The magnetic nuclear spin-lattice relaxation has been studied in PrF3. It was found that Pr-141 spin-lattice relaxation rate is untypically high for the Van Vleck insulator. According to all existing experimental data the only relaxation channel for enhanced nuclear moments at low temperatures is interaction with paramagnetic impurities and typical nuclear relaxation rate in rare earth Van Vleck paramagnets at liquid helium temperatures is 1 s(-1). The measured value is 100 s(-1). At the assumption that relaxation is caused by the strong 4f-4f cooperative interaction mediated by phonons Ill, we measured Pr-141 relaxation rates in a number of PrxLa1-xF3 samples and found that in diluted samples relaxation slows down to the usual for insulators values.

Nuclear pseudoquadrupole resonance of 141 Pr in Van Vleck paramagnet PrF 3 has been observed in singlecrystal and micro- and nanopowder samples at a temperature of 4.2 K. The spectra of nuclear pseudoquadrupole resonance of 141 Pr, as well as the spin-spin and spin-lattice relaxation parameters, have been obtained. The parameters of the nuclear spin Hamiltonian have been determined. It has been found that the parameters of the crystal electric field in nanocrystals differ strongly from those in microcrystals.

Nuclear pseudoquadrupole resonance of 141Pr in Van Vleck paramagnet PrF3 has been observed in singlecrystal and micro- and nanopowder samples at a temperature of 4.2 K. The spectra of nuclear pseudoquadrupole resonance of 141Pr, as well as the spin-spin and spin-lattice relaxation parameters, have been obtained. The parameters of the nuclear spin Hamiltonian have been determined. It has been found that the parameters of the crystal electric field in nanocrystals differ strongly from those in microcrystals.