| abstract |
Process for producing a powder of zirconium oxide and / or hafnium oxide particles, doped or not, comprising a calcination step (e)) or of hydrothermal treatment (e)) of a starting particle powder a material selected from zirconium and / or hafnium derivatives of formula M (OH) (N ') (OH), M being Zr, Hf, or a mixture of Zr and Hf, N'being an anion or a mixture of anions, the indices x and y being strictly positive numbers. z being a positive or zero number, said material having a solubility in water at a temperature below 20 ° C of less than 10 mol / l, said derivative being dopable or non-dopable, zirconium hydrates and / or hafnium of formula MO (OH) (OH), M being Zr, Hf, or a mixture of Zr and Hf, the indices x and z being positive or zero numbers, the index y being a positive number, and 2x + y being equal to 4, doped or not, or a mixture of such hydrates, doped or not, and - their mixtures, or a mixture of these particles, and when said starting particles are in a hydrate, said powder having a porosity index Ip greater than 2, the porosity index being equal to the ratio A / A where - A is the theoretical geometric specific area of the particles of the powder; A is the measurement of the actual specific area by BET, and said starting particles consist of aggregated or unaggregated base particles having a sphericity index of less than 0.6. |