Electrical switching of ferro-rotational order in nano-thick 1T-TaS2_2 crystals

Hysteretic switching of domain states is a salient character of all ferroic materials and the foundation for their multifunctional applications. Ferro-rotational order is emerging as a new type of ferroic order featuring structural rotations, but its controlled switching remains elusive due to its invariance under both time reversal and spatial inversion. Here, we demonstrate electrical switching of ferro-rotational domain states in nanometer-thick 1T-TaS$_2$ crystals in its charge-density-wave phases. Cooling from the high-symmetry phase to the ferro-rotational phase under an external electric field induces domain state switching and domain wall formation, realized in a simple two-terminal configuration using a volt-scale voltage. Although the electric field does not couple with the order due to symmetry mismatch, it drives domain wall propagation to give rise to reversible, durable, and nonvolatile isothermal state switching at room temperature. These results pave the path for manipulation of the ferro-rotational order and its nanoelectronic applications

Prediction of forming characteristics of titanium alloy self-locking nuts

Titanium alloy is an important class of aerospace material due to its high specific strength, excellent anti-corrosion and anti-oxidation. In this paper, a three-dimensional thermo-mechanical coupled simulation was carried out to predict the formation characteristics of TC4 titanium alloy self-locking nut during the upset forging process. The stability of the upset forging was analyzed, and the influences of initial temperature and deformation velocity on the formation quality were investigated. The results show that if length-diameter ratio of the sample less than 3.27, the upset forging formation tends to be stable, and here, the length-diameter ratio of 2.89 was selected. Additionally, the forming quality of TC4 self-locking nut improves with the increase of initial temperature and decreases with the increase of the velocity of the upper die. The analysis results can provide a theoretical guidance for the upset forging formation of TC4 titanium alloy nuts.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Numerical investigation of the effect of hole reaming on fatigue life by cold expansion

The reaming process of the 6061 aluminum alloy plate after cold expansion with split sleeve was simulated by finite element (FE) method based on Abaqus/CAE, the relationship between the reaming depths and the distribution of residual stress fields is obtained by analysis. The fatigue lives of the plate under different reaming depths were calculated by using the fatigue analysis software FE-SAFE, and verified by fatigue tests. The results show that reaming after expansion will increase the residual compressive stress at the hole edge on the entrance surface. In addition, the fatigue life of the specimens increases with the increase of the reaming depth, and the best fatigue gain of the specimen is obtained when the reaming depth of 0.5 mm.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Phthalazinone structure-based covalent triazine frameworks and their gas adsorption and separation properties

In this work, new classes of phthalazinone-based covalent triazine frameworks (PHCTFs) were prepared by ionothermal synthesis from two full rigid dicyano building blocks with rigid, thermostable and asymmetric N-heterocycle-containing structures. The surface and internal morphologies of PHCTFs were examined by FE-SEM and TEM. The resultant microporous polymers, PHCTFs, exhibited BET specific surface areas up to 1845 m(2) g(-1) and a moderately narrow pore size distribution. According to the sorption measurements, the CO2 uptake can be up to 17.1 wt% (273 K/1 bar) and the H-2 uptake can be up to 1.92 wt% (77 K/1 bar). Moreover, the initial slopes of the single component gas adsorption isotherms in the low pressure range were used as the gas separation ratios. The obtained polymer networks possess satisfactory CO2/N-2 selectivity performance up to 52 and CO2/CH4 selectivity up to 12. Combining the relationship of the structure and performance, it can be concluded that a twisted and non-coplanar topology conformation can be used to improve the porosity of microporous organic polymers. At the same time, the nitrogenand oxygen-rich characteristics of the phthalazinone core endow the networks with a strong affinity for CO2 and thereby high CO2 adsorption capacity. So the pore structure and chemical composition may play very important roles on the adsorption properties of small gas molecules