Solution peeling of perovskite single crystals for the fabrication of stable and highly efficient phosphors.

Different gradient architectures produce distinct Al/Nb redistribution pathways, which govern heterogeneous segregation, lattice strain evolution, and ultimately the mechanical performance of Ti60/Ti2AlNb functionally graded materials (FGMs). In this work, Ti60/Ti2AlNb FGMs with direct, single-gradient, and triple-gradient transition strategies were fabricated by laser melting deposition. The direct and triple-gradient transitions developed Al- and Nb-rich segregation regions, whereas the single-gradient transition induced uphill diffusion of Al and Nb, effectively suppressing segregation. Multiphysics simulations indicated that melt-pool convection and repeated remelting continuously redistributed Al and Nb during deposition, promoting the experimentally observed uphill diffusion and reducing local solute enrichment. High-energy X-ray diffraction revealed lattice strain concentration in the dilution zone of the direct transition and the O-phase strain localization in the triple-gradient transition, while the single-gradient transition exhibited the most homogeneous lattice strain distribution. Consequently, the single-gradient transition achieved the best strength-ductility combination, with an ultimate tensile strength of 1120.4 ± 12.7 MPa, a yield strength of 1057.5 ± 8.1 MPa, and an elongation of 4.10 ± 0.46%. Near-fracture microstructure analyses showed that heterogeneous segregation promoted deformation incompatibility, and dense acicular α’ martensite formed in the triple-gradient transition further reduced local microstructural stability, whereas dispersed nanoscale precipitates and abundant stacking faults in the single-gradient transition facilitated uniform strain partitioning. These findings provide new insight into the design of additively manufactured Ti/TiAl FGMs.

Perovskite materials have attracted substantial attention for their promising applications in high-performance light-emitting devices. However, the development of cyan-emissive metal halide perovskites lags markedly behind their red and green counterparts among the multi-color emissive type perovskites, primarily because of their poor stability and low luminescence efficiency. Herein, PbBr(OH)-encapsulated and Zn-doped MAPbBrxCl3-x (MA = CH3NH3+) cyan phosphors were fabricated by in situ solution peeling from Zn-alloyed MAPbBrxCl3-x single crystals. Notably, the PbBr(OH) shell-encapsulated perovskite phosphors not only demonstrate excellent stability under light, heat, and exposure to organic solvents but also confine the photogenerated excitons, passivate surface defects, prevent ion migration and suppress non-radiative losses in the MAPbBrxCl3-x nanocrystals upon Zn doping, resulting in a high photoluminescence quantum yield (PLQY). As a representative candidate, the Zn:MAPbBr2.2Cl0.8@PbBr(OH) phosphor exhibits a bright cyan emission at 481 nm with a high PLQY of over 90%. The Zn:MAPbBr2.2Cl0.8@PbBr(OH) phosphor-based cyan light-emitting diode maintains a brightness exceeding 1000 cd m-2 even after 24 h of continuous operation under a current of 9.8 mA with exceptional stability. Furthermore, these cyan-emissive phosphors can be utilized for overcoming the issues of "blue overshoot" and "cyan gap" in white light-emitting diodes.

Mixed halide perovskite CsPbBrxI3-x nanocrystal (NC) films exhibit viable application prospects in pure red perovskite light-emitting diodes (PeLEDs). However, intrinsic environmental instability, defects, and spectral instabilities are always present in pure red perovskites under mixing halide ion exchange processing. In this work, we developed a swelling method for the preparation of stable pure red light emission Zn: CsPbBrxI3-x-PVDF films by post-treatment with CsBr-ZnI2 at room temperature. In this system, PVDF-CsBr-ZnI2 presents triple synergistic effects to control anion exchange, stabilize the crystal structure, and passivate the defects of the red CsPbBrxI3-x-PVDF film, simultaneously. In addition, the Zn: CsPbBrxI3-x-PVDF films' photoluminescence emission can be precisely tuned from 665 to 580 nm with high spectral stability. More importantly, the as-prepared 637 nm emitting Zn: CsPbBrxI3-x-PVDF films present a full width at half-maximum (fwhm) as narrow as 50 nm with a high photoluminescence quantum yield (PLQY) of more than 47.27% after annealing. It was also demonstrated to serve as conversion layers for stable pure red LEDs, achieving the CIE Rec. 2020 standard and sustained electrical stability. The trinity of halide exchange, Zn passivation, and polymer encapsulation provides a novel strategy for obtaining high-quality perovskite lighting flexible thin films.

