Through disorder - Controlled Transformation of Synthesized Multi-Principal-Element Intermetallic Compound Nanoparticles

https://doi.org/10.1126/sciadv.abm4322

Professor Liangbing Hu’s research group at the University of Maryland in the United States published in “ Science Advances 》 published a paper titled “ Multi-principal elemental intermetallic nanoparticles synthesized via a disorder-to-order transition “paper. The core of this study is to propose a disordered - An ordered-phase transformation strategy was employed to successfully synthesize multi-principal-element intermetallic compounds ( MPEI ) Nanoparticles have overcome the limitations of conventional synthesis methods, opening up new avenues for the research and application of related materials.

Research Background

Nanometer-scale intermetallic compounds, owing to their enormous active surface area and unique surface properties, exhibit remarkable potential in catalysis, magnetism, superconductivity, and other fields. of Application potential. To date, particle growth has been observed in multiphase alloys. / Regarding issues of phase aggregation and phase separation, the preparation of intermetallic nanoparticles remains confined to binary or ternary compositional systems. The synthesis of multi-component intermetallic compounds ( MPEI ; containing three or more elements) nanoparticle synthesis requires precise control of reaction conditions, whereas conventional synthesis methods, due to heating / The cooling rate is slow, Easily leads to particle growth and agglomeration, as well as elemental phase separation. The resulting polymetallic nanoparticles remain disordered solid-solution alloys. [i.e., high-entropy alloys (HEAs)], rather than ordered MPEI nanoparticles 。

Research Methods

This study employs a unique multi-element disorder. - Orderly ( HEA To MPEI ) Phase-change strategy (Figure 1A ), successfully synthesized compounds containing up to 8 Nanoscale metals of different elements - Organic hybrid materials ( MPEIs , size 4-5 nanometers), with no evidence of particle growth or phase separation.

1. Step 1: Preparation of disordered solid-solution high-entropy alloys ( HEA) Nanoparticles ， First, Loading metal salt precursors onto a carbon substrate, Through Approximately 1100K rapid Joule heating (continuous 55 milliseconds), yielding a disordered solid solution HEA Nanoparticles as the starting material.
2. Step 2: Disorder - Order-Disorder Phase Transition and Structural Locking ， Precise temperature control via Joule heating (approximately At 1100 K, HEA nanoparticles are heated for 5 minutes to promote atomic rearrangement and the formation of a thermodynamically stable, ordered intermetallic compound structure; they are then rapidly cooled at a rate of approximately 10⁴ K/s to lock in the ordered structure, ultimately yielding MPEI nanoparticles.

Research Results

1. Pioneering Using a “disorder–order phase transition” Joule-heating strategy, we have successfully synthesized MPEI nanoparticles with sizes of 4–5 nm and compositions containing up to eight elements, while enabling precise control over elemental ratios and crystal structures (such as the L1₀ and L1₂ phases). (Image 2 ) 。

2. A significant size effect exists: only Ultrafine particles smaller than 5 nm can undergo a fully disordered–ordered phase transition, whereas particles ≥60 nm are prone to phase separation or remain disordered. (Image 3 ) 。

3. MPEI exhibits a dual sublattice ordered structure with 100% long-range order and remains stable after heating at 1100 K for 60 minutes, demonstrating superior thermodynamic stability compared with binary intermetallic compounds and disordered high-entropy alloys. (Image 4 ) 。

4. Excellent catalytic activity and durability ： Eight yuan MPEI nanoparticles serve as electrocatalysts for ethanol oxidation, exhibiting eight times the activity of binary PtFe and twelve times that of commercial Pt/C, while also demonstrating outstanding durability. This is attributed to its multi-element composition, ordered crystal structure, and the synergistic effects arising from its nanoscale dimensions.

Methodological Advantages: The Core Value of the Joule Heating Strategy

Rapid heating via Joule heating compared with conventional annealing / Rapid cooling (~10⁴ K/s) combined with precise temperature control effectively prevents particle growth and agglomeration as well as elemental phase separation; by using a pre-mixed, disordered high-entropy alloy (HEA) as the precursor, the challenge of thermodynamic immiscibility among multiple elements is overcome, thereby providing an efficient and versatile route for the synthesis of MPEI. This work has opened up potential application areas for intermetallic nanomaterials, which hold great promise in catalysis, magnetism, superconductivity, and other fields.

Tianjin Zhonghuan Joule Heat Rapid-Firing Furnace Series