PREPARATION OF STABILIZED HAFNIUM OXIDE P OWDERS FROM OXALIC PRECURSORS

This paper deals with the preparation of an oxalic precursor from hafn ium tetrachloride. The heat treatment of this complex allows to obtain hafnium oxide at lower temperatures. The stabilization of HfO2 in the cubic form by yttrium oxide has been studied. The introduction of ytt rium in the precursor is obtained by a reaction between oxalic hafnyl acid and yttrium carbonate. The heat treatment of the yttrium complex has been investigated by DTA-TGA, infrared spectroscopy and X-ray diff raction at various temperatures. The apparition of the HfO2-Y2O3 solid solution is detected by X-ray diffraction at temperatures as low as 5 00-degrees-C.