  Controlled chemical transformation of nanostructures is a promising technique
to obtain precisely designed novel materials which are difficult to synthesize
otherwise. We report high-temperature vapor phase anion exchange reactions to
chemically transform II-VI semiconductor nanostructures (100-300 nm length
scale) while retaining the single crystallinity, crystal structure, morphology
and even defect distribution of the parent material via atomic templating. The
concept of atomic templating is employed to obtain kinetically controlled,
thermodynamically metastable structural phases such as zincblende CdSe and CdS
from zincblende CdTe upon complete chemical replacement of Te with Se or S. The
underlying transformation mechanisms are explained through first-principles
density functional theory calculations. Atomic templating is a unique path to
independently tune materials phase and composition at the nanoscale allowing
synthesis of novel materials.
