P4W8O32: a mixed-valence tunnel structure built up of ReO3-type slabs connected through PO4 tetrahedra

Abstract

ExperimentalThe crystal structure of P4WsO32 has been solved by three-dimensional single-crystal X-ray analysis. The refinements have been made in the space group P212121 with a = 5.285 (2), b = 6.569 (1), c = 17.351 (3)A, leading to R --0.058 and R w --0.071 for 967 independent reflections. The framework of this structure, built up of WO 6 octahedra and PO4 tetrahedra, can be described as ReOa-type slabs connected through PO 4 tetrahedra. This type of connection creates pentagonal tunnels in the [100] direction. Two sorts of empty cages are formed, limited by twelve or eighteen O atoms. The possibility of insertion of cations in the cavities of the structure and the existence of microphases P4W4nO 12n÷ 8 are discussed.

Crystallization and second harmonic generation in thermally poled niobium borophosphate glasses

“…The structure is isotypic with that of monophosphate tungsten bronze W 8 P 4 O 32 [24]. For SHG measurements, a single-phase powder of Na 4 Nb 8 P 4 O 32 was prepared by solid-state technique from NaPO 3 and Nb 2 O 5 at 860 1C.…”

Electronic structure analysis of quasi-one-dimensional monophosphate tungsten bronzes

“…The orthorhombic unit cell parameters are a ជ ϭ5.285 Å, b ជ ϭ6.569 Å, and c ជ ϭ17.351 Å, and the compound crystallizes in the P2 1 2 1 2 1 space symmetry group. 11 It is important to stress the existence of two kinds of W atoms sites, depending which corners of the WO 3 octahedra they share. Some WO 3 octahedra share O atoms only with other WO 3 octahedra, while a second kind share O atoms with PO 4 tetrahedra also.…”

Characterization of New Lead-Based Monophosphate Tungsten Bronzes, Pbx(PO2)4(WO3)2m(6≤m≤10)

“…The discovery of electronic instabilities leading to a charge density wave (CDW) state in the quasi-two-dimensional (2D) monophosphate tungsten bronzes (PO ) (WO ) K (1-5) has renewed the interest of these materials synthesized for the first time more than 15 years ago (6)(7)(8)(9).…”