Most existing intelligent fault diagnosis methods rely primarily on signals collected from a single sensor, while the complementary information embedded in multi-sensor measurements is often overlooked, leading to limited diagnostic performance. To address this issue, this study investigates the effectiveness of improving classification accuracy through the fusion of complementary features derived from multiple sensors. Specifically, a novel intelligent fault diagnosis framework that integrates Multi-Sensor Fusion (MSF) with a Multi-Scale Residual Convolutional Neural Network (MS-ResCNN) is presented. First, a principal component analysis (PCA)-based multi-signal fusion strategy is applied to transform multi-sensor signals into three-channel continuous wavelet transform (CWT) images, enabling rich time-frequency feature representation. Subsequently, an enhanced multi-scale convolutional architecture with residual connections is designed to strengthen feature extraction and improve diagnostic reliability. Experimental results on the KAT dataset verify that the proposed method outperforms several state-of-the-art deep learning approaches in fault identification accuracy, while also demonstrating strong robustness and generalization ability.

Nowadays, most solid-state lighting-based visible light communication (VLC) technology suffers from the color converter's short optical bandwidth or low stability. Herein, we fabricated MAPbBr3@PbBr(OH) nanocrystals (NCs) with high optical bandwidth and water-stable properties for color conversion of VLC and a white light-emitting diode (LED) system. The sample's characteristic photoluminescence (PL) spectrum is green emission peaked near 529 nm. As a color converter, it has a high bandwidth capacity for devices. The sample indicates internal quantum efficiency (IQE) of about 38.33% and a PL decay time of about 5.5 ns, and it can maintain its PL properties in water for over 90 days The calculated optical bandwidth is about 49.4 MHz. Its measured -3 dB bandwidth with a 405 nm laser diode can reach 25 MHz with a data rate over 50 Mbps. More interestingly, the perovskite NCs can replace the green phosphor to build a high-speed and multicolor LED, and the -3 dB bandwidth can be maintained at over 80% in this case. These features are far beyond the abilities of commercial green phosphors. Finally, we demonstrate an underwater text transmission system with a 405 nm LED, perovskite color conversion layer, and low-cost silicon-based photodetector.

The present study involved (TiB + TiC)/TC11 (Ti-6.5Al-3.5Mo-1.2Zr-0.3Si) + xFe titanium matrix composites (TMCs) reinforced by in situ TiB whiskers and TiC particles fabricated by hot isostatic pressing. Microstructure observation reveals a substantial distribution of in situ reinforcements, which form a network-reinforced structure at the prior particle boundaries of the TC11 matrix. The micro–nanoscale TiB whiskers and TiC particles within and surrounding this network serve as effective dislocation pinning. The enhancement of mechanical properties can be attributed to load-bearing strengthening, fine-grain strengthening, and dislocation strengthening. The hardness and compressive strengths were investigated through mechanical properties testing. The hardness increased by 19.4% (2 wt% B4C-reinforced composites) compared with TC11 alloy. However, the addition of 2 wt% Fe at the same B4C level (2 wt% B4C + 2 wt% Fe-reinforced composites) resulted in a significant increase in hardness by 37.5% and 15.2% in compressive strengths of TMC and can be attributed to the solid solution strengthening effect and higher dislocation density provided by the addition of Fe. In addition, the optimal overall properties can be achieved by strictly regulating the addition ratio of 2 wt% Fe and 1 wt% B4C, allowing for a compressive strength of 2301 MPa while still maintaining a compressive strain of 24.6%.

