Production of self-supporting ceramic materials having a reduced thickness and containing metal oxides

1. Method for manufacturing a metal-oxide-based ceramic solid electrolyte, comprising the following steps:

(a) inserting, into a flash sintering device, a nanocrystalline powder comprising crystallites and crystallite agglomerates of a ceramic of formula:

Zr 1-x M x O 2 , where M is chosen from yttrium, scandium and cerium, or

Ce 1-x M′ x O 2 , where M′ is chosen from gadolinium, scandium, samarium and yttrium, where x lies between 0 and 0.2,

said powder having:

an average crystallite size, measured by X-ray diffraction, of between 5 and 50 nm (nanometers),

an average crystallite agglomerate size, measured using a scanning electron microscope (SEM), of between 0.5 and 20 μm (microns),

a specific surface area, measured using the BET method, of between 20 and 100 m 2 /g; and

(b) flash sintering said powder by applying a pressure of between 50 and 150 MPa, at a temperature of between 850° C. and 1400° C., for a period between 5 and 30 minutes.

2. The method according to claim 1 , wherein step (a) comprises inserting a plurality of layers of nanocrystalline powder into said flash sintering device, the various layers being separated from one another by a respective separating sheet capable of withstanding the thermal and mechanical conditions of the sintering step (b), so as to obtain, after the sintering step (b), a multilayer of a number of ceramic wafers and separating sheets arranged in alternation.

3. The method according to claim 2 , further comprising a step (c) of thermally and/or chemically treating the multilayer obtained after the sintering step (b), step (c) being used to selectively remover-the separating sheets.

4. The method according to claim 2 , wherein the separating sheets are graphite sheets and in that step (c) comprises treating the sintered multilayer in air at a temperature of between 700 and 900° C.

5. The method according to claim 1 , further comprising a step of synthesizing said powder using a sol-gel technique before inserting step (a).

6. The method according to claim 5 , wherein the nanocrystalline powder is synthesized from an acidic aqueous solution of zirconium salts, optionally mixed with a yttrium, scandium or cerium salt, or from an acidic aqueous solution of cerium salts, optionally mixed with a gadolinium, scandium, samarium or yttrium salt, said solution further containing hexamethylenetetramine (HMTA) and acetylacetone (ACAC).

7. The method according to claim 5 , wherein the nanocrystalline powder is synthesized by the sol-gel route from a tetraalkoxyzirconium compound and an yttrium salt in the presence of a chelating agent.

8. The method according to claim 1 , wherein the temperature of step (b) lies between 1000° C. and 1300° C.

9. The method according to claim 1 , wherein the pressure applied in step (b) lies between 80 and 120 MPa.

10. The method according to claim 1 , wherein the duration of step (b) lies between 10 and 30 minutes.

11. A metal-oxide-based ceramic that can be obtained by the method according to claim 1 .

12. A ceramic according to claim 11 , wherein it is a wafer having a thickness of 200 μm or less and an area of between 1 and 100 cm 2 .

13. A ceramic according to claim 11 , wherein it has a porosity of between 4% and 1%.

14. A fuel cell comprising a ceramic according to claim 13 as a solid electrolyte.

15. A high-temperature electrolysis cell comprising a ceramic according to claim 13 as a solid electrolyte.

16. A measurement and/or detection device comprising a ceramic according to claim 13 as an electrochemical sensor.

17. A ceramic according to claim 11 , wherein it has a porosity greater than 4% and ranging up to 30%.

18. A method of filtration wherein the filtration membrane is a ceramic according to claim 17 .