Materials Today Physics最新文献

Recently, Zintl Mg₃Sb₂-based compounds have attracted attention due to high thermoelectric performance, but most studies are concentrated on bulk materials with few on films and devices, limiting their applications for microelectronics. Here, p-type Mg₃Sb₂ films near stoichiometric-ratio are successfully fabricated using the multi-step experimental strategies based on the magnetron sputtering method. By tuning the energy structure and carrier transport, their thermoelectric performance is significantly improved, with a power factor up to 258.64 μW m⁻¹ K⁻² at ∼623 K. A Mg₃Sb₂-based generator is fabricated using these films, representing the first report of such a device. The output performance of this generator is evaluated and its power density is found to reach 9.4 μW cm⁻² at ΔT of 40 K, showing good potential for powering electronics. Furthermore, the generator shows good stability with no significant change in output properties after storage in air for 40 days or over periodic cycles of high- and room-temperature operation.

In-situ diffuse neutron scattering experiments revealed that when electric current is passed through single crystals of rutile TiO₂ under conditions conducive to flash sintering, it induces the formation of parallel planes of oxygen vacancies. Specifically, a current perpendicular to the c-axis generates planes normal to the (132) reciprocal lattice vector, whereas currents aligned with the c-axis form planes normal to the (132) and to the (225) vector. The concentration of defects increases with incresing current. The structural modifications are linked to the appearance of signatures of interacting Ti³⁺ moments in magnetic susceptibility, signifying a structural collapse around the vacancy planes. Electrical conductivity measurements of the modified material reveal several electronic transitions between semiconducting states (via a metal-like intermediate state) with the smallest gap being 27 meV. Pristine TiO₂ can be restored by heating followed by slow cooling in air. Our work suggests a novel paradigm for achieving switching of electrical conductivity related to the flash phenomenon.

Lattice thermal conductivity (κ_L) is a crucial physical property of crystals with applications in thermal management, such as heat dissipation, insulation, and thermoelectric energy conversion. However, accurately and rapidly determining κ_L poses a considerable challenge. In this study, we introduce a formula that achieves high precision (mean relative error = 8.97 %) and provides fast predictions, taking less than 1 min, for κ_L across a wide range of inorganic binary and ternary materials. Our interpretable, dimensionally aligned and physical grounded formula forecasts κ_L values for 4601 binary and 6995 ternary materials in the Materials Project database. Notably, we predict undiscovered high κ_L values for AlBN₂ (κ_L = 101 W m⁻¹ K⁻¹) and the undetected low κ_L Cs₂Se (κ_L = 0.98 W m⁻¹ K⁻¹) at room temperature. This method for determining κ_L streamlines the traditionally time-consuming process associated with complex phonon physics. It provides insights into microscopic heat transport and facilitates the design and screening of materials with targeted and extreme κ_L values through the application of phonon engineering. Our findings offer opportunities for controlling and optimizing macroscopic transport properties of materials by engineering their bulk modulus, shear modulus, and Grüneisen parameter.

Hydrate method to capture and store CO₂ under sea floor as one of the most novel and promising methods to deal with the greenhouse effect and reduce carbon emission has gained increasing attention nowadays. But how to grow CO₂ hydrate under promotion in confinement has rarely been exploited. Here the growth of CO₂ hydrate with tetrahydrofuran (THF) promoter in confinement was systematically investigated by molecular dynamics simulations, with the counterpart growth but without promoter as a comparison. With promoter, an obviously more rapid growth of CO₂ hydrate was observed and CO₂ molecules went inside water cages along with the THF ones but not gathered into bubbles during the formation of clathrate. However, the gathering of CO₂ bubbles in the system without promotion hindered the obvious formation of clathrate. The vivid movies and physical quantities were analyzed in detail in order to further unravel the physical mechanism of the growth process and the promotion effect of THF. The obtained simulation results proved that THF could indeed promote the confined growth of CO₂ hydrate by preventing the formation of large CO₂ bubbles, providing a theoretical foundation for the geological storage of CO₂ hydrate in permafrost areas and marine sediments.