Sr3P6O6N8—a highly condensed layered phosphate

Abstract

We describe the synthesis and the structure elucidation of Sr 3 P 6 O 6 N 8 , a novel, highly condensed layered phosphate.During the last decades, inorganic phosphates have emerged from chemical commodities to advanced materials. Classical application areas of these basic inorganic compounds include usage as water softeners, fertilizers and coating materials.1 Nowadays, phosphates are being used as ionic conductors, 2 catalysts in organic syntheses 3 and even as modern optical materials. The structural chemistry of inorganic phosphates has been widely studied in the past.7 Classical representatives consist predominantly of orthophosphates, finite and infinite chainphosphates, as well as ring-phosphates. Here Q 0 (non-linking) up to Q 2 -type (double linking) PO 4 -tetrahedra occur. Band-, layer-or framework-structures with Q 3 or even Q 4 -type tetrahedra (comparable to silicates) have barely been identified. For higher condensed phosphates (exhibiting a degree of condensation (i.e. the molar ratio P : O = k > 1/3)), only a few examples in the group of ultraphosphates have been described. Moreover, the maximum degree of condensation for oxophosphates is k = 0.40. 8A further increase of cross-linking in phosphates, and thereby higher condensed structures, can be achieved in nitridophosphates or oxonitridophosphates by full or partial substitution O/N. With the integration of three-fold linking nitrogen, the structural diversity is significantly enhanced resulting in silicateanalogous networks, the latter being a consequence of the isolobal relation between P-N and Si-O which is further corroborated, for example, by HPN 2 (= PN(NH)) and PON that are isosteric to SiO 2 . By variation of the molar ratio O : N, thus changing the framework charge, network structures with different topologies similar to silicate structures can be achieved. Complete substitution of O for N, yields nitridophosphates like MP 4 N 7 with M = K, Rb, Cs 9 which adopt a network of corner-sharing PN 4 -tetrahedra. The silicate analogy has further been demonstrated by the class of nitridosodalites 10 and related oxonitridosodalites. 11However, complementing the diverse and rich structural chemistry of oxosilicates, new framework-types have been realized in (oxo-)nitridophosphates, 12 e.g. the first nitridic zeolite NPO. 13Department of Chemistry and Biochemistry, Ludwig-MaximiliansUniversität, Butenandtstrasse 5-13, 81377, Munich, Germany. E-mail: wolfgang.schnick@uni-muenchen.de; Fax: +49 89 Recently, this novel framework-type containing large 12-ring channels was paralleled by its nitridosilicate analogue.14 Another novel porous compound was obtained under high-pressure conditions-P 4 N 4 (NH) 4 (NH 3 )15 -the first nitridic clathrate that traps ammonia molecules in an unique cage structure that had been previously predicted as a possible silica framework.16,17 Highly condensed layer structures had not been realized so far; this includes oxophosphates and nitridophosphates, although the layered O¢-form of (P 2 O 5 ) x was discovered in the ...

Material Properties and Structural Characterization of M3Si6O12N2:Eu2+ (M=Ba, Sr)—A Comprehensive Study on a Promising Green Phosphor for pc‐LEDs

“…They are situated between the silicate layers and are six-or sevenfold coordinated by (O,N) atoms, respectively (see Figure 3). The crystal structure of Ba 3 Si 6 O 12 N 2 , which is isotypic with recently discovered Sr 3 P 6 O 6 N 8 , [47] can be derived from the structure of b-Si 3 N 4 .…”

Li14(PON3)2O – A Non‐Condensed Oxonitridophosphate Oxide

“…Many of the well-studied structures of SiO 2 have also been found in PON, such as the cristobalite, [8] quartz, [9] and coesite structure types. [10] Structures comparable to layer and chain silicates are found in Sr 2 P 6 O 6 N 8 [11] and M 2 PN 3 (M = Ca, Mg, Zn). [12,13] The high structural flexibility of (oxo)nitridophosphates may partly be caused by the fact that more than two tetrahedra can be linked by the nitride ion.…”

Crystal structure of barium oxonitridophosphate, Ba3P6O6N8

“…Ba 3 [2,3]. Just shortly before, the structure type of thissilicate compound, however, was elucidated for the oxonitridophosphate Sr 3 P 6 O 6 N 8 [4].Itexhibits ahighly condensed layered structure. Sr 3 P 6 O 6 N 8 wass uccessfullys ynthesized by transfering thes o-called azide high-pressure synthesisroute to the P/O/N system.This synthesis route was originally applied for the preparation of nitridophosphates in combination with P 3 N 5 [5,6].…”