Phase relaxation in disordered nuclear paramagnets

A new method for the construction of main correlation functions of nuclear paramagnets has been developed on the basis of the combination of the projection technique and cumulant expansions. It gives satisfactory results for the free induction decay and resonance line shape function in magnetically concentrated crystals. Polarization transfer in magnetically dilute crystals has been taken into account. It significantly retards a decrease in the FID at times longer than the phase relaxation time $T_2$. The FID remains mainly monotonic in contrast to magnetically concentrated crystals, where the FID oscillates. The results have been compared to the existing experimental data.