  This work reports the results of EPR and NMR study of the Ce3+ incorporation
in LaAlO3 single crystals grown by the micro-pulling-down method in the range
of the Ce concentrations from x=0.1 at.% up to 100 at.%. From EPR measurements,
Ce3+ g tensor parameters were obtained as function of Ce concentration. The g
tensor has orthorhombic symmetry even in the trigonal phase (x < 10 at.%)
suggesting that the incorporation of Ce at La site lowers lattice symmetry near
this ion. The local properties of the La1-xCexAlO3 crystals were further
studied by 27Al and 139La high-resolution NMR measurements. It was found that
139La chemical shift has the Fermi contact interaction origin. It linearly
increases with Ce concentration up to 165 ppm at x = 0.5. Due to this strong
Fermi contact interaction, separated peaks corresponding to different Ce-O-La
spin transfer passways are resolved in the 139La NMR spectra. On the other
hand, no Fermi contact interaction is visible in 27Al NMR spectra. However,
these spectra contain satellite peak which intensity linearly increases with
increase of Ce concentration leaving position of this peak unchanged. This was
interpreted as manifestation of crystal structure modification in vicinity of
Ce ions in agreement with EPR data. Thus, optical properties of Ce3+ in LaAlO3
will be namely determined by the local crystal structure near this ion.
