Paper Title:
Synthesis of ZrW2O8 Ceramics and Composites from Aqueous Sol-Gel Precursors
  Abstract

The thermal expansion of a ceramic material in general leads to a positive thermal expansion coefficient (α). In the last decennium, several families of materials which exhibit negative thermal expansion, arising from a specific geometrical effect in their so-called open framework structures, have been discovered. Usually, this negative thermal expansion coefficient is small, anisotropic and the phenomena occur in a very small temperature interval. ZrW2O8 is an exception because of its large and isotropic negative thermal expansion coefficient (NTE) in a temperature range from 0.5K to 1050K. A cubic symmetry is found over the entire stability range with a phase transition from α-ZrW2O8 to β-ZrW2O8 near 430K. This phase transition is noticed by a change in α. The aqueous citrate-gel method is a suitable synthesis route for negative thermal expansion ceramics and will give a fine, pure and homogenous oxide mixture, well suitable for the preparation of ZrW2O8. The expansion coefficient of α–ZrW2O8 is -11 μm/m K whereas for the β- ZrW2O8 a value of -3 is obtained.

  Info
Periodical
Edited by
P. VINCENZINI
Pages
218-222
DOI
10.4028/www.scientific.net/AST.45.218
Citation
K. de Buysser, S. Hoste, I. Van Driessche, "Synthesis of ZrW2O8 Ceramics and Composites from Aqueous Sol-Gel Precursors", Advances in Science and Technology, Vol. 45, pp. 218-222, 2006
Online since
October 2006
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