Crystalline Nitridophosphates by Ammonothermal Synthesis

Abstract

Nitridophosphates are aw ell-studied class of compounds with high structural diversity.H owever,t heir synthesis is quite challenging, particularly due to the limited thermal stability of starting materials like P 3 N 5 .T ypically,i tr equires even high-pressuret echniques (e.g. multianvil) in most cases.H erein, we establish the ammonothermal method as av ersatile synthetic tool to access nitridophosphates with different degrees of condensation. a-Li 10 P 4 N 10 , b-Li 10 P 4 N 10 ,L i 18 P 6 N 16 ,C a 2 PN 3 ,S rP 8 N 14 ,a nd LiPN 2 were synthe-sized in supercritical NH 3 at temperatures and pressures up to 1070 Ka nd 200 MPa employing ammonobasic conditions. The products were analyzed by powder X-ray diffraction, energy dispersive X-ray spectroscopy,a nd FTIR spectroscopy. Moreover,w ee stablished red phosphorus as as tartingm aterial for nitridophosphate synthesis instead of commonly used and not readily availablep recursors, such as P 3 N 5 .T his opens ap romisingp reparativea ccess to the emerging compound class of nitridophosphates.

Sr3P3N7: Complementary Approach by Ammonothermal and High‐Pressure Syntheses

“…Two of these dreier ‐rings, which are structurally related to each other by a rotating mirror axis (2/ m ), are connected through two common corners forming an additional vierer ‐ring. The resulting [P 6 N 16 ]‐units were already found in Li 18 P 6 N 16 as non‐condensed [P 6 N 16 ] 18− anions . In the title compound these subunits are connected by two common corners on each side, forming infinite chains.…”

“…In 1997 Jacobs and co‐workers used this approach to synthesize K 3 P 6 N 11 . In the meantime, the ammonothermal method enabled synthesis of nitridophosphates with isolated tetrahedra units, chains, layers and frameworks . Even nitridophosphates like SrP 8 N 14 or Li 18 P 6 N 16 , which were so far only accessible by the high‐pressure multianvil approach, could be synthesized under ammonothermal conditions in high yield, simplifying the investigation of their physical properties significantly.…”

Nitridophosphate‐Based Ultra‐Narrow‐Band Blue‐Emitters: Luminescence Properties of AEP8N14:Eu2+ (AE=Ca, Sr, Ba)

“…Future studies may thus focus on an alternative synthetic access in order to provide the preconditions for industrial application. Ammonothermal synthesis appears promising, as such syntheses of partially crystalline SrP 8 N 14 have already been reported . Moreover, such methods could provide sufficient sample quantities for a more precise characterization of the luminescence performance, meaning for example, temperature‐dependent emission spectra.…”

Ammonothermal Synthesis of Ba2PO3N – An Oxonitridophosphate with Non‐Condensed PO3N Tetrahedra

“…atomic ratio of tetrahedra centers to ligand) could be realized. Here, a great structural diversity ranging from non‐condensed tetrahedra groups up to network structure types, exhibiting values for κ from 1/3 to 4/7, was observed . Compared to other synthetic methods towards nitridophosphates, such as condensation reactions, synthesis in pressure ampoules or high‐pressure synthesis using the multianvil technique, the ammonothermal method exhibits significant advantages .…”

“…Compared to other synthetic methods towards nitridophosphates, such as condensation reactions, synthesis in pressure ampoules or high‐pressure synthesis using the multianvil technique, the ammonothermal method exhibits significant advantages . This includes the prevention of thermal decomposition of the target compounds, the use of simple starting materials including red phosphorus (P red ) as well as large sample volumes for a detailed characterization of their materials properties …”