Materials Letters最新文献

In this work, the novel CoCrNi composite with as high fraction as 5 wt% TiC reinforcements were additively manufactured (AMed) by laser powder bed fusion (LPBF) of blended powders of nano-C particles, spherical micro-Ti powders and spherical CoCrNi powders, instead of blended powders of nano-TiC and CoCrNi powders. This method resulted in fully melting of C and Ti elements during laser fusion and subsequent precipitation of nano-TiC during solidification. The agglomeration of nano-TiC in the matrix is reduced by this method, resulting in an 1800 MPa ultrahigh strength, simultaneously maintaining a considerable elongation of 12 %. Rise in the fractions of TiC from 0 to 5 wt% reduces intensity of the texture and grain size in the matrix and convert the strong 〈1 0 1〉 texture to relative weak 〈1 0 0〉 texture along building direction (BD).

Epoxy-polycarbonate sandwiched films with enhanced dielectric performance were prepared in this study. Unlike traditional tedious multiple scratch-coating approach, the sandwich dielectric films were prepared based on a convenient solution-immersion process. Polycarbonate solutions with different concentration were applied to adjust the film composition and compared with epoxy-polycarbonate blending film. We found that rather than deteriorating the breakdown strength as shown in the blending counterpart, sandwiched films prepared by solution immersion shows superior breakdown strength (709.6 MV/m), almost 40 % better than both epoxy and polycarbonate components. Moreover, tan δ of the films prepared from solution-immersion (<0.005) is apparently smaller than blending samples (∼0.008). Both factors lead to admirable ideal dielectric energy storage performance (8.44 J/cm³) of the film, better than many conventional polymers.

Stress-induced FCC-BCC phase transformation plays a crucial role in the mechanical behaviors of high-entropy alloys (HEAs). While there has been extensive research on this transformation during monotonic deformation, studies on fatigue behavior are extremely limited. Here, we use molecular dynamics simulations to investigate phase transformation and dislocation evolution in HEAs under strain-controlled symmetric tension–compression cycles. Our results show that cyclic deformation behavior is sensitive to strain amplitude, revealing three distinct cyclic responses. Notably, a progressive FCC-BCC phase transformation process occurs at a high strain amplitude of 4.8%. Grain boundaries and their triple junctions are identified as preferred sites for phase transformation under cyclic loading conditions. These findings provide valuable atomic-scale insights for understanding fatigue deformation in HEAs with transformation-induced plasticity.

Porous silicon nanoparticles (pSiNPs) have received considerable spotlight in drug delivery systems due to their biocompatibility, drug loading capacity, and easy surface modification. Despite these merits, the degradation rate control of pSiNPs in biological environments remains a challenge for sustained-release applications. In this study, we introduce a novel formulation of pSiNPs-based coated with carboxymethyl cellulose (pSiNPs-CMC) for the first time. The drug loading and release behavior of pSiNPs-CMC, featuring representative anticancer drugs such as doxorubicin, gemcitabine, paclitaxel, and SN-38, were extensively characterized. Notably, the CMC coating on pSiNPs resulted in an increase in loading efficiency of over 60% both for hydrophilic and hydrophobic drugs, while ensuring a controlled and tailored drug release profile. Our findings present the potential of the pSiNPs-CMC composite as a robust and versatile platform, overcoming conventional limitations in drug specificity and representing a significant advancement in sustained and personalized drug delivery systems.

Herein, a graphene oxide (GO)-hybridized Mg–Fe–layered double hydroxide (LDH) coating loaded with zinc ion (Zn²⁺) was grown vertically on Mg alloys via electrostatic assembly. These LDH nanosheets could effectively attract and anchor GO nanosheets, considerably improving the anticorrosion, cell adhesion, and cell proliferation properties of the Mg substrate. Meanwhile, Zn²⁺ was loaded onto the coating via the negatively charged GO surface to enhance their antibacterial activity against Escherichia coli and Staphylococcus aureus. Thus, the designed multilayer coating provides a new platform to address the current shortcomings, including rapid corrosion and insufficient antibacterial activities, using Mg-based alloys as bone implants.

