Pressure-Induced Exciton Formation and Superconductivity in Platinum-Based Mineral Sperrylite.

We report a comprehensive study of Sperrylite (PtAs), the main platinum source in natural minerals, as a function of applied pressures up to 150 GPa. While no structural phase transition is detected from pressure-dependent X-ray measurements, the unit cell volume shrinks monotonically with pressure following the third-order Birch-Murnaghan equation of state. The mildly semiconducting behavior found in pure synthesized crystals at ambient pressures becomes more insulating upon increasing the applied pressure before metalizing at higher pressures, giving way to the appearance of an abrupt decrease in resistance near 3 K at pressures above 92 GPa consistent with the onset of a superconducing phase.

Laser-Induced Thermal Decomposition of Uranium Coordination Compounds with Non-oxidic Ligands to Produce Nitride and Carbide Materials.

The production of ceramics from uranium coordination compounds can be achieved through thermal processing if an excess amount of the desired atoms (i.e., C or N), or reactive gaseous products (e.

Unconventional Pathways to Carbide Phase Synthesis via Thermal Decomposition of UI(1,4-dioxane).

UI(1,4-dioxane) was subjected to laser-based heating─a method that enables localized, fast heating ( > 2000 °C) and rapid cooling under controlled conditions (scan rate, power, atmosphere, etc.)─to understand its thermal decomposition. A predictive computational thermodynamic technique estimated the decomposition temperature of UI(1,4-dioxane) to uranium (U) metal to be 2236 °C, a temperature achievable under laser irradiation.

Semi-Automated Creation of Density Functional Tight Binding Models through Leveraging Chebyshev Polynomial-Based Force Fields.

Density functional tight binding (DFTB) is an attractive method for accelerated quantum simulations of condensed matter due to its enhanced computational efficiency over standard density functional theory (DFT) approaches. However, DFTB models can be challenging to determine for individual systems of interest, especially for metallic and interfacial systems where different bonding arrangements can lead to significant changes in electronic states. In this regard, we have created a rapid-screening approach for determining systematically improvable DFTB interaction potentials that can yield transferable models for a variety of conditions.

Interfacial-Redox-Induced Tuning of Superconductivity in YBaCuO.

Solid-state ionic approaches for modifying ion distributions in getter/oxide heterostructures offer exciting potentials to control material properties. Here, we report a simple, scalable approach allowing for manipulation of the superconducting transition in optimally doped YBaCuO (YBCO) films via a chemically driven ionic migration mechanism. Using a thin Gd capping layer of up to 20 nm deposited onto 100 nm thick epitaxial YBCO films, oxygen is found to leach from deep within the YBCO.

Contributed Review: Culet diameter and the achievable pressure of a diamond anvil cell: Implications for the upper pressure limit of a diamond anvil cell.

Recently, static pressures of more than 1.0 TPa have been reported, which raises the question: what is the maximum static pressure that can be achieved using diamond anvil cell techniques? Here we compile culet diameters, bevel diameters, bevel angles, and reported pressures from the literature. We fit these data and find an expression that describes the maximum pressure as a function of the culet diameter.

Pressure-Resistant Intermediate Valence in the Kondo Insulator SmB_{6}.

Resonant x-ray emission spectroscopy was used to determine the pressure dependence of the f-electron occupancy in the Kondo insulator SmB_{6}. Applied pressure reduces the f occupancy, but surprisingly, the material maintains a significant divalent character up to a pressure of at least 35 GPa. Thus, the closure of the resistive activation energy gap and onset of magnetic order are not driven by stabilization of an integer valent state.