Borophosphates—A Neglected Class of Compounds: Crystal Structures of M^II[BPO₅] (M^II  Ca, Sr) and Ba₃[BP₃O₁₂]

Abstract

Vertex‐sharing BO4 and PO4 tetrahedra form the framework of the title compounds. Ca[BPO5] and Sr[BPO5] crystallize in the stillwellite structural type and contain tetrahedral chain anions [BPO], which can be described as loop‐branched “dreier” single chains. In Ba3[BP3O12] the tetrahedral anions form “zweifach” open “vierer” single chains. Given these results and the known linking modes of tetrahedral units, it is expected that borophosphates with layered and framework structures, as well as microporous structures, can be found.

Novel Fundamental Building Blocks and Site Dependent Isomorphism in the First Actinide Borophosphates

“…9 While the first study of borophosphate was conducted almost 150 years ago, 10 systematic research on crystalline borophosphates has been performed during the past 18 years. 11 Since then, hundreds of borophosphate compounds have been reported and reviewed. 1,11 Besides crystals, borophosphate glasses have found high interest owing to their various real or potential technological applications, such as their use as bone transplantates, 12 solidstate lasers, 13 sealant, 14 even nonlinear optical devices if suitably poled, 15 and matrix for nuclear waste vitrification.…”

“…11 Since then, hundreds of borophosphate compounds have been reported and reviewed. 1,11 Besides crystals, borophosphate glasses have found high interest owing to their various real or potential technological applications, such as their use as bone transplantates, 12 solidstate lasers, 13 sealant, 14 even nonlinear optical devices if suitably poled, 15 and matrix for nuclear waste vitrification. 16 The last point has generated some concern since during long-term storage and under certain circumstances nuclear waste glasses might undergo corrosion with subsequent formation of numerous crystalline products and possible degradation of the mechanical integrity of the glass.…”

NH4[BAsO4F] – a New Layer Fluoro‐boroarsenate with a Silicate Related Topology

“…LiBF 4 (0.469 g / 5 mmol, Sigma Aldrich, 98%), NH 4 H 2 AsO 4 (1.192 g / 7.5 mmol, ABCR, 98%) and B(OH) 3 (0.460 g / 7.5 mmol, Sigma Aldrich, 99+%) were thoroughly mixed with a pestle and mortar in a molar ratio of 2:3:3. The dry mixture was transferred into a 23 ml Parr autoclave and treated at 240 °C for 14 days.…”

“…Borate groups in a 1:1 combination with group 15 oxotetrahedra, such as PO 4 , produce building-blocks isoelectronic with silicates and lead to analogous structures, such as the quartz heterotype BPO 4 [2], chain structures and three-dimensional frameworks [3,4]. This compositional equivalence also holds for the combination of borate groups with arsenate groups, where detailed investigations have only recently started [5].…”

Determination of the Hydrogen Positions in the Novel Barium Boroarsenate Ba[B2As2O8(OH)2] by Combined Single Crystal X‐ray and Powder Neutron Investigations

“…This demonstrates further the structural versatility of boroarsenate compounds formed from linked tetrahedra. 3 was used as a starting material and the products were not washed with hot water in order to avoid mechanical damage, which hampers the manual separation of the product phases. This led to a noticeable contamination of the sample with NH 4 Br.…”