Ruixin Guo,Shu Guo,Mingjun Xia,Lijuan Liu,Minjuan Li,Sangen Zhao,Xiaoyang Wang
Ba1.09Pb0.91Be2(BO3)2F2 (BPBBF), a previously unreported lead-containing beryllium borate fluoride, has been successfully grown through a high-temperature flux method. Its structure is solved by single-crystal X-ray diffraction (SC-XRD), and it is optically characterized via infrared, Raman, UV–vis–IR transmission, and polarizing spectra as well. SC-XRD data suggests that it can be indexed by a trigonal unit cell (space group P3m1) with lattice parameters a = 4.7478(6) Å, c = 8.3856(12) Å, Z = 1, and V = 163.70(5) Å. This material could be considered as a derivative of the Sr2Be2B2O7 (SBBO) structural motif. It consists of 2D [Be3B3O6F3]∞ layers in the crystallographic ab plane, with divalent Ba2+ or Pb2+ cations serving as spacers among the adjacent layers. Ba and Pb were found to adopt a disordered arrangement in the trigonal prismatic coordination within the BPBBF structural lattice, which is evidenced by both structural refinements against SC-XRD data and energy dispersive spectroscopy. The UV absorption edge (279.1 nm) and birefringence (Δn = 0.054@ 546.1 nm) of BPBBF are confirmed by UV–vis–IR transmission and polarizing spectra, respectively. The discovery of this previous unreported SBBO-type material, BPBBF, along with other reported analogues such as BaMBe2(BO3)2F2 (M = Ca, Mg, and Cd), provide a prodigious example for tuning the bandgap, birefringence, and short UV absorption edge via simple chemical substitution.
Haolin Li,Lin Ma,Ping Wen,Yunyan Han,Rui Dong,Mingjin Fan
The wide industrial application of titanium alloys requires lubricating materials with superior performance. Although ionic liquids have been recognized as potential choices for excellent lubricants, research on their tribological properties as applied to titanium alloys is not mature and systematic. In this work, a series of halogen-free sulfonate IL lubricants with different anions and cations were designed, synthesized, and applied to the titanium alloy (Ti-6Al-4V) friction pairs. From the perspective of molecular structure, the influencing factors on their physicochemical properties (thermal stability, viscosity) and tribological performances (friction-reducing and anti-wear performances) were explored, including the influences derived from their active element, chain length, molecular rigidity and branched chain structure. The lubricating mechanism contributed by the IL molecules and the Ti surfaces during sliding were analyzed by means of SEM, XPS, ECR and QCM. The results showed that physical adsorption and tribo-chemical reactions were involved during the sliding process. And the lubricating performances of the synthesized ILs may largely depend on their ability to form physical/chemical adsorption films on the titanium interfaces. The rigid benzene ring structure and flexible alkyl chain are conducive to strengthening the stability and efficiency of the formed interfacial tribo-film.
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