50 research outputs found
High-pressure polymeric nitrogen allotrope with the black phosphorus structure
Studies of polynitrogen phases are of great interest for fundamental science
and for the design of novel high energy density materials. Laser heating of
pure nitrogen at 140 GPa in a diamond anvil cell led to the synthesis of a
polymeric nitrogen allotrope with the black phosphorus structure, bp-N. The
structure was identified in situ using synchrotron single-crystal X-ray
diffraction and further studied by Raman spectroscopy and density functional
theory calculations. The discovery of bp-N brings nitrogen in line with heavier
pnictogen elements, resolves incongruities regarding polymeric nitrogen phases
and provides insights into polynitrogen arrangements at extreme densities
Synthesis of rare-earth metal compounds through enhanced reactivity of alkali halides at high pressures
Anionic Nââ Macrocycles and a Polynitrogen Double Helix in Novel Yttrium Polynitrides YNâ and YâNââ at 100 GPa
Two novel yttrium nitrides, YN(6) and Y(2)N(11), were synthesized by direct reaction between yttrium and nitrogen at 100â
GPa and 3000â
K in a laserâheated diamond anvil cell. Highâpressure synchrotron singleâcrystal Xâray diffraction revealed that the crystal structures of YN(6) and Y(2)N(11) feature a unique organization of nitrogen atomsâa previously unknown anionic N(18) macrocycle and a polynitrogen double helix, respectively. Density functional theory calculations, confirming the dynamical stability of the YN(6) and Y(2)N(11) compounds, show an anionâdriven metallicity, explaining the unusual bond orders in the polynitrogen units. As the charge state of the polynitrogen double helix in Y(2)N(11) is different from that previously found in Hf(2)N(11) and because N(18) macrocycles have never been predicted or observed, their discovery significantly extends the chemistry of polynitrides
High-pressure hP3 yttrium allotrope with CaHg2-type structure as a prototype of the hP3 rare-earth hydride series
Revealing Phosphorus Nitrides up to the Megabar Regime: Synthesis of αâ-P3N5,ÎŽ-P3N5 and PN2
Polytypism of Incommensurately Modulated Structures of Crystalline Bromine upon Molecular Dissociation under High Pressure
Polytypism of incommensurately modulated structures was hitherto unobserved.
Here, we found the phenomenon in simple halogen systems of bromine and iodine
upon molecular dissociation in the solids under pressure. Single-crystal
synchrotron X-ray diffraction in laser heated diamond anvil cells pressurised
up to 112 GPa revealed a number of allotropes of bromine and iodine including
polytypes of Br-III{\gamma} (Fmmm(00{\gamma})s00) with {\gamma} varying within
0.18 to 0.3