Hexagonal Perovskite-Type Phases in the BaO-Rich Part of the BaO–WO3–Nb2O5 System

$48.00 plus tax (Refund Policy)

Download / Buy Article:


BaO-rich phases with the nominal compositions Ba6NbxW3−xO15−x/2 (x=1, 2), 9L-Ba9Nb2W4O26, 12-layered (12L)-Ba4Nb2WO12, and 27L-Ba9Nb6WO27 were synthesized as polycrystalline powders using solid-state techniques and characterized by X-ray powder diffractometry and transmission electron microscopy. Of these powders only the 5L2-Ba6NbxW3−xO15−x/2 (x=2) and 9L-Ba9Nb2W4O26 were obtained as single-phase materials. The formation of Ba6NbxW3−xO15−x/2 (x=1, 2) started with the occurrence of binary compounds. Thus, 5L1-Ba6NbxW3−xO15−x/2 (x=1) appeared over binary Ba4Nb2O9 in contrast to 5L2-Ba6NbxW3−xO15−x/2 (x=2), which formed through a reaction between Ba5Nb4O15 and other barium–tungsten oxides. 5L2-Ba6NbxW3−xO15−x/2 (x=2) appeared in two different polymorphs structurally related to the hexagonal Ba6Ta2WO14 and the orthorhombic -Ba4Nb2O9. The structural refinement of the high-temperature 5L2-Ba6NbxW3−xO15−x/2 (x=2) was carried out using the space group P3m1. The fitted parameters of the hexagonal unit cell corresponded to aH=6.030(1) Å and cH=12.44(1) Å. Additional reflections of variable intensity and strong, diffuse scattering in the electron diffraction patterns indicated a strong structural disorder. The formation of 9L-Ba9Nb2W4O26, 12L-Ba4Nb2WO12, and 27L-Ba9Nb6WO27 started with the reaction between the binary compounds and continued over a series of intermediate hexagonal perovskite-type phases lying on the Ba3W2O9–Ba5Nb4O15 tie line.

Document Type: Research Article

DOI: http://dx.doi.org/10.1111/j.1551-2916.2009.03299.x

Affiliations: 1: Advanced Materials Department, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia 2: Laboratoire CRISMAT, 6 Boulevard Marechal Juin, 14050 Caen Cedex 4, UMR6508, France 3: Department for Nanostructured Materials, Jožef Stefan Institute, SI-1000 Ljubljana, Slovenia

Publication date: December 1, 2009

Related content



Share Content

Access Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content
Cookie Policy
Cookie Policy
ingentaconnect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more