Title: Discovery of Irregular Crystal Structures Challenges Previous Beliefs, Opens New Possibilities in Materials Science
Subtitle: Random Stacking of Hexagonal Layers Offers Potential Benefits in Silicon Carbide and Other Polytypic Materials
Date: April 15, 2023
A groundbreaking study led by researchers from Rensselaer Polytechnic Institute has shattered conventional beliefs about the arrangement of crystal structures, uncovering irregularly arranged patterns that could revolutionize the field of materials science. The findings, which challenge the established definition of crystals, hold significant implications for industries relying on materials such as semiconductors, solar panels, and high-voltage electronics.
Traditionally, crystals have been defined by their regular arrangement of components, whether they be atoms, molecules, or nanoparticles. However, the study led by associate professor Sangwoo Lee reveals that crystal structures can exhibit irregular arrangements, contradicting the widely accepted definition.
The researchers focused on the random stacking of two-dimensional hexagonal layers (RHCP), an unconventional structure that was previously considered a transitional and energetically unfavorable state. The RHCP structure, first observed in cobalt metal in 1942, has since been observed in numerous materials and naturally occurring crystal systems.
To unravel the complexities of RHCP, Lee’s team collected X-ray scattering data from soft model nanoparticles made of polymers. Analyzing the complex data with the help of the supercomputer system, Artificial Intelligence Multiprocessing Optimized System (AiMOS), they deduced that the RHCP structure is likely stable.
“The discovery challenges the classical definition of crystals,” explained Lee. “This finding demonstrates that RHCP has been widely observed in many materials and crystal systems.”
The study sheds light on polytypism, a phenomenon that allows for the formation of RHCP and other close-packed structures. Silicon carbide, a representative polytypic material widely used in high-voltage electronics and body armor, could undergo continuous structural transitions, including non-classical random arrangements, with potential applications and new properties.
“This paper provides compelling evidence for a continuous transition between face-centered cubic (FCC) and hexagonal close-packed (HCP) lattices, implying a stable random hexagonal close-packed phase,” commented Kevin Dorfman of the University of Minnesota-Twin Cities, who was not involved in the research. “This breakthrough in materials science has profound implications.”
Dean Shekhar Garde of Rensselaer’s School of Engineering praised the discovery, highlighting the power of advanced computation in decoding molecular-level structures in soft materials. The study led by Lee and Underhill also promises to open up new opportunities for technological applications using these novel materials.
The research, titled “Continuous transition of colloidal crystals through stable random orders,” was published in the journal Soft Matter. The team of researchers also included Juhong Ahn and Mikhail Zhernenkov from Rensselaer, Liwen Chen from the University of Shanghai for Science and Technology, and Guillaume Freychet from Brookhaven National Laboratory.
As scientists continue to explore the possibilities of irregularly arranged crystal structures, the future of materials science appears poised for innovative breakthroughs and transformative applications in various industries.