Mössbauer Spectroscopy in Actinide Research

Abstract

Actinide compounds /Mössbauer spectroscopy /Electronic structure /Crystal structure /Magnetism L Introduction Π. Information accessible to Mössbauer spectroscopy ΙΠ. Mössbauer spectroscopy in the actinide elements 1. Introduction 2. Reported resonances 3. Other possibilities IV.Electionic configuration, bonding and magnetic properties 1. Introductory survey of theoretical concepts 2. Chemical information from isomer shift data 3. Chemical information from electric field gradient data 4. Chemical information from magnetic hyperfine data V. Structural information: Crystallographic and magnetic phase transitions and structures VI. Radiation effects in actinide materials: After-effects of nuclear decays and of nuclear reactions; self-irradiation effects VII. Conclusions AbstractThe principles and possibilities of Mössbauer spectroscopy in actinide compounds are reviewed. A survey of applications of chemical character to problems of electronic structure, bonding properties, magnetism and phase transitions is given in order to illustrate the possibilities of Mössbauer spectroscopy. In particular, the recently very active problem of the elucidation of the type of phase transition occurring at low temperature in Np0 2 (~ 25 K) and Am0 2 ( ~ 10K) is discussed on the basis of recent experimental results using the 23 'Np and "'Am Mössbauer resonances. Problems connected with after-effects of nuclear decays, radiation damage and self-irradiation effects are emphasized with the aid of a series of new experimental results.

Advances in Chemistry of the Actinide Elements

“…A substantial number of complex oxides of Np(VII) have been prepared, but attempts at fluorides or oxyfluorides have not succeeded [18]. A powerful tool for study of neptunium chemistry -especially appropriate in view of its multiplicity of oxidation states -is Mössbauer spectroscopy, for which the isomer shifts of the metal, intermetallic Compounds, and many Np(III) through Np(VII) Compounds show clearly the tetravalent nature of the metal and the degrees of ionic/covalent behavior of its Compounds [19,20].…”

X-ray Diffraction, Mössbauer Spectroscopy, Magnetic Susceptibility, and Specific Heat Investigations of Na4NpO5 and Na5NpO6

“…Finally, looking at general trends among heptavalent neptunium compounds, Friedt et al reported an increasing linear variation of the quadrupole coupling constant as a function of isomer shift 30,37 through the series of compounds Li 5 NpO 6 , Cs 3 NpO 5 , Rb 3 NpO 5 , CsNpO 4 , and RbNpO 4 , which was related to the increasing occupation of the 5f and 6d atomic orbitals. The parameters reported by Jovéet al for Ba 2 NaNpO 6 and K 3 NpO 5 , 24 and those found herein for the Na 5 NpO 6 compound, fit this trend very well as shown in Figure 7.…”

Moessbauer spectroscopy

“…Concerning the actinide elements, reviews have been reported by Friedt (90) and by Potzel et al (255). A review of 197Au Mossbauer spectroscopy is given by Parish (244).…”