Metastable β type Ti-34Nb-4Zr-0.3O(mass fraction/%)alloy (TNZO) was prepared by vacuum arc melting, single-phase hot forging and cold rolling. The cold-rolled TNZO alloys were aged at low-temperature of 250 ℃ and 300 ℃ in order to reveal the effect of aging temperature and time on the precipitation behavior of ω phase and the mechanical properties of the alloys. The results show that ω phase precipitates in nanometer size as a result of low temperature aging which leads to the increase of strength and elastic modulus of the alloys. ω phase is easy to coarsen and agglomerate when the alloy is aged at 300 ℃, which results in the rapid drop of the elongation and embrittlement of the alloy. Short time aging at 250 ℃ could make the ω phase precipitated dispersedly with small volume fraction, enabling the alloy to have excellent comprehensive properties of high strength, low modulus, ultra-high elasticity and good plasticity and show a broad application prospect in the field of aerospace elastic titanium alloys and medical implant titanium alloys.

Methylammonium lead halide perovskites with highly efficient pure-color or white-light generation have gained increasing scientific interest and promote the development of a great commercial opportunity in displays, lighting, and other applications. However, the poor stabilities, lead toxicity, and unfriendly solvents and ligands in the growth process severely restrict their commercial application. Here, we proposed a green method for preparing uniform and stable polymer-encapsulated photoluminescence (PL) tunable CH3NH3PbBr3-xClx NC thin films at room temperature. Utilizing the swelling effect between alcohol compounds and organic polymers and the ionization of NaCl in methanol solution, the anion exchange process can be achieved rapidly within 7 min. Moreover, the PL wavelengths of the CH3NH3PbBr3-xClx NCs films were precisely tuned with steps as fine as 2 nm. Experimental results showed that NaCl dissolved in methanol solution can form Cl-(CH3OH)(n), which brings ionized Cl into the polymer-encapsulated CH3NH3PbBr3 NCs film for CH3NH3PbBr3-xClx NCs film growth. Based on the swelling and anion exchange dynamics, a modified NaCl-CH3OH-MABr solution system was developed to trigger CH3NH3PbBr3-xClx NCs film PL emission tuning from 528 to 463 nm with several-fold intensity enhancement. The realization of precisely controlled photoluminescence from the perovskite nanocrystal film would have wide applications in the optical and imaging fields.

Printable HTM-free (HTM = hole -transporting material) mesoporous carbon -based perovskite solar cells (C-PSCs) are one of the most promising technologies. In this study, a high -quality chlorinated mesoscopic TiO2 (m-TiO2) film was obtained by hydrochloric acid (HCl) wet chemical process and applied in C-PSCs based on TiO2/ZrO2/ (5-AVA)x(MA)1-xPbI3/C structures. Experimental results show that the PCE of chlorinated m-TiO2 C-PSCs greatly improved. Based on (5-AVA)x(MA)1-xPbI3, C-PSCs with TiO2 ETL treated with HCl aqueous solution achieved an average photovoltaic conversion efficiency of 9.36 %, which is an increase of 7.96 % in comparison with the efficiency of the device using unmodified TiO2 ETL, while the Voc and the Jsc were increased by 3.63 % and 2.63 %, respectively. In a 30 -day aging test, C-PSCs based on (5-AVA)x(MA)1-xPbI3 and TiO2-HCl 1 exhibited excellent stability under ambient air conditions.

Because of the strong light absorption and/or scattering, nano scaled gold has many favorable optic and electric properties. With the continuous miniaturization of nano photoelectronic devices and nano electromechanical systems, there is an urgent demand for controllable and tailored gold nanoparticles film with excellent performance. Here, a modified HAuCl4-NaOH-CTAB (cetyltrimethylammonium bromide) aqueous solution system was utilized to self-assembly synthesize gold nanofilm on glass substrates. The high concentration NaOH is not only reducing Au3+ to Au0, but facilitating interfacial assembly of gold nanostructure at liquid–solid interface via etching glass surface. Based on this growth kinetic, the gradient, well-designed and in-situ growing gold nanoparticles film can be achieved on any SiO2 contained substrates by controlling the growth time in the reaction system. Furthermore, the in-situ self-assembled gold nanoparticles film can be act as plasmon substrates for surface-enhanced Raman scattering (SERS) or plasmonic enhanced semiconductor lasing, even gold electrodes.

