title: New cubic phase of Li3N: stability of the N3- ion to 200 GPa.
abstract: Diamond-anvil cell experiments augmented by first-principles calculations have found a remarkable stability of the N(3-) ion in Li3N to a sixfold volume reduction. A new (gamma) phase is discovered above 40(+/-5) GPa, with an 8% volume collapse and a band gap quadrupling at the transition determined by synchrotron x-ray diffraction and inelastic x-ray scattering. gamma-Li(3)N (Fm3m, Li(3)Bi-like structure) remains stable up to 200 GPa, and calculations do not predict metallization until approximately 8 TPa. The high structural stability, wide band gap, and simple electronic structure make this N(3-) based system analogous to lower valency compounds (MgO, NaCl, Ne), meriting its use as an internal pressure standard.
authors.affiliation: Lawrence Livermore National Laboratory, California 94550, USA.
authors.forename: A
authors.initials: A
authors.lastname: Lazicki
authors.forename: B
authors.initials: B
authors.lastname: Maddox
authors.forename: W J
authors.initials: WJ
authors.lastname: Evans
authors.forename: C-S
authors.initials: CS
authors.lastname: Yoo
authors.forename: A K
authors.initials: AK
authors.lastname: McMahan
authors.forename: W E
authors.initials: WE
authors.lastname: Pickett
authors.forename: R T
authors.initials: RT
authors.lastname: Scalettar
authors.forename: M Y
authors.initials: MY
authors.lastname: Hu
authors.forename: P
authors.initials: P
authors.lastname: Chow