Artigo
Structural features of phosphate and sulfate modified zirconia prepared by sol-gel route
Fecha
2004-10-01Registro en:
Journal of Sol-gel Science and Technology. Dordrecht: Springer, v. 32, n. 1-3, p. 91-97, 2004.
0928-0707
10.1007/s10971-004-5771-y
WOS:000228103300016
9971202585286967
5584298681870865
0000-0002-8356-8093
Autor
Universidade Estadual Paulista (Unesp)
Univ Paris 11
Resumen
This paper describes the effect of sulfate, phosphate and nitrate complexing ligands on the structural features of amorphous xerogels and on the crystallization of metastable zirconia phases during the xerogel-ceramic conversion. Powdered samples were prepared by a sol-gel route using zirconyl chloride precursors chemically modified by complexing ligands. The structural evolution of ZrO2 phases as function of firing temperature was analyzed by XRPD, EXAFS and P-13 NMR/MAS. The experimental results show the formation of metastable t-ZrO2 during the low firing temperature of xerogels modified by sulfate or phosphate groups. The martensitic tetragonal-monoclinic transformation occurs during desorption of sulfate groups. The largest temperature interval of stability of metastable tetragonal zirconia was observed for phosphate-modified xerogels.