The Robinson group's work on "nano-hamburgers" is featured in Scientific American, Israel ed.
The work features their nano-hamburger metastable structures, made through cation exchange. In this work, the group developed a means to strain tune the plasmon in Cu2-xS, demonstrating a means to decouple the optical properties (plasmon) from the crystal phase. Using Cu-Zn-S nano-heterostructures that they built using cation exchange, they find, to their surprise, that the center layer of Cu2-xS undergoes a solid-solid phase transformation from the initially metastable phase (x=1.81) to its lower energy phase of djurleite (Cu1.94S), but then returns back again to the higher energy phase x=1.81 due to strain stabilization with the epitaxial interfaces between layers. The plasmon, however, does not obey the crystal phase; the metastable phase no longer supports a plasmon in the smaller structures. This work demonstrates novel routes to composition control in nanoparticles through chemical transformation.
Nano Letters article can be found here:
D.-H. Ha, A.H. Caldwell, M.J. Ward, S. Honrao, K. Mathew, R. Hovden, M.K.A. Koker, D.A. Muller, R.G. Hennig, and R.D. Robinson, “Solid-Solid Phase Transformations Induced through Cation Exchange and Strain, in 2D Heterostructured Copper Sulfide Nanocrystals,” Nano Letters 14, 7090–7099 (2014).
Scientific American Israel article found here: