An Unprecedented AB₂ Tetrahedra Network Structure Type in a High‐Pressure Phase of Phosphorus Oxonitride (PON)

Abstract

Compounds exhibiting AB 2 -type tetrahedral network structures are versatile materials and of great technical importance. First of all microporous zeolites are known for their outstanding absorption properties and catalytic behavior and are therefore extensively used in industrial, agricultural, and laboratory environments. [1] However, the importance of dense AB 2 networks should not be underestimated. SiO 2 and to a minor extent GaPO 4 are applied in piezoelectric devices, such as pressure sensors and microbalances, [2] while quartz-like compounds in general, including phosphates such as AlPO 4 and BPO 4 , can also be used for second-harmonic generation (SHG) purposes. [3,4] Owing to the variety of applications, widespread research into novel AB 2 -type structures was conducted, including the prediction of more than two million unique prospective crystal structures for zeolites. [5] However, only a minute subset of possible structures has been realized to date. In this search for new structure types, we have directed our attention to the system P-O-N, which is isoelectronic to silica. The inclusion of nitrogen provides additional structural flexibility, which theoretically opens up an even wider range of possible structure types. The few known compounds in this system include the first nitridic zeolites NPO [6] and Ba 19 P 36 O 6+x N 66Àx Cl 8+x (x % 4.54) [7] as well as the nitridic clathrate P 4 N 4 (NH) 4 (NH 3 ) [8] and the polymorphs of PON exhibiting cristobalite-, [9] quartz-, [10] and moganite-type [11] structures. Glassy compounds in the system Li-Ca-P-N also exhibit desirable properties, such as a high hardness and refractive index. [12] The great potential for novel structure types in this system is offset by difficulties in preparation, such as thermal decomposition, low reactivity, and a low degree of crystallinity. To circumvent the mentioned problems, we developed a novel synthetic approach, utilizing an amorphous single-source precursor. Herein, we report on a new high-pressure phase of phosphorus oxonitride PON. Since this is the fourth known polymorph of PON, we propose the name d-PON. Unlike the quartz and moganite polymorphs, it is not directly accessible by treating cristobalite-type PON under high-pressure/high-temperature conditions. This result hints at the possibility of d-PON being thermodynamically metastable at these conditions. Instead, we prepared d-PON by carrying out the final thermal

Li+ Ion Conductors with Adamantane‐Type Nitridophosphate Anions β‐Li10P4N10 and Li13P4N10X3 with X=Cl, Br

“…[12] To prevent thermald issociation at higher temperatures, the multi-anvil technique has emerged as apowerful tool, and has led to nitridophosphates with unprecedented topologies and properties. [9,[12][13][14] To date, an umber of lithium nitridophosphates have been obtained at reactiont emperatures below 850 8C. [6,[15][16][17][18][19] Reactiono ft he binary nitrides P 3 N 5 and Li 3 Nb etween 620 and 800 8Cl ed to four lithium nitridophosphates with different complex P/N anions in am atrix of Li + ions.…”

Rare‐Earth‐Metal Nitridophosphates through High‐Pressure Metathesis

“…[10] This clathrate has been discussed as ap ossible gas-storage material. [13][14][15][16][17] However,t he structural elucidation can be laborious owing to microcrystalline products that require elaborate powder diffraction and electron microscopy methods for structure determination. [12] However,t he accessibility of nitridophosphates through conventional solid-state synthesis is limited by the thermal stability of common starting materials like P 3 N 5 ,which tend to decompose below the crystallization temperature of the targeted phases.High-pressure synthesis using the multianvil technique has promoted the exploration of alkaline earth nitridophosphates like MP 2 N 4 (M = Be,Ca, Sr, Ba) and highpressure polymorphs of the silica analogous PON.…”

“…[11] Furthermore,t he zeolitic Ba 3 P 5 N 10 Br:Eu 2+ is ap romising luminescent material for solid-state lighting that emits natural white light. [14,16] Synthetic success with alkali-metal and alkaline-earthmetal nitridophosphates could not yet be expanded to trivalent rare earth metals.I no rder to tackle the aforementioned problems,w et ailored an ew synthetic pathway by means of high-pressure metathesis and targeted rare-earthmetal nitridophosphates as am odel system. [13][14][15][16][17] However,t he structural elucidation can be laborious owing to microcrystalline products that require elaborate powder diffraction and electron microscopy methods for structure determination.…”

“…[11] Furthermore,t he zeolitic Ba 3 P 5 N 10 Br:Eu 2+ is ap romising luminescent material for solid-state lighting that emits natural white light. [13][14][15][16][17] However,t he structural elucidation can be laborious owing to microcrystalline products that require elaborate powder diffraction and electron microscopy methods for structure determination. [13][14][15][16][17] However,t he structural elucidation can be laborious owing to microcrystalline products that require elaborate powder diffraction and electron microscopy methods for structure determination.…”

“…[12] However,t he accessibility of nitridophosphates through conventional solid-state synthesis is limited by the thermal stability of common starting materials like P 3 N 5 ,which tend to decompose below the crystallization temperature of the targeted phases.High-pressure synthesis using the multianvil technique has promoted the exploration of alkaline earth nitridophosphates like MP 2 N 4 (M = Be,Ca, Sr, Ba) and highpressure polymorphs of the silica analogous PON. [14,16] Synthetic success with alkali-metal and alkaline-earthmetal nitridophosphates could not yet be expanded to trivalent rare earth metals.I no rder to tackle the aforementioned problems,w et ailored an ew synthetic pathway by means of high-pressure metathesis and targeted rare-earthmetal nitridophosphates as am odel system. [14,16] Synthetic success with alkali-metal and alkaline-earthmetal nitridophosphates could not yet be expanded to trivalent rare earth metals.I no rder to tackle the aforementioned problems,w et ailored an ew synthetic pathway by means of high-pressure metathesis and targeted rare-earthmetal nitridophosphates as am odel system.…”