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Abstract We report a general chemical approach to synthesize strongly ferromagnetic rare‐earth metal (REM) based SmCo and SmFeN nanoparticles (NPs) with ultra‐large coercivity. The synthesis started with the preparation of hexagonal CoO+Sm ₂ O ₃ (denoted as SmCo‐O) multipods via decomposition of Sm(acac) ₃ and Co(acac) ₃ in oleylamine. These multipods were further reduced with Ca at 850 °C to form SmCo ₅ NPs with sizes tunable from 50 to 200 nm. The 200 nm SmCo ₅ NPs were dispersed in ethanol, and magnetically aligned in polyethylene glycol (PEG) matrix, yielding a PEG‐SmCo ₅ NP composite with the room temperature coercivity ( Hmore » _c ) of 49.2 kOe, the largest H _c among all ferromagnetic NPs ever reported, and saturated magnetic moment ( M _s ) of 88.7 emu g ⁻¹ , the highest value reported for SmCo ₅ NPs. The method was extended to synthesize other ferromagnetic NPs of Sm ₂ Co ₁₇ , and, for the first time, of Sm ₂ Fe ₁₇ N ₃ NPs with H _c over 15 kOe and M _s reaching 127.9 emu g ⁻¹ . These REM based NPs are important magnetic building blocks for fabrication of high‐performance permanent magnets, flexible magnets, and printable magnetic inks for energy and sensing applications.« less

We report here a general chemical approach to synthesize strongly ferromagnetic rare-earth metal (REM) based SmCo and SmFeN nanoparticles (NPs) with ultra-large coercivity. The synthesis started with the preparation of hexagonal CoO+Sm₂O₃ (denoted as SmCo-O) multipods via decomposition of Sm(acac)₃ and Co(acac)₃ in oleylamine. These multipods were further reduced with Ca at 850 °C to form SmCo₅ NPs with sizes tunable from 50 to 200 nm. The 200 nm SmCo₅ NPs were dispersed in ethanol, and magnetically aligned in polyethylene glycol (PEG) matrix, yielding a PEG-SmCo₅ NP composite with the room temperature coercivity (H_c) of 49.2 kOe, the largest H_cmore » among all ferromagnetic NPs ever reported, and saturated magnetic moment (M_s) of 88.7 emu g^-1, the highest value reported for SmCo₅ NPs. The method was extended to synthesize other ferromagnetic NPs of Sm₂Co₁₇, and, for the first time, of Sm₂Fe₁₇N₃ NPs with H_c over 15 kOe and M_s reaching 127.9 emu g^-1. These REM based NPs are important magnetic building blocks for fabrication of high-performance permanent magnets, flexible magnets, and printable magnetic inks for energy and sensing applications.« less

Presented here is a facile approach to bimetallic phosphides, Co-Fe-P, via high-temperature (300°C) reaction between Co-Fe-O nanoparticles and trioctylphosphine. The growth of Co-Fe-P from the Co-Fe-O is anisotropic. As a result, Co-Fe-P nanorods (from the polyhedral Co-Fe-O nanoparticles) and sea-urchin-like Co-Fe-P (from the cubic Co-Fe-O nanoparticles) are synthesized with both nanorod and the sea-urchin-arm dimensions controlled by Co/Fe ratios. The Co-Fe-P structure, especially the sea-urchin-like (Co_0.54Fe_0.46)₂P, shows enhanced catalysis for oxygen evolution reaction in KOH with its catalytic efficiency surpassing Ir catalyst. Our synthesis is simple and may be readily extended to the preparation of other multimetallic phosphides for importantmore » catalysis and energy storage applications.« less