In this work, the La substitution of iron and replacing the oxygen with fluorine are both adopted to expectantly enhance the rate performance and structure stability of LiFePO4 during working. The characterizations of X-ray diffraction, scanning electron microscope, transmission electron microscope, charging-discharging tests, electrochemical impedance spectroscopy and safety tests are used to investigate the influences of La3+ and F- doping on the LiFePO4. The results indicate the cathodes after La3+ doping not only deliver the larger lattice parameters and unit cell volume to broaden the lithium ions migration pathway and accelerate the Li + diffusion speed, but also strengthen the whole bond energy of LiFePO4 owing to the high bond energy of La-O. In addition, the F replacement of O could increase the length of Li-O bonds and decrease the length of P-O bonds, further be helpful to enhance the Li + diffusion between LiFePO4 phase and FePO4 phase due to the weakening of Li-O bonds. Finally, the La3+ and F- co-doped cathode delivers the superior discharge capacity of 139.3 mAh g-1 at 5C high rate and 127.2 mAh g-1 at -20 degrees C, with the high discharging capacity of 160.1 mAh g-1 after 100 cycles at 45 degrees C.

PbX(OH) (X = Cl, Br, I) is considered one of the effective encapsulation matrixes to improve the stability and luminescence efficiency of perovskites. Several strategies have been explored to construct perovskite@PbBr(OH) composites with high photoluminescence quantum yield. However, there is limited research on their precise growth kinetics mechanism and morphology control. Herein, PbBr2 microwires (MWs) were applied to act as the lead source and serve as a skeleton frame for the growth of CH3NH3PbBr3 (MAPbBr(3)) MWs. The structure transition from MAPbBr(3) to MAPbBr(3)@PbBr(OH) MWs was triggered by the synergistic effect of H2O and CH3NH3OOCCH3 (methylamine acetate, MAAc). All components and synthesis processes used in this system are explicit, which allows a more in-depth exploration of the MAPbBr(3)@PbBr(OH) formation kinetics. The results indicate that the hydrolysis of MAAc provides OH- and partly replaces Br- ions in MAPbBr(3) to form the MAPbBr(x)Ac(3-x) intermediate, which induces the transformation of MAPbBr(3) into PbBr(OH) until the stable MAPbBr(3)@PbBr(OH) microwires are formed. Based on this growth kinetics process, utilizing H2O-MAAc and extra sodium halide (NaCl, NaI) mixture can synthesize MAPbBr(n)X(3-n)@PbX(OH) (X = Cl, I) microwires successfully. Our study can open a new avenue for developing high-efficiency and high-stability fluorescent hybrid perovskites for three primary color detectors, lasing cavities, and sensors.

AbstractIn geothermal energy development, high-temperature rock mass will go through the process of water cooling. It is of great significance to study the physical and mechanical characteristics and microstructure of high-temperature rock after water cooling for the long-term stability analysis of underground engineering. Based on this, the surface characteristics, mass, and volume variation of sandstone cooled by water at high temperatures (100, 200, 400, 600, 800, and 1000 °C) were investigated. Using the Rock Top multifield coupling tester, a series of axial compressions and longitudinal wave velocity tests of the sandstone after a high temperature-water cooling treatment are performed. The microstructure characteristic obtained by X-ray diffraction and scanning electron microscope was studied, and the effect of high temperature-water cooling behavior on the mechanical properties of sandstone was investigated. The results show that: (1) The mass loss rate, volume expansion rate and peak strain of sandstone increase with increasing temperature, while peak strength decreases gradually. When the temperature exceeds 400 °C, the physical and mechanical parameters of sandstone change markedly. (2) When the temperature is less than 400 °C, corresponds to the compressive and line-elastic phases, the stable crack propagation phase, the rapid crack propagation phase and the destructive phase during the failure process of sandstone, the wave velocity of sandstone are steadily increasing, oscillating, and sharply decreasing, respectively. While the temperature is below 1000 °C, the wave velocity of sandstone is oscillation increases, slows down and drops sharply, respectively. (3) When the temperature is below 400 °C, the mineral content of sandstone varies less. While the temperature exceeds 400 °C, there is an overall increasing trend in the sodium feldspar content of sandstone. (4) The increase in temperature promotes the development of pore fractures within the sandstone, especially at higher temperature states where microcracks expand along the intergranular to form microcrack networks, leading to an increase in the scale and number of defects such as fractures within the sandstone.

