B. Mottet, M. Pichavant, J. Bény
Sep 1, 1992
Citations
0
Influential Citations
30
Citations
Journal
Journal of the American Ceramic Society
Abstract
This paper reports that monoclinic zirconia has been synthesized hydrothermally from zirconium oxychloride in the range 20--100 MPa, 250--650[degrees]C, for run duration from 20 to 100 h and in the presence of NaOH, Na[sub 2]CO[sub 3], Na[sub 2]SO[sub 4], NH[sub 4]F, HNO[sub 3], and H[sub 2]SO[sub 4] additives. Isometric, platelike, and elongated crystal morphologies were obtained depending on the additive. Both spherulitic and isolated textures were encountered with H[sub 2]SO[sub 4]. Growth of isometric crystals follows a general dissolution--precipitation mechanism. For H[sub 2]SO[sub 4], two growth steps were identified: an early spherulitic step followed by an isolated crystals step resulting from Ostwald ripening of preexisting spherulites. The formation of spherulites is consistent with the specific properties of the sulfuric hydrothermal medium.