General-purpose machine-learned potential for 16 elemental metals and their alloys.

Machine-learned potentials (MLPs) have exhibited remarkable accuracy, yet the lack of general-purpose MLPs for a broad spectrum of elements and their alloys limits their applicability. Here, we present a promising approach for constructing a unified general-purpose MLP for numerous elements, demonstrated through a model (UNEP-v1) for 16 elemental metals and their alloys. To achieve a complete representation of the chemical space, we show, via principal component analysis and diverse test datasets, that employing one-component and two-component systems suffices.

Pushing thermal conductivity to its lower limit in crystals with simple structures.

Materials with low thermal conductivity usually have complex crystal structures. Herein we experimentally find that a simple crystal structure material AgTlI (I4/mcm) owns an extremely low thermal conductivity of 0.25 W/mK at room temperature.

Mechanistic insight on water dissociation on pristine low-index TiO surfaces from machine learning molecular dynamics simulations.

Water adsorption and dissociation processes on pristine low-index TiO interfaces are important but poorly understood outside the well-studied anatase (101) and rutile (110). To understand these, we construct three sets of machine learning potentials that are simultaneously applicable to various TiO surfaces, based on three density-functional-theory approximations. Here we show the water dissociation free energies on seven pristine TiO surfaces, and predict that anatase (100), anatase (110), rutile (001), and rutile (011) favor water dissociation, anatase (101) and rutile (100) have mostly molecular adsorption, while the simulations of rutile (110) sensitively depend on the slab thickness and molecular adsorption is preferred with thick slabs.

Pressure effects on the anomalous thermal transport and anharmonic lattice dynamics of CsX (X = Cl, Br, and I).

The lattice thermal conductivity of CsX (X = Cl, Br, and I) and its pressure dependence are investigated using first-principles third-order anharmonic force constants. Contrary to the expectation that compounds with heavier atoms usually exhibit lower lattice thermal conductivity (), the of CsI is higher than those of CsCl and CsBr. This anomalous behavior is examined by analyzing the group velocity, phonon lifetime, three-phonon scattering phase space and Grüneisen parameters.

Leveraging bipolar effect to enhance transverse thermoelectricity in semimetal MgPb for cryogenic heat pumping.

Toward high-performance thermoelectric energy conversion, the electrons and holes must work jointly like two wheels of a cart: if not longitudinally, then transversely. The bipolar effect - the main performance restriction in the traditional longitudinal thermoelectricity, can be manipulated to be a performance enhancer in the transverse thermoelectricity. Here, we demonstrate this idea in semimetal MgPb.

Anharmonic lattice dynamics and thermal transport of monolayer InSe under equibiaxial tensile strains.

Two-dimensional (2D) InSe, which exhibits high electron mobility and a wide band gap has emerged as a promising material for photoelectric and thermoelectric applications. The inadequate understanding of the lattice thermal conductivity (), however, hampers the advancement of 2D InSe. Herein, by taking into account anharmonicity up to the fourth order and introducing the equibiaxial tensile strain (), we have performed an in-depth study on the lattice dynamics of 2D InSe.

Thermoelectric Enhancements in PbTe Alloys Due to Dislocation-Induced Strains and Converged Bands.

In-grain dislocation-induced lattice strain fluctuations are recently revealed as an effective avenue for minimizing the lattice thermal conductivity. This effect could be integratable with electronic enhancements such as by band convergence, for a great advancement in thermoelectric performance. This motivates the current work to focus on the thermoelectric enhancements of p-type PbTe alloys, where monotelluride-alloying and Na-doping are used for a simultaneous manipulation on both dislocation and band structures.

Manipulation of Band Degeneracy and Lattice Strain for Extraordinary PbTe Thermoelectrics.

Maximizing band degeneracy and minimizing phonon relaxation time are proven to be successful for advancing thermoelectrics. Alloying with monotellurides has been known to be an effective approach for converging the valence bands of PbTe for electronic improvements, while the lattice thermal conductivity of the materials remains available room for being further reduced. It is recently revealed that the broadening of phonon dispersion measures the strength of phonon scattering, and lattice dislocations are particularly effective sources for such broadening through lattice strain fluctuations.