Rapid synthesis of Bi and Sb sulfides using electric discharge assisted mechanical milling

Group V–VI binary sulfides are semiconductors, and find application in a number of commercial devices. Synthesis of these metal sulfides is problematic, and traditional synthesis techniques utilizing thermal and chemical means have disadvantages such as a long process time, contamination, and the use of toxic substances. In this work, the novel synthesis technique of electric discharge assisted mechanical milling (EDAMM) has been used to rapidly synthesize Bi₂S₃ and Sb₂S₃ powders from elemental S and Sb/Bi powders. This technique is shown to be both rapid and successful, and produces crystalline metal sulfide powders with a particle size of approximately 2 μm.

Mesityltellurenyl cations stabilized by triphenylpnictogens [MesTe(EPh₃)] + (E = P, As, Sb)

The homoleptic 1:1 Lewis pair (LP) complex [MesTe(TeMes₂)]O₃SCF₃ (1) featuring the cation [MesTe(TeMes₂)]+ (1a) was obtained by the reaction of Mes₂Te with HO₃SCF₃. The reaction of 1 with Ph₃E (E = P, As, Sb, Bi) proceeded with substitution of Mes₂Te and provided the heteroleptic 1:1 LP complexes [MesTe(EPh₃)]O₃SCF₃ (2, E = P; 3, E = As) and [MesTe(SbPh₃)][Ph₂Sb(O₃SCF₃)₂] (4) featuring the cations [MesTe(EPh₃)]+ (2a, E = P; 3a, E = As; 4a, E = Sb) and the anion [Ph₂Sb(O₃SCF₃)₂]− (4b). In the reaction with Ph₃Bi, the crude product contained the cation [MesTe(BiPh₃)]+ (5a) and the anion [Ph₂Bi(O₃SCF₃)₂]− (5b); however, the heteroleptic 1:1 LP complex [MesTe(BiPh₃)][Ph₂Bi(O₃SCF₃)₂] (5) could not be isolated because of its limited stability. Instead, fractional crystallization furnished a large amount of Ph₂BiO₃SCF₃ (6), which was also obtained by the reaction of Ph₃Bi with HO₃SCF₃. The formation of the anions 4b and 5b involves a phenyl group migration from Ph₃E (E = Sb, Bi) to the MesTe+ cation and afforded MesTePh as the byproduct, which was identified in the mother liquor. The heteroleptic 1:1 LP complexes 2–4 were also obtained by the one-pot reaction of Mes₂Te, Ph₃E (E = P, As, Sb) and HO₃SCF₃. Compounds 1–4 and 6 were investigated by single-crystal X-ray diffraction. The molecular structures of 1a–4a were used for density functional theory calculations at the B3PW91/TZ level of theory and studied using natural bond order (NBO) analyses as well as real-space bonding descriptors derived from an atoms-in-molecules (AIM) analysis of the theoretically obtained electron density. Additionally, the electron localizability indicator (ELI-D) and the delocalization index are derived from the corresponding pair density.

Fabrication of multifunctional graphene decorated with bromine and nano-Sb₂O₃ towards high-performance polymer nanocomposites

Despite great advances, it remains highly attractive but challenging to create high-performance polymeric materials combining excellent flame-retardancy and outstanding thermal, mechanical and electrical properties. We herein demonstrate a novel strategy for fabricating a multifunctional nano-additive (Br-Sb2O3@RGO) based on graphene decorated with bromine and nano-Sb2O3. Cone calorimetric tests show that incorporating 10 wt% Br-Sb2O3@RGO into thermoplastic polyurethane (TPU) strikingly prolongs the time to ignition and decreases the peak heat release rate by 72%. Besides, tensile strength and Young's modulus are enhanced by 37% and 820%, respectively. Meanwhile, the electric conductibility is increased by eleven orders of magnitude relative to the TPU matrix. This work provides a promising strategy for addressing the critical bottleneck with the existing flame retardants that only enhance flame retardancy at the expense of mechanical properties of polymeric materials. As-prepared high-performance TPU composites are expected to find many applications, especially in aerospace, tissue engineering, and cables and wires.