Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10632196 | Materials Research Bulletin | 2005 | 10 Pages |
Abstract
Negative thermal expansion material, Y2W3O12 has been synthesized by the solid-state method and bulk thermal expansion of the material has been investigated from 300 to 1100 K. The material reversibly forms a trihydrate composition whose X-ray diffraction pattern can be indexed to an orthorhombic unit cell with a = 10.098(1) Ã
, b = 13.315(3) Ã
, c = 9.691(4) Ã
. The cell volume of the hydrated pattern is 7% smaller than the unhydrated cell volume. According to the dilatometric studies, the material shows a 3-6% increase in the linear strain at about 400 K, which can be attributed to the removal of water. Sintering the material at 1473 K leads to large grain size of >100 μm, which results in a large hysteresis in the bulk thermal expansion behavior. Hot pressing at 1273 K under a uniaxial pressure of 25 MPa results in a fine-grained (2-5 μm) ceramic. Glazing the ceramic prevents moisture pick up and a linear thermal expansion over the entire temperature range 1100-300 K and an average linear thermal expansion co-efficient of â9.65 Ã 10â6/K is observed. The effect of water on the thermal expansion behavior of this system is discussed.
Related Topics
Physical Sciences and Engineering
Materials Science
Ceramics and Composites
Authors
S. Sumithra, A.M. Umarji,