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Sn-10Bi low-bismuth-content solder alloy provides a potential alternative to the currently used Sn-Ag-Cu series due to its lower cost, excellent ductility, and strengthening resulting from the Bi solid solution and precipitation. This study primarily investigates the interfacial evolution and shear strength characteristics of Sn-10Bi joints on a Ni/Au surface finish during the as-soldered and subsequent isothermal aging processes. To improve the joint performance, a 0.2 or 0.5 wt.% dopant of Zn was incorporated into Sn-10Bi solder. The findings demonstrated that a 0.2 or 0.5 wt.% Zn dopant altered the composition of the intermetallic compound (IMC) formed at the interface between the solder and Ni/Au surface finish from Ni3Sn4 to Ni3(Sn, Zn)4. The occurrence of this transformation is attributed to the diffusion of Zn atoms into the Ni3Sn4 lattice, resulting in the substitution of a portion of the Sn atoms by Zn atoms, thereby forming the Ni3(Sn, Zn)4 IMC during the soldering process, which was also verified by calculations based on first principles. Furthermore, a 0.2 or 0.5 wt.% Zn dopant in Sn-10Bi significantly inhibited the Ni3(Sn, Zn)4 growth after both the soldering and thermal aging processes. Zn addition can enhance the shear strength of solder joints irrespective of the as-soldered or aging condition. The fracture mode was determined by the aging durations—with the brittle mode occurring for as-soldered joints, the ductile mode occurring for aged joints after 10 days, and again the brittle mode for joints after 40 days of aging. [ABSTRACT FROM AUTHOR]

Ultrawide bandgap semiconductor, e.g., diamond, is considered as the next generation of semiconductor. Here, a new orthorhombic carbon allotrope (P212121-C16) with ultrawide bandgap and ultra-large hardness is identified. The stability of the newly designed carbon is confirmed by the energy, phonon spectrum, ab-initio molecular dynamics and elastic constants. The hardness ranges from 88 GPa to 93 GPa according to different models, which is comparable to diamond. The indirect bandgap reaches 6.23 eV, which is obviously larger than that of diamond, and makes it a promising ultra-wide bandgap semiconductor. Importantly, the experimental possibility is confirmed by comparing the simulated X-ray diffraction with experimental results, and two hypothetical transformation paths to synthesize it from graphite are proposed. [ABSTRACT FROM AUTHOR]

Three models having more consistent structural resemblance to the quinone form (TPQ) of a protein found in mammalian copper amine oxidase active sites are synthesized. These models differ in the nature of alkyl substituent. These quinone forms deaminate benzylamine in aqueous CH3CN, both catalytically and stoichiometrically. The pH-dependent benzenetriol to hydroxyquinone autooxidation and amine reaction with benzenetriol forms are examined to analyze aerobic autorecycling deamination.

The oxidation of aliphatic amines by (batho)2Cu(II) involves an initial outer-sphere one-electron transfer, followed by proton transfer to the solvent,then by a second one-electron oxidation to imine or iminium. When the resultingsecondary amine is oxidizable, a two-electron oxidation follows. An inner-sphere coordination of the amines, on the other hand, displaces the batholigand which limits the oxidation potential of Cu(II) and inhibits the redox reaction. Using excess Cu(II) oxidant induces regioeselectivity and chemoselectivity in the oxidation of amines to iminium.

The Ti(C, N) – Al 2 O 3 cermet to 40Cr steel joint was conducted by liquid phase diffusion bonding under the auxiliary pulse current and using 73Cu–27Ti amorphous foil/Cu foil/72Ag–28Cu foil sandwich foils as the interlayer. The effect of holding time and duty ratio of the pulse current on interfacial structure at the Ti(C, N) – Al 2 O 3 cermet side and joint strength were studied. The results showed that the longer bonding time can improve the melting of Cu–Ti foil and the dissolution of Cu interlayer to obtain a higher joint strength. The interfacial structure was composed of the TiCu compounds and Cu solid solution at the cermet side, and TiCu 4 compounds and Cu solid solution at the Cu interlayer side. The auxiliary pulse current was beneficial to reach a higher joint strength in a shorter holding time. A higher duty ratio would accelerate the dissolution and reaction of cermet to the interlayer, but continuous increase on the duty ratio would result in the over dissolution of cermet into the interface to produce the Ti(C, N) and Al 2 O 3 ceramic particles and the decrease on the joint strength. [ABSTRACT FROM AUTHOR]