In Situ Powder X-ray Diffraction, Synthesis, and Magnetic Properties of the Defect Zircon Structure ScVO4−x

• Published in: Inorganic chemistry Vol. 48; no. 22; pp. 10553 - 10559
• Main Authors: Shafi, Shahid P, Kotyk, Matthew W, Cranswick, Lachlan M. D, Michaelis, Vladimir K, Kroeker, Scott, Bieringer, Mario
• Format: Journal Article
• Language: English
• Published: American Chemical Society 16-11-2009
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic900927j

We report the formation pathway of ScVO4 zircon from ScVO3 bixbyite with emphasis on the synthesis and stability of the novel intermediate defect zircon phase ScVO4−x (0.0 < x ≤ 0.1). The formation pathway has been investigated by means of thermogravimetric/differential thermal analysis and in situ powder X-ray diffraction. The oxidation of ScVO3 to ScVO4 involves two intermediates of composition ScVO3.5+y (0.00 ≤ y ≤ 0.22) and the novel phase ScVO4−x . ScVO4−x crystallizes in the defect zircon structure in space group I41/amd (141) with a = 6.77761(5) Å and c = 6.14045(8) Å. Oxygen defect concentrations in bulk ScVO4−x samples range from 0.0 < x ≤ 0.1. ScVO4−x is compared with the fully oxidized zircon structure ScVO4 using powder X-ray diffraction, neutron diffraction, and bulk magnetic susceptibility data as well as 45Sc and 51V solid state NMR spectroscopy. ScVO4−x can only be obtained by oxidation of ScVO3 or ScVO3.5+y while the reduction of ScVO4 does not yield the novel defect structure. Mechanistic insights into the oxidative formation of ScVO4 via the defect structure are presented.