Jul 03, 2018· 2.3.1. Structure and Property Characterization . We observed the morphology of CaCO 3, TiO 2, and CaCO 3-TiO 2 composite particles by scanning electron microscope (SEM, S-3500N, , Tokyo, Japan) under an energy dispersive spectroscope at 5.0 kV and transmission electron microscope (TEM, FEI Tecnai G2 F20, Portland, OR, USA) under an acceleration voltage of 300 kV.