RESUMEN
In this work, various Cu, Ni, Ag-microalloyed Sn-5Sb/Cu joints, ordinary Sn-5Sb/Cu joints, and low-melting-point Sn-3Ag-0.5Cu (SAC305)/Cu (used for comparison) were prepared, focusing on the influence of Cu, Ni, and Ag on the microstructure evolution, interfacial IMC growth, and microhardness of Sn-5Sb/Cu joint under long-time isothermal aging process. Results showed that the microstructure of microalloyed joints consisted of ß-Sn matrix, SbSn, and (Cu, Ni)6Sn5 and Ag3Sn compounds. (Cu, Ni)6Sn5 compounds generated a coarsening effect in the aging microalloyed joints, yet its coarsening speed is significantly lower than the ordinary Sn-5Sb/Cu. Meanwhile, the total IMC layer thickness increased with the rising aging time. A single fine dendritic (Cu, Ni)6Sn5 IMC at the interface of microalloyed joint was observed and evolved into a larger scallop or layer-like duplex IMCs ((Cu, Ni)6Sn5 + Cu3Sn) after the aging. Considering the combined effect of Cu, Ni, and Ag, the microalloyed joints exhibited the improved microstructure relative to ordinary counterparts and low-melting-point SAC305 materials, significantly inhibiting the interfacial IMC growth, especially Cu3Sn. The Cu3Sn IMC thickness and diffusion coefficient in the Sn-5Sb-0.5Cu-0.1Ni-0.5Ag/Cu joint were 0.71-2.81 µm and 0.96 × 10-6 µm·s-2, respectively. Besides, the precipitation strengthening mechanism triggered by the microalloyed elements was extremely obvious and the soldering and aging joints revealed superior microhardness values of 20-35 HV. This could effectively improve the application range of Sn-5Sb-based materials in higher-temperature package conditions such as third-generation semiconductors.
RESUMEN
Nanostructured transition metal sulfides are promising anode materials for lithium-ion batteries. Nevertheless, it is still a great challenge to prepare capacity-improved electrodes without reducing their rate capability and cycle stability. In this paper, we present a C/Co9S8@SnS2 composite material by loading SnS2 nanocrystals onto MOF-derived C/Co9S8 nanostructures. The C/Co9S8@SnS2 composite has multiple active sites to store lithium ions. The specific capacity reaches 3.1 mAh cm-2 when the current density is 0.224 mA cm-2. The asynchronous electrochemical reaction between Co9S8 and SnS2 offsets the volume expansion of the anode material. Meanwhile, the compact adhesion of carbon layers on the interfaces suppresses the destruction of the anode during the charging-discharging processes. Consequently, the synthesized electrode presents favorable capacity with high current density or under long-term cycling conditions. The prepared battery has a reversible specific capacity of 0.452 mAh cm-2 and a coulomb efficiency of 99.7% after 500 cycles with a high current density of 2.24 mA cm-2. The research results obtained in this work provides a feasible strategy to improve the performance of electrodes systematically.
RESUMEN
La(OH)3 nanorods immobilized in polyacrylonitrile (PAN) nanofibers (PLNFs) were fabricated for the first time by electrospinning and a subsequent in situ surfactant-free precipitation method and then applied as a highly efficient phosphate scavenger to realize nutrient-starvation antibacteria for drinking water security. The immobilization by PAN nanofibers effectively facilitated the in situ formation of the aeolotropic and well-dispersed La(OH)3 nanostructures and, thus, rendered higher phosphate removal efficiency due to more exposed active sites for binding phosphate. The maximum phosphate capture capacity of La(OH)3 nanorods in PAN nanofibers was around 8 times that of the La(OH)3 nanocrystal fabricated by precipitation without PAN protection. Moreover, remarkably fast adsorption kinetics and high removal rate were observed toward low concentration phosphate due to the high activity of our materials, which can result in a stringent phosphate-deficient condition to kill microorganisms in water effectively. The present material is also capable of preventing sanitized water from recontamination by bacteria and keeping water biologically stable for drinking. Impressively, stabilized by PAN nanofibers, the La(OH)3 nanorods can be easily separated out after reactions and avoid leaking into water. The present development has great potential as a promising antimicrobial solution for practical drinking water security and treatment with a negligible environmental footprint.
