SnO 2 -doped CaSiO 3 ceramics were successfully synthesized by a solid-state method. Effects of different SnO 2 additions on the sintering behavior, microstructure and dielectric properties of Ca(Sn 1− x Si x )O 3 ( x =0.5–1.0) ceramics have been investigated. SnO 2 improved the densification process and expanded the sintering temperature range effectively. Moreover, Sn 4+ substituting for Si 4+ sites leads to the emergence of Ca 3 SnSi 2 O 9 phase, which has a positive effect on the dielectric properties of CaO–SiO 2 –SnO 2 materials, especially the Qf value. The Ca(Sn 0.1 Si 0.9 )O 3 ceramics sintered at 1375 °C possessed good microwave dielectric properties: ε r =7.92, Qf =58,000 GHz and τ f =−42 ppm/°C. The Ca(Sn 0.4 Si 0.6 )O 3 ceramics sintered at 1450 °C also exhibited good microwave dielectric properties of ε r =9.27, Qf =63,000 GHz, and τ f =−52 ppm/°C. Thus, they are promising candidate materials for millimeter-wave devices.
Bang Li,Guangfu Li,Qiqi Wan,Lei Yuan,Yingying Liu,Longxu Li,Xiaodong Zhuang,Junliang Zhang,Changchun Ke
Proton exchange membrane water electrolysis (PEMWE) is a promising technology for green hydrogen production. However, its large-scale commercial application is limited by its high precious metal loading, because low catalyst loading leads to reduced electron transport channels and decreased water transportation, etc. Herein, we study the electrode level strategy for reducing Ir loading by the optimization of the micro-structure of the anode catalyst layer via SnO2 doping. The pore structure and electron conductive network of the anode catalyst layer can be simultaneously improved by SnO2 doping, under appropriate conditions. Therefore, mass transfer polarization and ohmic polarization of the single cell are reduced. Moreover, the enhanced pore structure and improved electron conduction network collectively contribute to a decreased occurrence of charge transfer polarization. By this strategy, the performance of the single cell with the Ir loading of 1.5 mg cm−2 approaches the single cell with the higher Ir loading of 2.0 mg cm−2, which means that SnO2 doping saves about 25% loading of Ir. This paper provides a perspective at the electrode level to reduce the precious metal loading of the anode in PEMWE.
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