High-pressure behavior of SnO2 nanocrystals

High-pressure behaviors of bulk and nanocrystalline SnO2 samples have been studied by in situ high-pressure synchrotron radiation x-ray diffraction measurements up to about 40GPa at ambient temperature. It is found that the smaller the nanocrystal SnO2, the higher the onset transition pressure for the rutile-to-cubic phase transformation in SnO2. The enhancement of the transition pressure is mainly due to the surface energy differences between the rutile and cubic phases and/or the enhancement of energy band gap when the SnO2 crystallite size gets smaller.