Investigation of the system ThO2–NpO2–P2O5. Solid solutions of thorium–neptunium (IV) phosphate–diphosphate

Preparation and properties of tetravalent protactinium phosphates

This chapter focuses on the solid state structural chemistry of actinide materials as determined by single–crystal X–ray diffraction, single–crystal neutron diffraction, powder X–ray diffraction, and powder neutron diffraction techniques. Since Burns’ chapter, Structural Chemistry, was published in the 1986 edition of this work, significant improvements in crystallographic technology and instrumentation have advanced the field of solid state chemistry. Some of the most dramatic changes have been in computer technology and software, making the data collection, reduction, and refinement processes highly automated and simplified. As a consequence, X–ray diffractometers have become nearly ubiquitous in research departments globally and neutron–scattering resources have become more advanced and accessible, resulting in the elucidation and publication of a greater number of additional actinide structures since the last edition; these structures are the focus for this chapter.

Actinide Structural Chemistry

Prior to the isolation of approximately 100 g of 231Pa by U.K. scientists in 1960, the preparative chemistry of protactinium had been little investigated and few compounds were known. As a consequence of the availability of macro-quantities of a nuclide with a reasonably long half-life, world-wide interest was generated in the chemistry of protactinium. Much of this has been directed at the preparation of the metal and a wide range of compounds, and investigations of their chemical and physical properties. The currently available methods for the preparation of metallic protactinium are discussed together with publications dealing with its chemical properties. Details are provided of the preparative routes to all protactinium compounds, particular attention being given to those pentahalides and tetrahalides which are valuable starting materials for the preparation of other classes of compounds.

J. M. Dartyge

Papers

Phosphates de protactinium pentavalent

Phosphates of pentavalent protactinium