Nd2Fe14B nanoparticles are widely used because of their outstanding hard magnetic properties. In fact, Pr2Fe14B has higher magneto-crystalline anisotropy than Nd2Fe14B, which makes Pr-Fe-B a promising magnetic material. However, the chemical synthesis route to Pr2Fe14B nanoparticles is challenging because of the higher reduction potential of Pr3+, as well as the complex annealing conditions. In this work, Pr2Fe14B nanoparticles were successfully synthesized via an efficient and green mechanochemical method consisting of high energy ball milling, annealing, and a washing process. Microstructural investigations revealed that the oxide precursors were uniformly wrapped by CaO and CaH2, which formed an embedded structure after ball milling. Then, Pr2Fe14B powder was synthesized via a time-saving annealing process. The impact of the Pr2O3 content and the preparation conditions was investigated. The coercivity of the as-annealed powder with 100 wt% Pr2O3 excess is 18.9 kOe. After magnetic alignment, the coercivity, remanence, and maximum energy product were: 9.8 kOe, 78.4 emu g−1, and 9.8 MGOe, respectively. The present work provides a promising strategy for preparing anisotropic Pr-Fe-B permanent magnetic materials.
Lei Meng,Bin Yao,Yongfeng Li,Zhanhui Ding,Zhenyu Xiao,Kaisi Liu,Gang Wang
The back contact adhesion is the important factor of the microstructural performance which can determine the optoelectronic properties of the kesterite-based solar cells. Here, we present a rational and effective strategy to significantly enhance the back contact adhesion of Cu 2 (Zn,Cd)Sn(S,Se) 4 (CZCTSSe) absorber layers by insetting the appropriate thickness carbon-doping CZCTS thin films . We chose the oleylamine as the carbon-doping reagent which can generate a small amount of carbon in the annealing process . The suitable thickness carbon-doping CZCTS films can significantly change the crystal growth mechanism of CZCTSSe absorber layers, and eliminate the holes in the back contact. The efficiency of CZCTSSe solar cells fabricated by insetting the appropriate thickness carbon-doping CZCTS films is above 7%, and shows the excellent repeatability and long-term air stability compared with the control devices.
Transition metal sulfides have great potential as anode materials for sodium-ion batteries (SIBs) due to their high theoretical specific capacities. However, the inferior intrinsic conductivity and large volume variation during sodiation–desodiation processes seriously affect its high-rate and long-cycle performance, unbeneficial for the application as fast-charging and long-cycling SIBs anode. Herein, the three-dimensional porous Cu 1.81 S/nitrogen-doped carbon frameworks (Cu 1.81 S/NC) are synthesized by the simple and facile sol–gel and annealing processes, which can accommodate the volumetric expansion of Cu 1.81 S nanoparticles and accelerate the transmission of ions and electrons during Na + insertion/extraction processes, exhibiting the excellent rate capability (250.6 mAh·g −1 at 20.0 A·g −1 ) and outstanding cycling stability (70% capacity retention for 6000 cycles at 10.0 A·g −1 ) for SIBs. Moreover, the Na-ion full cells coupled with Na 3 V 2 (PO 4 ) 3 /C cathode also demonstrate the satisfactory reversible specific capacity of 330.5 mAh·g −1 at 5.0 A·g −1 and long-cycle performance with the 86.9% capacity retention at 2.0 A·g −1 after 750 cycles. This work proposes a promising way for the conversion-based metal sulfides for the applications as fast-charging sodium-ion battery anode.
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