For over two centuries, scientists have been attempting to grow dolomite, a common mineral found in various geological formations, under laboratory conditions that mimic its natural formation. However, it was not until recently that a team of researchers from the University of Michigan and Hokkaido University in Sapporo, Japan achieved this long-awaited breakthrough. Their success in growing dolomite not only solves the “Dolomite Problem,” a geological mystery, but also holds potential for advancing the development of modern technological materials.
Dolomite is a significant mineral found in landmarks such as the Dolomite mountains in Italy, Niagara Falls, the White Cliffs of Dover, and Utah’s Hoodoos. While it is abundant in rocks older than 100 million years, it is rarely found in younger formations. Scientists have struggled to understand why this mineral becomes less prevalent over time. By unraveling the mystery of dolomite growth in nature, researchers hope to gain insights into crystal growth strategies that can be applied to the production of advanced materials.
The key to successfully growing dolomite in the laboratory was addressing defects in the mineral structure as it forms. When minerals develop in water, atoms typically arrange themselves neatly on the growing crystal surface. However, dolomite’s growth edge consists of alternating rows of calcium and magnesium. In the presence of calcium and magnesium ions in water, these elements randomly attach to the growing dolomite crystal, often in incorrect positions. These defects hinder the formation of additional dolomite layers, decelerating the growth process significantly. Without intervention, it would take millions of years to form a single layer of ordered dolomite.
Fortunately, the defects in dolomite growth are not permanent. Disordered atoms are less stable than those in correct positions, making them susceptible to dissolving when exposed to water. By repeatedly rinsing away these defects through natural processes like rain or tidal cycles, dolomite layers can gradually form over a matter of years. Over millions of years, extensive dolomite formations can accumulate, resulting in geological features like mountains and cliffs.
To accurately simulate dolomite growth, the researchers needed to calculate the strength of interactions between atoms and an existing dolomite surface. Typically, such simulations require extensive computing power due to the exhaustive calculations necessary. However, the team developed software at U-M’s Predictive Structure Materials Science (PRISMS) Center that provided a more efficient approach. The software extrapolates energy calculations for some atomic arrangements based on the symmetry of the crystal structure, enabling rapid simulations over geological timescales. This breakthrough reduced the computational time for an atomic step from thousands of CPU hours to just milliseconds.
To validate their theory, the researchers collaborated with Professor Yuki Kimura from Hokkaido University and postdoctoral researcher Tomoya Yamazaki. They utilized an electron microscope’s ability to split water and dissolve crystals. By delicately pulsing the electron beam over a tiny dolomite crystal submerged in a calcium and magnesium solution, the defects were gradually dissolved away. In just two hours, approximately 100 nanometers of dolomite, equivalent to around 300 layers, had grown. This achievement surpassed any previous attempts to grow more than five layers of dolomite in the laboratory.
Potential Impact on Technological Materials
The findings from the Dolomite Problem carry significant implications for the manufacturing of high-quality materials used in semiconductors, solar panels, batteries, and other technologies. Traditionally, crystal growers have attempted to minimize defects by growing materials at an extremely slow rate. However, the researchers suggest that manipulating the crystal growth process based on their newfound understanding could lead to the production of materials with fewer defects and improved properties.
After centuries of scientific struggle, researchers have successfully grown dolomite in the laboratory, finally resolving the long-standing “Dolomite Problem.” By addressing defects in the crystal structure, the team overcame the limitations that previously hindered dolomite growth. The breakthrough holds promise not only for understanding dolomite formation in nature but also for revolutionizing the production of advanced technological materials. The ability to manipulate crystal growth based on atomic simulations opens new avenues for creating higher-quality materials across various industries.