Coexistence of Rutile and Trirutile Phases in a Natural Tapiolite Sample

✍ Scribed by E.J. Kinast; L.I. Zawislak; J.B.M. da Cunha; V. Antonietti; M.A.Z. de Vasconcellos; C.A. dos Santos

• Publisher: Elsevier Science
• Year: 2002
• Tongue: English
• Weight: 523 KB
• Volume: 163
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.2001.9395

✦ Synopsis

We report X-ray powder di4raction (XRD), electron probe microanalysis (EPMA), and MoK ssbauer spectroscopy (MS) measurements performed on a natural tapiolite with composition Fe 0.57 Mn 0.37 Ti 0.10 Ta 1.27 Nb 0.67 O 6 . XRD and MS suggest that besides being partially ordered the as-collected sample is a mixture of trirutile (P4 2 /mnm, a ‫؍‬ 4.7532(9) A s , c ‫؍‬ 9.228(7) A s ) and Nb-rich rutile (P4 2 /mnm, a ‫؍‬ 4.856(2) A s , c ‫؍‬ 3.098(1) A s ) structures. The MoK ssbauer spectra of the rutile (Fe, Mn, Ta, Nb)O 2 were 5tted to ‫50.0؎27.1؍‬ mm/s and ‫؍‬ 1.10؎0.03 mm/s at 300 K and to ‫60.0؎01.2؍‬ mm/s and ‫؍‬ 1.18؎0.03 mm/s at 80 K. The present results suggest that cation ordering in compounds of the tapiolite series can be easily assessed by MoK ssbauer spectroscopy in a way similar to that as previously demonstrated for the columbite series.