The refractory transition metal Rhenium (Re) is known to exist in a hexagonal close packed (hcp) phase right up to its high melting temperature of 3459 K and cubic phases have not been reported in rhenium rich alloys at ambient conditions. University of Alabama at Birmingham (UAB) researchers report on an unusual observation of pressure stabilized dual cubic phases in a high entropy alloy based on Re (https://journals.aps.org/prmaterials/abstract/10.1103/8smt-nygp). The structural… more

Researchers from the University of Houston and its Texas Center for Superconductivity collaborated with researchers from Argonne at the Advanced Photon Source to set a record superconducting transition temperature up to 151 K (at pressures in the range 10 – 30 GPa) in HgBa2Ca2Cu3O8+d. The more impressive part of this work is that they report a pressure quenching protocol (PQP) that allows them to quench the high-pressure phase to complete pressure release and record ambient-pressure high-temperature superconductivity. This nonequilibrium strategy for recovering novel… more

Understanding the kinetics of pressure-induced phase transformations requires experiments that can simultaneously control both pressure and temperature on timescales relevant to diffusional processes, typically 1 to 100 ms. While piezoelectrically driven dynamic diamond anvil cells (dDACs) excel at providing rapid, precisely controlled compression over many orders of magnitude in pressurization rate, their use at elevated temperatures has been severely limited by a geometric incompatibility: existing dDAC designs are too long to fit within the optical systems required for double-sided… more

High-entropy alloys have attracted growing attention due to their unusual phase stability, mechanical resilience, and emergent electronic properties under extreme conditions. While configurational entropy favors chemically disordered solid solutions, controlled pathways to introduce long-range chemical order in multicomponent alloys remain largely unexplored – particularly under simultaneous high pressure and high temperature.

In recent work, the high-pressure research group led by Prof. Yogesh K. Vohra at the University of Alabama at Birmingham (UAB) employed… more

In the recently published and highlighted work by Phys. Rev. B, the authors identified the thermodynamic mechanism behind the pressure-induced Invar effect in the Fe₆₈Pd₃₂ alloy, using synchrotron x-ray diffraction, nuclear resonant scattering, and neutron spectroscopy. Between 4 and 11 GPa, the material shows zero or negative thermal expansion as opposing contributions from phonon and magnetic entropies exactly cancel, even though each individually increases under pressure. The results reveal a small but measurable spin–phonon interaction (≈ 2 meV per atom) and demonstrate that the… more

Creating and understanding new permanent magnets requires an understanding effect of orbital angular momentum on coercivity. Permanent magnets are at the core of technologies ranging from energy generators to energy storage. The next generation of magnetic technology not only needs discovering new magnetic materials but also being able to tune the magnetic properties. Pressure enables tuning inter-atomic spacing and therefore their interactions much better than any other variable such as temperature or composition. Synchrotron based, in-situ measurements of structure and magnetic… more

High-entropy alloys (HEAs) have attracted significant interest due to their unconventional phase stability, mechanical robustness and superconducting properties. Configurational entropy (that increases with disordered atomic arrangement and lowers the overall free energy) is responsible for the stability of this class of materials and their unique response to applied uniaxial or hydrostatic pressures. 

In a first, a research team from the Center for Additively Manufactured Complex Systems under Extremes (CAMCSE), led by the University of Alabama at Birmingham, used… more

Ferroelectrics are very useful materials that interact strongly with electric fields, and have revolutionized, for only one example, medical ultrasound. New ferroelectrics have led to hand-held medical scanners, like in Star Trek, and have played significant role in increasing survival rates for battlefield casualties, lower infant mortality, and safety of the oceans through SONAR. In order to improve ferroelectrics, scientists must understand them. Whereas varying temperature or chemistry lead to complex changes in properties, applying pressure should be simpler to understand, as it… more