RARE-EARTH AND TRANSITION-METAL ION CENTERS IN LINBO3

In this work the present state of art about the rare earth and transit ion metal ion centers phenomenon in LiNbO3 has been analyzed. Particul ar emphasis has been given to lanthanide trivalent rare earth ions (Pr 3+, Nd3+, Eu3+ Dy3+, Ho3+, Er3+, Tm3+ and Yb3+) and to the Cr3+ ion, w here most of information has been reported. The structure of these cen ters is consistent with different off-centered positions of the optica lly active ions inside the Li+ octahedral site. Stoichiometry and codo ping effects on the center distribution are discussed. Finally, possib le models to explain the origin of the different centers are discussed . (C) 1998 Elsevier Science B.V. All rights reserved.