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The local electron density of an atom is one key factor that determines its chemical properties. Regulating electron density can promote the atom's reactivity and so reduce the reaction activation energy, which is highly desired in many chemical applications. Herein, we report an intra‐crystalline electron lever strategy, which can regulate the electron density of reaction centre atoms via manipulating ambient lattice states, for Fenton activity improvement. Typically, with the assistance of ultrasound, the Mn4+−O−Fe3+ bond in BiFe0.97Mn0.03O3 perovskite nanocrystals can drive valence electrons and free electrons to accumulate on Fe atoms by a polarization electric field originated from the designed lattice strain. The increase of electron density significantly improves the catalytic activity of Fe, decreasing the activation energy of BiFe0.97Mn0.03O3‐mediated Fenton reaction by 52.55 %, and increasing the.OH yield by 9.21‐fold. This study provides a new way to understand the sono‐Fenton chemistry, and the increased.OH production enables a highly effective chemodynamic therapy. [ABSTRACT FROM AUTHOR]

Non-reciprocal devices such as isolators and circulators, based mainly on ferromagnetic materials, require extremely low dielectric loss in order for strict power-link budgets to be met for millimetre (mm)-wave and terahertz (THz) systems. The dielectric loss of commercial SrFe12O19 hexaferrite was significantly reduced to below 0.002 in the 75–170 GHz band by thermal annealing. While the overall concentration of Fe2+ and oxygen vacancy defects is relatively low in the solid, their concentration at the surface is significantly higher, allowing for a surface sensitive technique such as XPS to monitor the Fe3+/Fe2+ redox reaction. Oxidation of Fe2+ and a decrease in oxygen vacancies are found at the surface on annealing, which are reflected in the bulk sample by a small change in the unit cell volume. The significant decrease in the dielectric loss property can be attributed to the decreased concentration of charged defects such as Fe2+ and oxygen vacancies through the annealing process, which demonstrated that thermal annealing could be effective in improving the dielectric performance of ferromagnetic materials for various applications. [ABSTRACT FROM AUTHOR]