This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: For the first time, researchers at the University of Minnesota Twin Cities have demonstrated that the low-purity iron ore prevalent in Minnesota can be used to create semiconductor-quality iron sulfide, also known as "fool's gold" or pyrite. This discovery could have cost-effective and sustainable applications in future electronic devices and other technologies.
The work is published in the journal Physical Review Applied. Minnesota is one of the largest iron-producing states, accounting for 75% of the nation's ore and generating more than $4 billion in annual revenue. Natural resources such as the Mesabi Iron Range have fueled Minnesota iron production for decades, enabled by the taconite process developed by Edward Wilson Davis at the University of Minnesota.
Pyrite iron sulfide is a unique semiconductor because it absorbs light extraordinarily well and is composed of abundant, nontoxic and cost-effective elements. Synthesizing high-quality semiconducting pyrite directly from an abundant iron resource like the Iron Range is therefore appealing, but semiconductors are extremely sensitive to impurities and defects, making this challenging. In this work, the researchers took iron ore samples directly from the Minnesota Iron Range and demonstrated that they can be used to synthesize semiconductor-quality fool's gold using simple processes.
This discovery took the researchers by surprise. "We realized that pyrite's really not like a typical semiconductor—it is surprisingly immune to impurities," said Chris Leighton, Distinguished McKnight University Professor in the Department of Chemical Engineering and Materials Science and senior author on the paper. "So, we wondered, do we even need the high-purity material that we (and everyone else) had been using to make semiconducting pyrite." The researchers were able to test three different types of iron ore in this process.
It turns out that the one that works best—Direct Reduced Grade Taconite—is one of the most commonly used grades available in Minnesota. "There are all sorts of reasons why you would think this would not be possible," Leighton added. "But during processing, the dirty—or low-purity—iron ores directly from the Minnesota Iron Range were easily converted to semiconductor-quality pyrite with no extra purification steps.
This happens for reasons that we now understand pretty well." This discovery could open up a new revenue stream for a global industry, with a broad spectrum of applications in clean energy technologies based on a natural resource found abundantly in Minnesota. Future applications of this research could include batteries, solar panels, electronics and water-purification processes. The team hopes to continue this research by testing additional types of iron ore, which come in a vast variety of grades.
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