressure-induced phase transitions in SrC 2 are investigated using the first-principles plane wave pseudopotential method within the generalized gradient approximation. The phase transition from monoclinic phase ( CaC 2-II-type, space group C2/c) to trigonal ( CaC 2-VII-type, space group [Formula: see text]) structure is predicted to occur at 10.4 GPa. The high-pressure phase is thermodynamic, mechanically and dynamically stable, as verified by the calculations of its formation energy, elastic stiffness constants and phonon dispersion. Further the electronic analysis predicates this high-pressure phase to be an insulator. When increasing pressure, the ionic bond between C and Sr is strengthened, as well is the covalent bond between C and C , however, the increase of the ionic interaction between Sr and C preponderates over that of the covalent bond interaction, so the gap is narrowed.

High-pressure Cu–Fe–S Phase Equilibria: some Experimental and Thermodynamic Constraints on Sulfides in Subduction Zones and the Lithospheric Mantle

2020 ◽  
Vol 61 (4) ◽  
Author(s):  
Julie L Brown ◽  
Sabastien C Dyer ◽  
James E Mungall ◽  
Andrew G Christy ◽  
David J Ellis
Keyword(s):  
Solid Solution ◽  
High Pressure ◽  
Lithospheric Mantle ◽  
Subduction Zones ◽  
Experimental Studies ◽  
Low Pressure ◽  
Sulfide Mineral ◽  
Phase Relations ◽  
Mineral Inclusion ◽  
Pressure Phase

Abstract High-pressure phase relations for much of the Cu–Fe–S system have not previously been determined experimentally. Experimental studies have concentrated on low-pressure phase relations and cannot explain high-pressure sulfide mineral inclusion assemblages in some natural blueschists and eclogites. In particular, the coexistence of pyrite + covellite at 1·0 GPa, and pyrite + bornite at 1·9 GPa, observed in New Caledonian rocks, is precluded by tie-lines between S and bornite, and S and the intermediate solid solution (iss), in the published low-pressure experimental topologies at corresponding temperatures. In addition, the Cu content (up to ∼10 at%) of pyrrhotite in eclogite exceeds the experimentally determined maximum for Cu in solid solution with pyrrhotite at low pressures and at corresponding temperatures. We have performed six experiments in which natural chalcopyrite starting material was equilibrated at conditions ranging from 1·0 to 1·7 GPa and 500 to 650 °C. At 1 GPa chalcopyrite is replaced by iss. The iss phase undergoes a terminal breakdown reaction between 1·0 and 1·7 GPa, being replaced by a new assemblage of bornite, pyrite, and pyrrhotite. Our experimental results confirm predictions from the SUPCRT thermodynamic database (Johnson et al., 1992; Computers & Geosciences 18, 899–947) but not that of Robie & Hemingway (1995; US Geological Survey Bulletin 2131). The former database is therefore recommended for calculation of high-pressure sulfide phase relations. Chalcopyrite and its high-temperature, low-fS2 equivalent, iss are not stable at pressures corresponding to much of blueschist–eclogite-facies metamorphism. These results are also applicable to sulfide assemblages in the lithospheric mantle along both oceanic and continental geotherms; the subsolidus Cu-rich mineral in the lithosphere at depths of 30 to >65 km must be bornite–digenite solid solution (bn-ss) rather than iss as is commonly assumed.

High-pressure phase transitions of Fe3-xTixO4 solid solution up to 60 GPa correlated with electronic spin transition

2013 ◽  
Vol 98 (4) ◽  
pp. 736-744 ◽  
Author(s):  
T. Yamanaka ◽  
A. Kyono ◽  
Y. Nakamoto ◽  
Y. Meng ◽  
S. Kharlamova ◽  
...  
Keyword(s):  
Solid Solution ◽  
High Pressure ◽  
Phase Transitions ◽  
Spin Transition ◽  
High Pressure Phase ◽  
Electronic Spin ◽  
Pressure Phase

scholarly journals Crystal and electronic structure engineering of tin monoxide by external pressure

2021 ◽  
Author(s):  
Kun Li ◽  
Junjie Wang ◽  
Vladislav A. Blatov ◽  
Yutong Gong ◽  
Naoto Umezawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
High Pressures ◽  
Low Pressure ◽  
Widespread Application ◽  
Space Group ◽  
Tin Monoxide ◽  
High Possibility ◽  
Pressure Phase

AbstractAlthough tin monoxide (SnO) is an interesting compound due to its p-type conductivity, a widespread application of SnO has been limited by its narrow band gap of 0.7 eV. In this work, we theoretically investigate the structural and electronic properties of several SnO phases under high pressures through employing van der Waals (vdW) functionals. Our calculations reveal that a metastable SnO (β-SnO), which possesses space group P21/c and a wide band gap of 1.9 eV, is more stable than α-SnO at pressures higher than 80 GPa. Moreover, a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 120 GPa. Energy and topological analyses show that P2/c-SnO has a high possibility to directly transform to β-SnO at around 120 GPa. Our work also reveals that β-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase α-SnO for the phase transition path Pnma-SnO →β-SnO → α-SnO. Two phase transition analyses indicate that there is a high possibility to synthesize β-SnO under high-pressure conditions and have it remain stable under normal pressure. Finally, our study reveals that the conductive property of β-SnO can be engineered in a low-pressure range (0–9 GPa) through a semiconductor-to-metal transition, while maintaining transparency in the visible light range.

scholarly journals The Enrichment of (Cu, Sn) Solid Solution Driven by High-Pressure Torsion

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 766
Author(s):  
Boris Straumal ◽  
Askar Kilmametov ◽  
Anna Korneva ◽  
Pawel Zięba ◽  
Yuri Zavorotnev ◽  
...  
Keyword(s):  
Solid Solution ◽  
High Pressure ◽  
Theoretical Analysis ◽  
Annealing Temperature ◽  
High Pressure Torsion

Cu–14 wt% Sn alloy was annealed at temperatures of 320 and 500 °C. The concentration of tin cinit in the copper-based matrix increased with annealing temperature. The annealed samples were subjected to high-pressure torsion (HPT) at 6 GPa, 5 turns, 1 rpa. HPT led to the refinement of Cu grains. The shape of the colonies of α + ε phases changed only slightly. The HPT-driven enrichment of the Cu-based solid solution with Sn atoms cHPT–cinit decreased with increasing cinit. The performed theoretical analysis explained this behavior of the HPT-driven enrichment.

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