Investigation of valent states of sup(237)Np ions formed due to α-decay of sup(241)Am in CeAlOΛ3 lattice by nuclear gamma-resonance spectroscopy

Method of nuclear γ-resonance spectroscopy was used to analyze valent Np states formed after sup(241)Am α-decay and to study the position of daughter sup(241)Am atom in CeAlO3 matrix related to the categ.ory of rare earth perovskites. NGR spectra of sup(241)Am source in CeAlO3 were measured at 77 and 190 K with NpO2 absorber. It is shown that ma ority of Np ions (approximately 70%) after moderation in CeAlO3 lattice have Np4+ valent state. Analysis of spectrum showed that Ce ion in CeAlO3 lattice points is substituted for Np3+ ion in the end of the path. Np4+ ions in nuclear gamma-resonance spectra are characterized by two lines: one line with 1.7 mm/s shift and without quadrupole splitting and another one has 8.5 mm/s shift and parameters of quadrupole splitting e2q Q/4=23.0 mm/s, n=0.49 at 77 K. Anaiysis of these data shows that shift value (8.5 mm/s) corresponds to more ionic Np state; parameters of quadrupole interaction shown that deviation in the nearest surrounding from cubic symmetry is significant and the symmetry formed at that is lower than Csub(3V) group. It means that oxygen vacancy occurs in the lattice in the nearest surrounding of Np ions