The change in bulk modulus of anatase as a function of grain size. Closed symbols show Al-Khatatbeh’s results^[32] (circles) and those of the microcrystalline TiO₂ anatase (square) and 6 nm nc-nc-TiO₂ nantase (triangle). The bulk modulus of anatase is size-independent in at least two regions: from microcrystalline size down to 40 nm and from 6 nm to 20 nm. The region between 20 nm and 40 nm indicates a transition region for nc-TiO₂ anatase. Reprinted with permission from Ref. [32], Copyright (2012) by the American Chemical Society.