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Softening of the heat-affected zone degrades the mechanical properties of high-strength steel-welded joints. This work revealed the key mechanism to suppress the adverse effects of the soft zone on joint performance by analyzing the constraint between different zones. The base metal (BM) can compete with the soft zone for plastic deformation when the soft zone is strongly constrained by the hard zone, which helps to disperse local strain and prevent premature necking. The constraint mode of the soft zone tends to evolve asymmetrically from bilateral to unilateral during the deformation. Reducing the width of the soft zone helps to achieve unilateral constraint, thus shifting the fracture location from the soft zone to the BM. [ABSTRACT FROM AUTHOR]

Abstract: Aluminum hydroxides are considered to be a potential abundant, low‐cost blue emissive material to construct UV‐pumped white light‐emitting diodes (WLEDs). In this work, a single‐source precursor chemical vapor decomposition method is adapted to fabricate stable, strongly emissive aluminum hydroxide phosphors with photoluminescence quantum yield of up to 69% in solid state by thermal decomposing aluminum diacetate hydroxide (Al(OH)(Ac)2) at temperatures (260–360 °C) in N2 atmosphere. It exhibits layered, amorphous structure and its emission of aluminum hydroxide is enhanced by electron‐donating surface hydroxyl groups and originates from F+ centers and carbon‐related defects contributing to UV (388 nm) and blue (450–520 nm) spectral regions, respectively. Employing the as‐fabricated aluminum hydroxides as blue phosphor and CuInS2 nanocrystals as red phosphor, high color rendering and high‐efficiency WLEDs with luminous efficiencies up to 37 lm W−1 and high color rendering index of 91 are fabricated. This is the best performance reported so far for aluminum hydroxide based LEDs. [ABSTRACT FROM AUTHOR]

Perovskite semiconductor materials have attracted significant attention in the fields of photovoltaics and luminescence due to their excellent photoelectric properties, such as high carrier mobility, high absorption coefficient, and high fluorescence quantum yield. In particular, low-dimensional metal-halide perovskite microcrystalline materials have been reported to exhibit low-dimensional lasing phenomena and laser devices due to their high gain and widely tunable bandgap. In this Letter, one-dimensional (1-D) ZnO microwires with their ultraviolet lasing emissions are utilized as an excitation source to pump CsPbBr 3 microwire on hybrid ZnO-CsPbBr 3 microscale structures. At higher excitation, the amplified spontaneous emission (ASE) behaviors from CsPbBr 3 microwire are realized with ultralow threshold by indirect pumping from the ZnO lasing emission for the first time, to the best of our knowledge. In comparison, the ASE behaviors from the CsPbBr 3 microwire directly pumped by Nd:YAG Q-switched laser and continuous wave laser are also performed at room temperature. There are also no multimode lasing behaviors observed. The paper provides a new method to achieve a low threshold on-chip microlaser by a high-quality perovskite micro-nano structure.

Electrically pumped halide perovskite laser diodes remain unexplored, and it is widely acknowledged that continuous-wave (CW) lasing will be a crucial step. Here, we demonstrate room-temperature amplified spontaneous emission of Fe-doped CsPbBr 3 crystal microwire excited by a CW laser. Temperature-dependent photoluminescence spectra indicate that the Fe dopant forms a shallow level trap states near the band edge of the lightly doped CsPbBr 3 microcrystal. Pump intensity-dependent time-resolved PL spectra show that the introduced Fe dopant level makes the electron more stable in excited states, suitable for the population inversion. The emission peak intensity of the lightly Fe-doped microwire increases nonlinearly above a threshold of 12.3 kW/cm 2 under CW laser excitation, indicating a significant light amplification. Under high excitation, the uniform crystal structure and surface outcoupling in Fe-doped perovskite crystal microwires enhanced the spontaneous emission. These results reveal the considerable promise of Fe-doped perovskite crystal microwires toward low-cost, high-performance, room-temperature electrical pumping perovskite lasers.

Nanoscale heterostructures, which incorporate two or more materials such as core-shell nanocrystals, core-crown nanoplates, or seeded nanorods, allow better control of the optical, electrical and magnetic properties that are inaccessible in single component nanostructure, yet their variety and controlled growth are still challenging. Here, a nail-like Mn-doped CdS/CdBr 2 hetero-nanostructure, which has a hexagonal plate on top of a nanowire, is firstly fabricated by a simple one-step thermal evaporation process. According to the characterization results, its growth mechanism could be obtained, in which the manganese bromide precursor plays a critical role in the formation of such nail morphology. The amplified spontaneous emission of the 'nanonail' is achieved at a low threshold at room temperature, which come from the local and dense exciton scattering due to their interactions excited by fs pulse. These interesting nail-like heterostructures may provide promising templates for constructing high-performance optoelectronic devices.