LATTICE LOCATION OF PR3+ IONS IN LINBO3

Site-selective spectroscopy and Rutherford backscattering spectrometry /channelling techniques are combined to carry out a systematic investi gation of the local structure of the different Pr3+ centers formed in LiNbO3. Channeling experiments reveal that Pr3+ ions are located in Li + octahedral sites, but off-center from the regular Li+ position towar ds the nearest oxygen plane by about 0.4 Angstrom. Site-selective spec troscopy experiments detect the presence of at least four non-equivale nt Pr3+ centers. The spectroscopic properties of these centers are als o analyzed and explained as a result of the previously mentioned displ acements.