In situ phase analysis of the thermal decomposition products of zirconium salts

Štefančić, Goran and Gržeta, Biserka and Popović, Stanko and Musić, Svetozar (1999) In situ phase analysis of the thermal decomposition products of zirconium salts. Croatica Chemica Acta, 72 (2-3). pp. 395-412. ISSN 0011-1643

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Abstract

X-ray powder diffraction at high temperature was used to determinethe phase composition of the thermal decomposition productsof two zirconium salts, Zr(SO4)2 4 H2O and ZrO(NO3)2 2 H2O,and of a mixture of zirconium nitrates having Zr(OH)2(NO3)2 4.7H2O and ZrO(NO3)2 2 H2O as dominant components. Heating ofthe samples up to 1200 °C was performed inside a high-temperaturechamber, attached to a diffractometer, at an air pressure of2 10–3 Pa. Regardless of the structural differences in the startingsalts, thermal decomposition products crystallized to t-ZrO2,which remained stable up to 1200 °C. This result indicated thatthe structural nature of the starting materials was not the mostimportant factor of metastable t-ZrO2 formation. The thermodynamicallystable m-ZrO2 appeared after the cooling of the samples toroom temperature. If the cooling was performed at low air pressure,the m-ZrO2 content was small. Introduction of air, even atRT, caused a considerable increase of m-ZrO2, which became thedominant phase in all cases. The important role of oxygen in thet-ZrO2 m-ZrO2 transition indicates that the lack of oxygen in thezirconia lattice favours the formation of metastable t-ZrO2.

Item Type: Article
Keywords: t-ZrO2, m-ZrO2, X-ray diffraction, in situ phase analysis, phase transitions, lattice defects
Date: 1999
Subjects: NATURAL SCIENCES > Physics
Divisions: Faculty of Science > Department of Physics
Publisher: Hrvatsko kemijsko društvo
Depositing User: Gordana Stubičan Ladešić
Date Deposited: 25 Apr 2014 08:25
Last Modified: 25 Apr 2014 11:06
URI: http://digre.pmf.unizg.hr/id/eprint/964

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