A polymer controlled nucleation route towards the generalized growth of organic-inorganic perovskite single crystals

Recently, there are significant progresses in the growth of organic-inorganic lead halide perovskite single crystals, however, due to their susceptible nucleation and growth mechanisms and solvent requirements, the efficient and generalized growth for these single crystals is still challenging. Here we report the work towards this target with a polymer-controlled nucleation process for the highly efficient growth of large-size high-quality simple ternary, mixed-cations and mixed-halide perovskite single crystals. Among them, the carrier lifetime of FAPbBr3 single crystals is largely improved to 10199 ns. Mixed MA/FAPbBr3 single crystals are synthesized. The crucial point in this process is suggested to be an appropriate coordinative interaction between polymer oxygen groups and Pb2+, greatly decreasing the nuclei concentrations by as much as 4 orders of magnitudes. This polymer-controlled route would help optimizing the solution-based OIHPs crystal growth and promoting applications of perovskite single crystals.

Heuristic Design of Advanced Martensitic Steels That Are Highly Resistant to Hydrogen Embrittlement by ε-Carbide

Many advanced steels are based on tempered martensitic microstructures. Their mechanical strength is characterized by fine sub-grain structures with a high density of free dislocations and metallic carbides and/or nitrides. However, the strength for practical use has been limited mostly to below 1400 MPa, owing to delayed fractures that are caused by hydrogen. A literature survey suggests that ε-carbide in the tempered martensite is effective for strengthening. A preliminary experimental survey of the hydrogen absorption and hydrogen embrittlement of a tempered martensitic steel with ε-carbide precipitates suggested that the proper use of carbides in steels can promote a high resistance to hydrogen embrittlement. Based on the surveys, martensitic steels that are highly resistant to hydrogen embrittlement and that have high strength and toughness are proposed. The heuristic design of the steels includes alloying elements necessary to stabilize the ε-carbide and procedures to introduce inoculants for the controlled nucleation of ε-carbide.