Self-powered visible light photodetector based nanostructured CdSe/Si geometry was fabricated using pulsed laser deposition (PLD). Herein, a detailed microstructural investigation was demonstrated in conjunction with the overall device photoresponsive performance. Particularly, an average particle diameter of 66.62 $\mathrm{nm}$ along optical band gap of 2.25 $\mathrm{eV}$ were attained. This was, subsequently, perceived in the fabricated device spectral response performance during which photocurrent ($I_{\mathrm{ph}}$) of 47 µA was attained under incident light of 575 $\mathrm{nm}$ and 6 $\mathrm{mW}/{\mathrm{cm}}^2$, the nearest incident wavelength to the obtained optical band gap. At the reported incident light features, the proposed arrangement exhibited responsivity ($R_{\lambda }$) of 7.85 $\mathrm{mA}/W$ with light to dark current ratio ($I_{\mathrm{ph}}/I_D$) of 998 %, respectively. Herein, the incident power variation suggested a linear increment ($R^2\approx$ 0.94) in both $I_{\mathrm{ph}}$ and $I_{\mathrm{ph}}/I_D$ profiles, with values of 71 µA and 1501 %, respectively, at 575 $\mathrm{nm}$ and 26 $\mathrm{mW}/{\mathrm{cm}}^2$. The fabricated device exhibited a pronounced time-resolved feature with rise/fall periods of 0.31 and 0.34 sec., while the power dependance based time-resolved behavior indicated a linear correlation between the stated factors with $R^2$ value of 0.924, both of which were carried out at 0 bias voltage. The dual-singularity evidenced the self-powered feature of the proposed photodetector, where zero external potential is required.

The dual-transition metal Mo₂TiC₂ MXene shows promising applications in energy storage due to its unique physicochemical properties. However, existing methods for preparing Mo₂TiC₂ MXene often rely on the use of fluorine-containing chemical reagents, leading to environmental pollution and safety hazards. Here, we introduce a novel water-free solvothermal method for etching Mo₂TiAlC₂, successfully eliminating the aluminum atomic layer to obtain accordion-like Mo₂TiC₂ MXene. During the synthesis process, we found that the combined use of ammonium chloride and dimethyl sulfoxide in a water-free environment at 150°C can selectively etch aluminum, providing a new approach for the efficient synthesis of Mo₂TiC₂ MXene. Present research offers a feasible pathway for the environmentally friendly preparation of non-toxic MXene materials, which can further propel the applications and developments of MXene materials in the fields of energy storage and catalysis.

In this work, novel surface defected lead-free double perovskite oxide (Sr₂FeTeO₆) has been introduced in dye sensitized solar cells (DSSCs) for the first time. The Sr₂FeTeO₆ material prepared by solid state method treated at 1200 °C. The DSSC was performed with varying weight percentage (0.01 wt%, 0.03 wt%, 0.05 wt%) of Sr₂FeTeO₆ additives incorporated with titanium di-oxide (TiO₂) photoanode for light harvesting under AM 1.5 solar irradiation. The inorganic double perovskite oxide material as promising additive would be in the future developing 3rd generation solar cell technologies.

To encapsulate metal sulfides/selenides into carbon substrates is effective to enhance the cycling stability and rate capability of sodium-ion batteries (SIBs). In this paper, ZnSe nanoparticles rooted in N-doped carbon nanofibers (ZnSe@CNFs) were prepared by typical electrospinning technique coupled with carbonization and selenylation. As a result, ZnSe nanoparticles were wrapped by multichannel carbon fibers, which is conducive to the fast transport of sodium-ions and electrons and ensure the structural integrity. Benefiting from the special structure and the synergistic effect of two constituent, ZnSe@CNFs anode exhibits superior cycling stability of 2000 cycles at 1 A/g, with a capacity retention rate of 97.4%, equivalent to 0.0132‰ of attenuation per cycle. The carbon-encapsulation method involved in this paper has great application potential in the preparation of electrode materials.

This study proposes a through-process multi-scale modeling and simulation framework to predict the microstructural evolution during thermo-mechanical processing of a commercially pure titanium thick plate laser welding joint while accounting for process heterogeneities. The modeling strategy employs coupled physical-based macroscale and mesoscale finite element modeling to simulate the process and microstructural heterogeneities during welding and mechanical processes, as well as coupled cellular automata modeling to simulate the microstructural evolution during the subsequent annealing process. The EBSD data of the laser-welded joint served as input for the modeling framework. The experimental and simulation results for microstructure morphologies, grain size distributions, and transformation kinetics are consistent, demonstrating the reliability of our modeling technique.