We report an alumina-encapsulated microcircuit on a diamond anvil for high-pressure and high-temperature electrical conductivity measurement. An alumina thin film was deposited on a diamond anvil as a thermal insulation layer for laser heating, on which a molybdenum film was deposited and photolithographically fabricated to a van der Pauw circuit. The introduction of the alumina layer significantly improves the laser heating performance. This specially fabricated diamond anvil permits us to measure the resistivity of (Mg0.875Fe0.125)2SiO4 at 3450K and 35GPa in a laser-heated diamond anvil cell. We expect to substantially extend the pressure-temperature scale of in situ resistivity measurement.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Fe-substituted materials SrFe1+xMo1-xO6-delta (x = 0, 0.1, 0.2, 0.3, 0.4) were synthesized by a modified polymer-network gel method at a relatively low temperature. The structural stability and electrical properties of Sr2FeMoO6 and Sr2Fe1.4Mo6-delta have been studied using energy dispersive X-ray diffraction with synchrotron radiation and resistance and capacitance measurements, respectively. The results show that the crystal structure of Sr2Fe1.4Mo0.6O6-delta is as stable as Sr2FeMoO6 at high pressure and more compressible than Sr2FeMoO6. On the basis of the measurements of resistance and capacitance versus pressure, it is considered that they all undergo an electronic structure transition under high pressure. (C) 2004 Elsevier B.V. All rights reserved.
Mg3Bi2–xSbx (0 ≤ x ≤ 2) have gained significant attention due to their potential in thermoelectric (TE) applications. However, there has been much debating regarding their structural properties and phase diagram as a function of pressure, which is crucial for understanding of their TE properties. Here, we investigate a unified phase diagram of Mg3(Bi,Sb)2 materials up to 40 GPa at room temperature using high-pressure X-ray diffraction. Two high-pressure phases with the structural transition succession of P3¯m1 → C2/m → P21/n are observed, which is valid for all Mg3Bi2–xSbx (0 ≤ x ≤ 2) compounds. We further explore the low-pressure phase P3¯m1 and report that alloying does not change the quasi-isotropic compression of the unit lattice parameters nor has effect on the anisotropic bond compressibility, as recently reported for the end-members. Our study presents a comprehensive picture of Mg3Bi2–xSbx as a function of pressure and chemical composition providing a solid foundation for the future experimental and theoretical studies searching for the most efficient TE compound in Mg3(Bi,Sb)2.
The deformation mechanisms of nanotwinned Cu subjected to nanoscratching are investigated by means of molecular dynamics simulations. Scratching simulations on nanotwinned single-crystalline Cu with the twin planes parallel and perpendicular to the scratching direction are performed. Since the detwinning mechanism is completely suppressed in the former case, no apparent correlation between frictional coefficient and the twin spacing is observed. In samples where the twin planes are perpendicular to the scratching direction, the friction increases as the twin spacing decreases, and then decreases as the twin spacings become even smaller. It results from the competitive plastic deformation between the inclined dislocations and the detwinning mechanism. Subsequent simulations for nanotwinned polycrystalline Cu unveil that in addition to the grain-boundary-associated deformation mechanism, dislocation-mediated detwinning plays a significant role in the plastic deformation of nanotwinned Cu. The twin boundary spacing in turn affects nanotwinned materials to resist scratching via plastic deformation. We demonstrate via the nanoscratching tests that there exists a critical twin boundary spacing for which the friction coefficient is maximized and that this transition results from the competing deformation mechanisms in those nanotwinned materials.
Abstract Metal halide perovskite quantum dots (QDs) have garnered tremendous attention in optoelectronic devices owing to their excellent optical and electrical properties. However, these perovskite QDs are plagued by pressure‐induced photoluminescence (PL) quenching, which greatly restricts their potential applications. Herein, the unique optical and electrical properties of Eu 3+ ‐doped CsPbCl 3 QDs under high pressure are reported. Intriguingly, the PL of Eu 3+ ions displays an enhancement with pressure up to 10.1 GPa and still preserves a relatively high intensity at 22 GPa. The optical and structural analysis indicates that the sample experiences an isostructural phase transition at approximately 1.53 GPa, followed by an amorphous state evolution, which is simulated and confirmed through density functional theory calculations. The pressure‐induced PL enhancement of Eu 3+ ions can be associated with the enhanced energy transfer rate from excitonic state to Eu 3+ ions. The photoelectric performance is enhanced by compression and can be preserved upon the release of pressure, which is attributed to the decreased defect density and increased carrier mobility induced by the high pressure. This work enriches the understanding of the high‐pressure behavior of rare‐earth‐doped luminescent materials and proves that high pressure technique is a promising way to design and realize superior optoelectronic materials.
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