A Niobium(V) Arsenate: Nb₉AsO₂₅

Abstract

Nonaniobium arsenic pentacosaoxide contains 3 × 3 ReO3-type NbO~, octahedral columns extended along c. Each column is linked to four crystallographically identical columns through shared edges of NbO6 octahedra and shared corners of AsO4 tetrahedra.

Nanostructured Magnetic Cuprate Cluster: Synthesis, Structure, UV−Vis Spectroscopy, and Magnetic Properties of a New Copper(II) Arsenate NaCuAsO4 Containing Discrete [Cu4O16]24- Clusters

“…The absorption above 3.2 eV can be assigned to the LMCT (ligand-to-metal charge transfer) bands originated from the AsO 4 oxy anion. These bands are comparable with the values acquired in earlier studies. , The ligand-field spectra show a rather intense absorption band centered around 1.3 eV corresponding to the otherwise Laporte-forbidden, d−d transition. The intense absorption is consistent with the much-distorted [4 + 1] and [4 + 2] coordination around the Cu 2+ cations.…”

β-Nb9VO25

“…For isotypic compouds, see: Ulutagay et al (1998); Roth et al (1965); Casais et al (1993). For physical properties, see: Prabaharan et al (1997); Aranda et al (1992); Bergner et al (2009).…”

“…La comparaison de notre structure avec celles des oxydes analogues, montre qu'elle est isotype à: Nb 9 PO 25 (Roth et al, 1965), Ta 9 VO 25 (Casais et al, 1993) et Nb 9 AsO 25 (Ulutagay et al, 1998). Le composé étudié Nb 9 VO 25 (forme β) cristallise dans le système quadratique, groupe d'espace centrosymétrique I4/m (87) alors que celui isoformulaire Nb 9 VO 25 (forme α) est non centrosymétrique, groupe d'espace I4 (82) (Casais et al, 1993).…”