ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract The title phases Ba2R2/3V2O8 (R = La, Nd) and Sr2La2/3V2O8, synthesised by solid state reaction of oxides at 1350°C, have structures derived from that of the palmierite-type of Ba3V2O8; the stoichiometry is often written as A3RV3O12. Ba2La2/3V2O8 is hexagonal, spacegroup R―3m, a = 5.75271(7), c = 21.0473(5) Å, Z = 3; cation ordering was determined by joint Rietveld refinement using X-ray and neutron powder diffraction data, R wp = 4.45%, R p = 6.33%, χ2 = 6.847. In the Ba3V2O8 structure, Ba occupies two sites: 3a and 6c. In Ba2La2/3V2O8, Ba wholly occupies the 3a site; the 6c site contains both Ba, La and vacancies. Bond valence analysis was inconclusive, but tends to support the presence of Ba on the 3a site. Sr2La2/3V2O8 and Ba2Nd2/3V2O8 are isostructural, as confirmed by Rietveld refinement using X-ray powder diffraction data. Ba2R2/3V2O8 phases could not be synthesised for lanthanides, R, smaller than Sm.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1004815120209
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