Understanding the Influence of Finite Size on Phase Transitions and Intercalation Processes in Vanadium Oxides
In physics and chemistry a “phase transition,” occurs when a material changes form, say liquid to gas, as in evaporation. Ice, a solid, is what water becomes after the phase transition we call freezing. Sarbajit Banerjee is studying phase transitions in an exotic substance called vanadium dioxide, Vanadium is a soft, silvery gray metal. It’s never found in nature in its pure state, but always has a layer of oxidation - rust, if it were iron. The chemical symbol for this oxidized form of vanadium is VO2. Banerjee’s research is aimed a developing a good understanding of how VO2 switches between two closely related but subtly different forms as a result of changes in temperature, as well as a process called hysteresis, that occurs in VO2 during phase transition. (Hysteresis is the “lagging of an effect behind its cause;” especially the phenomenon in which the magnetic induction of a material lags behind a changing magnetic field in which it’s placed.) While many materials undergo phase transitions, VO2 is special in that the phase transition abruptly causes a pronounced change in the electrical properties, transforming a rubber-like insulator to a lustrous metallic phase. But if this research weren’t complicated enough, Banerjee intends to study these processes in nanometer-sized chunks of VO2. A nanometer is one billionth of a meter - incredibly tiny. Many scientists today are interested in nanomaterials because matter tends to behave differently - that is, it exhibits different electromagentic properties—when reduced to extremely tiny packets of just a few atoms. So Banerjee intends to create VO2 and related material on the nanoscale and then introduce additional “foreign” atoms - a process called doping - and study the effects on phase transitions and the stability of the resulting material. While his goal in performing this basic research is simply to better understand the behavior of VO2 and related material at the nanoscale, who knows - one day he might just stumble across an easy-to-manufacture, room-temperature superconductor or a highly efficient window coating that allows dramatic reduction in the heating and cooling of buildings. And that could change everything.
The educational component of Sarbajit Banerjee’s Cottrell Scholar award aims to ignite a genuine excitement about science in undergraduate students. “A major worry is that our introductory chemistry courses are failing to convey the excitement of discovery that underlies science, instead presenting science as a tortuous and tedious process involving concepts that must be memorized and equations that must be manipulated while being vigilant for the ever-lurking possibility of the ‘trick’ question,” he says. “What is lost all too easily is perspective of the broader goals of the scientific enterprise and the interconnectedness of scientific and technological disciplines that undergirds modern research.” Banerjee’s project seeks to establish an introductory open-ended laboratory course to address real-world challenges, drawing upon the passion students have for topics such as energy research and environmental science. The course will interface through joint projects with similar laboratory courses offered in Electrical and Biomedical Engineering, and even with a studio course offered by UB’s Department of Visual Studies. “By building an active learning community drawing upon authentic practice,’ he says,” we’ll strive to develop close mentoring relationships, promote cooperative learning, and inculcate students with higher-order reasoning skills that will inspire them to seek out undergraduate research experiences in research laboratories.” In other words, he intends to help students think like scientists, rather than merely absorb facts about science.