Conventional and cryo-synchronous luminescence spectra of orthorhombic calcium titanate

We report, for the first time, characterization of electronic midgap states in the nanocrystalline orthorhombic calcium titanate by synchronous luminescence spectroscopy at 77 K versus the “conventional” PL emission and excitation spectroscopy, and by the complementary spectroscopic and structural methods. We also report the radiative transitions from the three distinct electronic midgap states in nanocrystalline orthorhombic calcium titanate at the extrabandgap and subbandgap photoexcitation. The emission peaks of the nanocrystalline orthorhombic CaTiO3 obtained in the cryo-synchronous luminescence experiments are significantly narrower and much better resolved than those obtained in the “conventional” PL emission spectroscopy experiments under the same conditions.