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

Štefanić, Goran; Gržeta, Biserka; Popović, Stanko; 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 determine the phase composition of the thermal decomposition products of two zirconium salts, Zr(SO4)(2). 4H(2)O 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). 2H(2)O as dominant components. Heating of the samples up to 1200 degrees C was performed inside a high-temperature chamber, attached to a diffractometer, at an air pressure of approximate to 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 degrees C. 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.

Item Type:	Article
Uncontrolled Keywords:	t-ZrO2; m-ZrO2; X-ray diffraction; in situ phase analysis; phase transitions; lattice defects; low-temperature t-zro2; x-ray-diffraction; tetragonal zro2; crystal phases; crystallization; transformation; powder; stabilization; scattering; stability
Subjects:	NATURAL SCIENCES > Chemistry
Divisions:	Division of Materials Chemistry Division of Materials Physics
Projects:	Project title Project leader Project code Project type Sinteza i mikrostruktura metalnih oksida i oksidnih stakala Svetozar Musić 00980903 MZOS
Depositing User:	Goran Štefanić
Date Deposited:	25 Nov 2013 15:05
URI:	http://fulir.irb.hr/id/eprint/1120

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