NGR emission spectroscopy of 237Np in PuO2

Emission nuclear gamma-resonance 237Np spectra of 241AmO2 solid solutions in PuO2 with 0.6-11 at. % americium content, prepared according to usual technique of oxalate deposition and calcination and by the method of fluorooxygen exchange in LiF-NaF melt were measured in 77-296 K range. NGR spectra were used to determine 237Np valent states and parameters of superfine interaction observed in plutonium dioxide during 234Am α-decay, their behaviour depending on impurity content and matrix stoichiometry. The decisive effect of the type of conductivity (hole or electron) of plutonium dioxide on radiogenic neptunium distribution according to valent states is shown. Possible reasons of change of neptunium superfine interaction parameters, depending on temperature are discussed