Spectroscopic properties of the CaNb2O6:Pr3+ single crystal

The spectroscopic measurements of the calcium niobate CaNb2O6 (columbite) single crystal doped with trivalent praseodymium ions have been performed. The polarised optical absorption and emission spectra as well as luminescence decay curves of this material have been recorded. The absorption spectra consist of well-resolved transitions from the 3H4 ground state to the 3PJ, 1DJ, 1GJ, 3FJ and 3HJ levels. The strongest bands correspond to the 3H4 → 3P0 and 3H4 → 3F2 transitions. The former band is composed of three components of different intensity. This suggests the existence of three different centers in the CaNb2O6 crystal for the Pr3+ ions that substitute for Ca2+.The emission spectra of the crystal studied show clear temperature and polarisation dependence. The strongest band of the luminescence corresponds to the 1D2 → 3H4 transition at 610 nm with small bandwidth and high intensity. The lifetime of the 1D2 level increases from 59 μs to 78 μs when temperature decreases from 300 K to 50 K.