Continuously Doping BiM₂Sr₂CaCu₂O_8+δ into Electron-Doped Superconductor by CaH₂ Annealing Method

Abstract

As a typical hole-doped cuprate superconductor, Bi2Sr2CaCu2O8+δ (Bi2212) carrier doping is mostly determined by its oxygen content. Traditional doping methods can regulate its doping level within the range of hole doping. Here we report the first application of CaH2 annealing method in regulating the doping level of Bi2212. By continuously controlling the anneal time, a series of differently doped samples can be obtained. The combined experimental results of x-ray diffraction, scanning transmission electron microscopy, resistance and Hall measurements demonstrate that the CaH2 induced topochemical reaction can effectively change the oxygen content of Bi2212 within a very wide range, even switching from hole doping to electron doping. We also found evidence of a low-Tc superconducting phase in the electron doping side.

Defect Engineering in Bi‐Based Photo/Electrocatalysts for Nitrogen Reduction to Ammonia

“…The first method involves the direct formation of a specific defect during the material preparation process, referred to as the one-step or in-situ synthesis approach. The second strategy is the post-treatment method, which the catalyst precursor is initially prepared and subsequently introduces regulable defects through a more precise process control strategy mainly including: reducing atmosphere treatment, [86,87] high temperature annealing treatment, [88][89][90] NaBH 4 reduction, [91,92] atomic substitution method, [93,94] plasma assisted method, [95] electrochemical reduction method, [39,53,96] in-situ photoinduction method [97] etc. These methods facilitate the intentional control of the type and concentration of defects in the electrocatalyst, thereby adjusting its electronic structure and introducing the surface active site of the NRR, which is summarized in detail below.…”