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

Autori
Štefanić, Goran ; Gržeta, Biserka ; Popović, Stanko ; Musić, Svetozar

Izvornik
Croatica chemica acta (0011-1643) 72 (1999), 2-3; 395-412

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Sažetak
X-ray powder diffraction at high temperature was used to determine the phase composition of the thermal decomposition products of 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. 4,7 H2O and ZrO(NO3)2.2 H2O as dominant components. Heating of the samples up to 1200 oC was performed inside a high-temperature chamber, attached to a diffractometer, at an air pressure of cca 2 x 10-3 Pa. Regardless of the structural differences in the starting salts, thermal decomposition products crystallized to t-ZrO2, which remained stable up to 1200 oC. This result indicated that the structural nature of the starting materials was not the most important factor of metastable t-ZrO2 formation. The thermodynamically stable m-ZrO2 appeared after the cooling of the samples to room temperature. If the cooling was performed at low air pressure, the m-ZrO2 content was small. Introduction of air, even at RT, caused a considerable increase of m-ZrO2, which became the dominant phase in all cases. The important role of oxygen in the t-ZrO2 - m-ZrO2 transition indicates that the lack of oxygen in the zirconia lattice favours the formation of metastable t-ZrO2.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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