Characterization of novel lanthanum nitrides

High pressure chemistry and physical properties of rare earth metal nitrides are almost unknown. The novel LaN2 phase with [N4] stars synthesized by our group (and first studied at ID15b) not only expands the list of unusual nitrogen species formed under high pressure, but also opens up the question of stabilization of the uncommon La2+ lanthanum oxidation state under high pressure. Here, we propose a single-crystal X-ray diffraction (SCXRD) study at ID15b in combination with X-ray absorption near edge structure (XANES) study at ID12 of La-N system up to 120 GPa. The goals of this proposal are to 1) determine oxidation state of La in the novel LaN2 phase by XANES, 2) apply SCXRD and XANES to investigate La-N system at 50-120 GPa pressure range to uncover novel structures with more exotic poly-N anionic species and 3) determine equation of states and existence pressures of LaN2 as well as of other novel yet to be uncovered nitrides phases.