Massive metal—insulator transitions in nanostructures of a 1-D vanadium oxide bronze

Sarbajit Banerjee, SUNY at Buffalo, DMR 0847169 The electrical conductivity of δ-KxV2O5 vanadium oxide bronze nanowires is found to dramatically and abruptly increase at temperatures in the range between 90—120 °C. Essentially, the nanowires are suddenly transformed from being insulating (akin to wood) to being metallic (akin to copper wires) upon heating.

Remarkably, the sudden transition is marked by a four-orders of magnitude change in the electrical resistance of the nanowires.

The metal—insulator transition can be induced not just by heating but also by applying a voltage or flowing a current through the nanowires.

Potential applications as switching elements, window coatings for “smart” windows that enable the energy efficient heating/cooling of buildings, and field effect transistors for the next generation of electronics.

The figure schematically depicts a single δ-KxV2O5 nanowire aligned between gold electrodes; the crystal structure is shown as an inset (VO6 polyhedra depicted in green with intercalated potassium ions in purple) along with electrical transport data indicating the switching of the nanowire from an insulator to a conductor. The background image shows examples of the δ-KxV2O5 nanowires synthesized in our laboratories.

Massive metal—insulator transitions in nanostructures of a 1-D vanadium oxide bronze

Sarbajit Banerjee, SUNY at Buffalo, DMR 0847169

The Banerjee group participated in weekly visitations to School 19, Native American Magnet School-an urban, high-needs public school in Buffalo. Activities included help with experiments, afterschool science club, and an annual “science fun” night (left).

The PI was awarded a Faculty Mentor Award by the UB Bridge to the Doctorate Program for encouraging the participation of underrepresented minorities in doctoral programs-the only assistant professor in the university to be awarded this distinction. The PI is mentoring three Hispanic-American graduate students and one African-American graduate student.

Sarbajit Banerjee is co-PI of a NSF REU site funded by the chemistry division. The PI mentored 4 undergraduates over the last year at various times.

The Banerjee group hosted two Buffalo Public Schools teachers over the last year, who participated in research and professional development activities

The vanadium oxide technologies are being commercialized by Graphene Devices Limited, a local startup company in the WNY area.