Reversible Polymerization of Adamantane‐type [P₄N₁₀]¹⁰⁻ Anions to Honeycomb‐type [P₂N₅]⁵⁻ Layers under High‐Pressure

Abstract

The high-pressure polymorph Li P N of Li P N (="2 Li P N ") was synthesized by high-pressure/high-temperature reaction of LiPN and Li PN or β-Li P N at 9 GPa, using the Li N self-flux method in a Walker-type multianvil assembly. Li P N is the first lithium nitridophosphate with a layered structure and is made up of corner sharing PN tetrahedra forming a corrugated honeycomb-type layer of linked sechser-rings in chair conformation. The arrangement of the P atoms is analogous to that of black phosphorus. The structure was elucidated from single-crystal X-ray data. To confirm the structure Rietveld refinement, Li, Li and P solid-state NMR spectroscopy were conducted. To corroborate Li P N as the corresponding high-pressure polymorph of β-Li P N DFT calculations and temperature dependent X-ray powder diffraction were carried out. DFT calculations estimated the transition pressure to 6.5 GPa (without accounting for temperature), which is in line with the synthesis pressure.

Ammonothermal Synthesis of Nitrides: Recent Developments and Future Perspectives

“…[102][103][104] The former two compounds contain adamantane-like anions, with structurala nalogy to the lithium nitridophosphate Li 10 P 4 N 10 . [105][106][107] On the other hand, K 3 P 6 N 11 represents the sole ammonothermally synthesized nitridophosphate so far,a nd can be obtained from P 3 N 5 and KNH 2 at 773 Ka nd 600 MPa NH 3 as microcrystallinep owder. [95] The anionic P-N framework is analogous to the Si-N framework in the above mentioned K 3 Si 6 N 5 (NH) 6 ,f orming corner-sharing PN 4 tetrahedra, which can be separated in three symmetry equivalent chains along [1 00], [0 10], and [0 01]( Figure 4).…”

“…Reactions of P 3 N 5 with MNH 2 (M=Na, Rb, Cs) at 670–870 K yielded single crystals of imides and imidonitrides Na 10 [P 4 (NH) 6 N 4 ](NH 2 ) 6 ⋅ 0.5 NH 3 , Rb 8 [P 4 N 6 (NH) 4 ](NH 2 ) 2 and Cs 5 [P(NH) 4 ](NH 2 ) 2 . The former two compounds contain adamantane‐like anions, with structural analogy to the lithium nitridophosphate Li 10 P 4 N 10 . On the other hand, K 3 P 6 N 11 represents the sole ammonothermally synthesized nitridophosphate so far, and can be obtained from P 3 N 5 and KNH 2 at 773 K and 600 MPa NH 3 as microcrystalline powder .…”

SrH4P6N12 and SrP8N14: Insights into the Condensation Mechanism of Nitridophosphates under High Pressure

“…As examples, the parentc ompounds, P 3 N 5 ,H PN 2 (i.e.,P N(NH))a nd HP 4 N 7 (i.e.,P 4 N 6 (NH)) can be named, showingr are structural motifs like triply bridging N [3] atoms or edge-sharing tetrahedra. [15][16][17][18] Another synthesis route is based on thermal dissociation of metal azides. [5,10] Furthermore, calculations predicted the existence of afurtherhigh-pressure polymorph, d'-P 3 N 5 ,exhibiting trigonal bipyramids as fivefold coordination spheres of P, as well as sixfold coordinated Pi na no ctahedral environment.…”

“…The most common method is the reaction of metal nitrides with binary P 3 N 5 , exemplified for the synthesis of M 2 PN 3 ( M =Mg, Ca) . Derived from this method, application of a Li 3 N flux allows for the synthesis of lithium nitridophosphates, like Li 18 P 6 N 16 , Li 12 P 3 N 9 , or Li 10 P 4 N 10 . Another synthesis route is based on thermal dissociation of metal azides.…”

Nitridophosphates: A Success Story of Nitride Synthesis

“…The structural relation to oxosilicates is given through the networksb uilt up from tetrahedra,a s the example of the binary parent compounds P 3 N 5 and SiO 2 shows. [2][3][4][5][6][7][8][9] Periodic Table of the Elements highlightingall electropositive elements stabilizedi nnitridophosphates. Rare-earth elements in hatched boxes have not been incorporated yet but owing to similar chemical behavior to the other rare-earth elements,t heir incorporation is expected to be feasible.…”