Crystals, often perceived as simple structures, hold within them a complex narrative of growth and formation. Traditionally, scientists believed that crystals developed one building block at a time, following a straightforward path. However, recent research conducted by a team at New York University has unveiled a more intricate story. Their groundbreaking study reveals a two-step crystallization process, challenging long-held theories and introducing a novel crystal structure named Zangenite, unlike anything previously documented.
The announcement comes as researchers delve deeper into the microscopic world of colloids—tiny charged particles that mimic atomic behavior. This discovery not only reshapes our understanding of crystallization but also opens new avenues in material science, potentially impacting future technologies and filtration methods.
Seeing Crystals Come to Life
Crystals are typically composed of atoms that are too small and fast-moving to be observed directly under a microscope. To circumvent this limitation, researchers employ colloids, which are larger and slower-moving particles. This approach allows scientists to monitor the entire crystal growth process in real-time.
“The advantage of studying colloidal particles is that we can observe crystallization processes at a single-particle level,” explained Stefano Sacanna, a chemistry professor at NYU. “With colloids, we can watch crystals form with our microscope.”
This method provided the researchers with an unprecedented view of crystal formation, allowing them to observe how disordered particles gradually organize into structured forms. The team conducted extensive laboratory experiments and thousands of computer simulations to decipher the patterns they observed.
Growth Happens in Two Main Stages
One of the pivotal discoveries of this study is the realization that crystals do not merely grow particle by particle. Instead, they form through a two-step process. Initially, a cloud of disorganized blobs, known as a metastable phase, condenses from a gas-like suspension. These blobs consist of charged particles that have yet to align into a regular pattern.
Over time, these blobs evolve into small crystals with ordered structures. Subsequently, these small crystals expand into larger, smooth-faced formations through three primary actions: individual particles join in, blobs are absorbed, and smaller crystals attach in the same direction and adhere.
This behavior, meticulously tracked at the particle level for the first time, demonstrates that crystallization can follow multiple pathways. The strength of particle interactions and their size determine the resulting types and shapes of crystals. The team also discovered that by altering salt concentrations using a technique called continuous dialysis, they could manipulate the growth process, enabling the creation and study of various crystal structures within a single experiment.
A Strange and Hollow Surprise
During the experiments, PhD student Shihao Zang observed an unusual rod-shaped crystal. Unlike any other, this crystal featured hollow channels running through its tips. Despite comparing this structure with over a thousand known crystals, Zang found no match.
“We study colloidal crystals to mimic the real world of atomic crystals,” Zang stated, “but we never imagined that we would discover a crystal that we cannot find in the real world.”
To solve the mystery, the team consulted Glen Hocky, an expert in computer modeling. His simulations confirmed the existence of this peculiar crystal, validating that it was not a laboratory anomaly. “This was puzzling because usually crystals are dense, but this one had empty channels that ran the length of the crystal,” Hocky noted.
The team christened this new structure L3S4, based on its particle composition, but affectionately referred to it as “Zangenite” in honor of Zang. “Through this synergy of experiments and simulation, we realized that this crystal structure had never been observed before,” Sacanna added.
Hollow Crystals, Bright Possibilities
The hollow nature of Zangenite sets it apart. While most crystals are densely packed, Zangenite’s inner channels make it lighter and less dense. These features could have significant applications.
“The channels inside Zangenite are analogous to features in other materials that are useful for filtering or enclosing things inside them,” Hocky explained. Such structures could trap particles or allow fluids to flow through, much like filters or sponges. They might eventually aid in designing new tools for water purification, gas storage, or drug delivery.
“Before, we thought it would be rare to observe a new crystal structure,” Sacanna remarked. “But we may be able to discover additional new structures that haven’t yet been characterized.” Their ability to control particle interaction strength also enabled the growth of unusual composite crystals on surfaces—a process known as heteroepitaxy. This method facilitated the creation of new material combinations with potential technological applications.
The diverse shapes, sizes, and structures discovered in the lab underscore the richness and variety inherent in the world of crystals. This deeper exploration into crystal formation reveals that the journey from disorder to order can be far more creative than previously imagined.
Looking to the Future
This study does more than just alter scientific perceptions of crystals; it paves the way for developing new materials with unique properties. Understanding crystal growth could contribute to the advancement of photonic bandgap materials, essential for controlling light in applications such as lasers, solar panels, and fiber-optic cables.
Crystals may appear static and silent, but within them lies a dynamic world of motion, transformation, and discovery. With each new structure uncovered—like Zangenite—that world becomes even more intriguing.
Research findings are available online in the journal Nature Communications.
Note: The article above is provided by The Brighter Side of News.
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