Compressibility of Nanocrystalline TiO2 Anatase

Using high-resolution, synchrotron-based powder X-ray diffraction (XRD), we have studied the high-pressure behavior of the anatase phase of nanocrystalline TiO2 (nc-TiO2) under hydrostatic conditions. We find that for anatase with a grain size larger than ∼40 nm, the room-pressure bulk modulus K 0 remains constant at ∼200 GPa to within experimental uncertainties. An ∼15% decrease in K 0 is observed for grains that are ∼20 nm in size and remains unchanged for grains down to 6 nm in diameter, indicating a rapid increase in compressibility for nc-TiO2 anatase between 40 and 20 nm.