Rare earth doping into optical nonlinear nanocrystalline phase in transparent TeO2-based glass-ceramics

Optically transparent rare earth (Ln)-doped glass-ceramics based on the system K2O-Nb2O5-TeO2 have been prepared, and the effect of Ln additions on crystallization behaviors and optical properties has been examined. The lattice constant of the TeO2-based metastable optical nonlinear nanocrystalline phase (average particle size: < 60nm) with basically a cubic structure in the glass-ceramics decreases due to Ln additions, and the incorporation of Ln(3+) with small ionic radii such as Er3+ or Tm3+ stabilizes the metastable crystalline phase, giving the significant effect on the crystallization and phase transformation behaviors in TeO2-based glasses. From the phonon sideband spectra associated with the (5)Do --> F-7(0) transition of Eu3+, it is found that both phonon energy and electron phonon coupling strength for transparent glass-ceramics are smaller than those in the precursor glass. The upconversion fluorescence intensity around 550 nm due to the S-4(3/2) --> I-4(15/2) transition of Er3+ is strong (about 20 times) compared with the precursor glass. (C) 2001 Elsevier Science Ltd. All rights reserved.