For the measurement of conductivity of the FATO nanoparticles, the dried powder from 10 ml of nanoparticle dispersion was pressed into a 7.3 mm diameter pellet of approximate thickness of 1 mm at 460 MPa for 1 hour before being sputtered with platinum. The conductivity was then determined via potentiostatic electrochemical impedance spectroscopy between 1 MHz and 100 mHz.