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Architecting tightly bonded interface microstructure is the principal guarantee for increased mechanical prop-erties of titanium matrix composites (TMCs). Adopting an effective technique to modulate interface structure is desirable to break through the trade-off of strength-ductility. Herein, a strategy is applied to establish inter-locking interface in multilayer graphene (MLG) reinforced Ti6Al4V (TC4) matrix TMCs by spark plasma sintering (SPS) with subsequent spark plasma forging (SPF). By this technique, 3D network-structured composites of 0.35 wt% MLG/TC4 with tailored network size are fabricated via varied TC4 particle sizes (2-15 mu m, 15-53 mu m, 63-97 mu m, 120-150 mu m), then their microstructure and mechanical properties are explored systematically. Results depict that enhanced interface bonding and oriented configuration of reinforcements are generated in inhomogeneous network architecture with diminished internal defects by minimizing agglomerations after deformation, simultaneously enhancing the strength and ductility. Among the different network sizes, SPFed composite with 15-53 mu m TC4 powder displays the better maintained tensile ductility (epsilon, 10.2%) with remarkably higher yield strength (YS, sigma 0.2) of 1089 MPa (27.52% higher than TC4), resulting in excellent strength-ductility synergy. Strengthening mechanisms and corresponding contributions are further discussed systematically. The work provides a valuable and facile pathway to prepare high-performance TMCs with outstanding interface microstructure.

In chemical synthesis of gold nanostructures, reducing agents are always needed in the preparation process. Meanwhile, NaOH acts as accelerator also playing an important role. Even though previous calculations have shown that NaOH and HAuCl4 with a certain chemical ratio can be used for the preparation of gold nano -materials, but there is no experimental confirmation. Here, we investigated and demonstrated the gold nano -structures growth process in HAuCl4-CTAB-NaOH system without any reductant in details. All results can be assigned that the reaction system can be carried out at room temperature with an ultralow growth rate (more than two weeks) and long-term stability. UV-vis, transmission electron microscopy (TEM) and PH monitoring were used characterized the as-prepared gold nanostructures which corresponding to (1 1 1) plane's gold nanoclusters and (200) plane's gold nanoparticles obtained. It is expected to be applied to the accurate prep-aration of gold nanostructures.

By implementing normalizing and simulatd post-weld heat treatment（SPWHT）tests on 80 mm thickness A537CL1 hot rolled steel plate for low temperature pressure vessel, the effects of microstructure evolution law on mechanical properties in the process of heat treatment are studied.The results show that the ferrite of hot rolled plate is refined after normalizing treatment, the strength at 1/4 thickness position is reduced while the toughness is greatly improved, the strength and toughness at 1/2 thickness position have no obvious changes while the plasticity is greatly improved.After SPWHT treatment, the proportion of ferrite increases, the spheroidization of cementite occurs and the cementite distributed at the grain boundaries coarsens, and the growth of microalloyed precipitates lead to the decrease of strength and low temperature impact toughness.The causes of low toughness at 1/2 thickness position in different states are further analyzed.

Strong interfacial bonding is the primarily crucial issue in titanium matrix composites (TMCs). In this study, three-dimensional (3D) network structured Ti6Al4V (TC4) matrix TMCs with 0.15 wt% few-layer graphene (FLG) were fabricated by high pressure spark plasma sintering (SPS, 200-300 MPa) at 850 ?, 900 ? and 950 ?, correspondingly producing three types of interface configuration with in-situ TiC to FLG ratio of 4:6, 7:3 and 9:1. Composites sintered under 900 ? displayed outstanding integrated properties, including high micro-hardness (345.2 HV), excellent ultimate tensile strength (UTS, 1041 MPa) with acceptable tensile ductility (epsilon, 9.3%) and wear resistance with the lower wear rate (omega, 5.3 x 10(-4) mm(3)/Nm). The synergistic effect of moderately generated TiC reinforcements on FLG (ratio of 7:3) in 3D network boundary under 900 & DEG;C leads to efficient load bearing capacity, acting as the dominant strengthening mechanism. Self-lubricating effect of FLG and debris strengthening of TiC and TiO2 are also responsible for improved wear resistance.