Spectroscopic properties of Nd ions in nano-perovskite CaTiO3

In this work, we present for the first time the spectroscopic properties of perovskite nanocrystals CaTiO₃: Nd³⁺, measured at room and liquid nitrogen temperature. Samples were prepared by the sol–gel method and annealed at 700 and 1000 °C. The concentration of Nd³⁺ ranged from 0.5% to 5%. Average nanocrystallite size primarily depends on the annealed temperature and is about 25 and 50 nm for 700 and 1000 °C, respectively. The absorption, emission and excitation spectra (monitored at 1078 nm) as well as the decay time profile of the emission from the ⁴F_3/2 energy level of Nd³⁺ are obtained. The increasing amount of Nd³⁺ ions decreases the lifetime of the ⁴F_3/2 level and that changes from 146 μs for 0.5% to 50 μs for 5% of Nd³⁺ concentration. The strongest emission was observed at two regions: 1050–1120 nm and 865–930 nm and was assigned to the ⁴F_3/2→⁴I_11/2 and ⁴F_3/2→⁴I_9/2 transitions, respectively. The spectroscopic quality parameter of neodymium in the CaTiO₃ lattice has been calculated from the emission spectra. The influence of luminescent properties depending on the annealing temperature and concentration of neodymium ions is discussed.