Preparation and Properties of Substituted Iron Tungstates.
Abstract
FeWO6 is an n-type semiconductor crystallizing with the tri-alpha-PbO2 structure, an ordered variant of the more basic alpha -PbO2 structure. The extrinsic semiconducting behavior is consistent with the presence of both iron(II) and iron(III) in the puckered chains of the structure. The presence of the two valence states of iron is due to a solid solution of a small amount of FeWO4 in Fe2WO6. Substitution of chromium(III) into Fe2WO6 changes the structure type to inverse trirutile, and it is found that chromium(III) effectively blocks any electron hopping between iron(II) and iron(III) in this structure. FeWO4, on the other hand, is a p-type semiconductor crystallizing with the wolframite structure. The extrinsic semiconducting behavior of FeWO4 is consistent with the presence of both iron(II) and iron(III) in the puckered chains produced by solid solution with a small amount of FeWO6. Substitution of manganese(II) into FeWO4 mainitains the wolframite structure; however, the room temperature resistivity does not vary as markedly as anticipated for electron hopping between iron(II) and iron(III) along the puckered chains. This suggests that contributions to the electrical conductivity may occur by interchain electron transfer via (WO6) octahedra in the FeWO4 structure.
Document Details
- Document Type
- Technical Report
- Publication Date
- Nov 17, 1982
- Accession Number
- ADA121699
Entities
People
- H. Leiva
- K. Kourtakis
- K. Sieber
- Kirby Dwight
- Robert N. Kershaw
Organizations
- Brown University