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The phase development of the amorphous precursors of the ZrO2-SnO2 system during the thermal treatment

Goran Štefanić ,  Svetozar Musić ,  Mile Ivanda 

Ruđer Bošković Institute, Bijenička 54, Zagreb 10000, Croatia

Abstract

The amorphous precursors of the ZrO2-SnO2 system on the ZrO2-rich side of the concentration range were prepared by co-precipitation from aqueous solutions of the corresponding salts. The Zr/Sn molar ratio in the obtained products was determined by the results of energy-dispersive X-ray spectrometry (EDS). The thermal behaviour of the amorphous precursors was monitored using differential thermal analysis (DTA), X-ray powder diffraction (XRD), Raman spectroscopy and field emission scanning electron microscopy (FE-SEM). Crystallization temperature of the amorphous precursors rose with an increase in the SnO2 content, from 405 °C (0 mol% SnO2) to 500 °C (40 mol% SnO2). The results of phase analysis show that the incorporation of Sn4+ ions has very small influence on the stabilization of high-temperature polymorphs of ZrO2. A phase structurally closely related to monoclinic (m-) ZrO2 is dominant in all crystallization products. Metastable products obtained upon crystallization of amorphous precursors also contain a phase structurally closely related to tetragonal (t-) ZrO2, which disappears with further thermal treatment (up to 1100 °C). The first sign of a phase structurally closely related to cassiterite (t-SnO2) appeared in the crystallization products with 30 mol% of SnO2. A rise in calcination temperature leads to a decrease in the solid solubility of Sn4+ ions. The results of precise lattice parameter measurements show that the incorporation of Sn4+ ions causes an asymmetric local distortion of the m-ZrO2-type crystal lattice.

 

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Presentation: Oral at E-MRS Fall Meeting 2007, Symposium F, by Goran Štefanić
See On-line Journal of E-MRS Fall Meeting 2007

Submitted: 2007-05-14 12:10
Revised:   2009-06-07 00:44