Eutectic melt crystallization of L10-FePt

Solid-State Reaction Synthesis of Nanoscale Materials: Strategies and Applications

Nanomaterials (NMs) with unique structures and compositions can give rise to exotic physicochemical properties and applications. Despite the advancement in solution-based methods, scalable access to a wide range of crystal phases and intricate compositions is still challenging. Solid-state reaction (SSR) syntheses have high potential owing to their flexibility toward multielemental phases under feasibly high temperatures and solvent-free conditions as well as their scalability and simplicity. Controlling the nanoscale features through SSRs demands a strategic nanospace-confinement approach due to the risk of heat-induced reshaping and sintering. Here, we describe advanced SSR strategies for NM synthesis, focusing on mechanistic insights, novel nanoscale phenomena, and underlying principles using a series of examples under different categories. After introducing the history of classical SSRs, key theories, and definitions central to the topic, we categorize various modern SSR strategies based on the surrounding solid-state media used for nanostructure growth, conversion, and migration under nanospace or dimensional confinement. This comprehensive review will advance the quest for new materials design, synthesis, and applications.

Rare-earth-free magnetically hard ferrous materials

Permanent magnets, especially rare-earth based magnets, are widely used in energy-critical technologies in many modern applications, involving energy conversion and information technologies. However, the environmental impact and strategic supplies of rare-earth elements hamper the long-term development of permanent magnets. Hence, there is a surge of interest to expand the search for rare-earth-free magnets with a large energy product (BH)_max. Among these rare-earth-free magnets, iron-based permanent magnets emerge as some of the most promising candidates due to their abundance and magnetic performance. In this review, we present a summary of iron-based permanent magnets from materials synthesis to their magnetic properties.

Eutectic crystallized FePd nanoparticles for liquid metal magnet

Magnetically hard nanoparticles have been widely explored in colloidal solution synthesis, while a high temperature-induced phase transformation is indispensable to achieve its high magnetocrystalline anisotropy. However, a long-standing challenge of magnetic nanoparticles is the inaccessibility of size-controlled growth without sintering-induced agglomeration. Here, we report a universal one-pot eutectic reaction scheme of magnetically hard FePd nanoparticles, in which the crystallization conditions are critical for its magnetic performance. We demonstrate that the stoichiometry between transition metal and eutectic salt and sintering temperature can play an important role in the magnetic coercivity of FePd nanoparticles. In addition, gallium liquid metal is employed as the conductivity filler for the formation of a magnetorheological fluid after mixing with metallic FePd nanoparticles. The liquid composite shows a high metallic and thermal conductivity as an unconventional cooling metallic ferrofluid conductor, and we further demonstrate its potential application in sensors, conductors and thermal interfaces.