Thermoelectric technology allows conversion between heat and electricity. Many good thermoelectric materials contain rare or toxic elements, so developing low-cost and high-performance thermoelectric materials is warranted. Here, we report the temperature-dependent interplay of three separate electronic bands in hole-doped tin sulfide (SnS) crystals. This behavior leads to synergistic optimization between effective mass (m*) and carrier mobility (μ) and can be boosted through introducing selenium (Se). This enhanced the power factor from ~30 to ~53 microwatts per centimeter per square kelvin (μW cm−1 K−2 at 300 K), while lowering the thermal conductivity after Se alloying. As a result, we obtained a maximum figure of merit ZT (ZTmax) of ~1.6 at 873 K and an average ZT (ZTave) of ~1.25 at 300 to 873 K in SnS0.91Se0.09 crystals. Our strategy for band manipulation offers a different route for optimizing thermoelectric performance. The high-performance SnS crystals represent an important step toward low-cost, Earth-abundant, and environmentally friendly thermoelectrics.

In the present study, an attempt was made to join two dissimilar light metal alloys which are becoming increasingly familiar in the automotive industry, i.e. AA5083 aluminium alloy and AZ31 magnesium alloy, by the friction stir spot welding process. Lap welds were produced with various welding parameters, and interfacial microstructures and lap shear strengths of these welds were examined. Friction stir spot welding produced defect-free welds, even though a thick interfacial layer composed mainly of intermetallic compounds was present. The thickness of the interfacial layer did not appear to affect the lap shear strength of the weld, whereas the distribution of intermetallic compounds in the interfacial layer did so. Microstructural factors of the interface governing the lap shear strength of the weld were examined.

Among first experimentally discovered two-dimensional (2D) ferromagnetic materials, chromium triiodide (CrI 3 ) monolayers have attracted particular attention due to their potential applications in electronics and spintronics. However, the Curie temperature T c of the CrI 3 monolayer is below room temperature, which greatly limits practical development of the devices. Herein, using density functional theory calculation, we explore how the electronic and magnetic properties of CrI 3 monolayers change upon adsorption of 3d transition-metal (TM) atoms (from Sc to Zn). Our results indicate that the electronic properties of the TM−CrI 3 system can be tuned from semiconductor to metal/half-metal/spin gapless semiconductor depending on the choice of the adsorbed TM atoms. Moreover, the adsorption can improve the ferromagnetic stability of CrI 3 monolayers by increasing both magnetic moments and T c . Notably, T c of CrI 3 with Sc and V adatoms can be increased by nearly a factor of 3. We suggest postsynthesis doping of 2D CrI 3 by deposition of TM atoms as a new route toward potential applications of TM−CrI 3 systems in nanoelectronic and spintronic devices.

To suppress charge injection from electrodes, direct fluorination using fluorine gas was used for linear low density polyethylene (LLDPE) since it is one of the most effective methods of the polymer surface modification. Surface fluorination of the LLDPE plates was obtained as indicated by attenuated total reflection infrared spectroscopy. Remarkable suppression of charge injection by the surface fluorination was observed by space charge distribution measurements using the pressure wave propagation method. Comparing with the remarkable bipolar charge distribution in bulk of the original LLDPE, there is less space charge in bulk and it mostly exists in the fluorinated surface layers. The possible mechanisms of the charge injection suppression are discussed, one of which, the effect of fluorination on the charge traps in surface layer was investigated by the thermally stimulated discharge technique. The results indicate that fluorination has charge traps in the surface layer remarkably deepened and charges captured in the deep traps can block or shield the further charge injection.