Abstract: The invention relates to a method for optimizing the conductivity provided by the displacement of H+ protons and/or OH? ions in a conductive membrane made of a material permitting the insertion of steam into said membrane, wherein said method comprises the step of inserting under pressure gaseous flow containing the steam into said membrane in order to force said steam into said membrane under a certain partial pressure so as to obtained the desired conductivity at a given temperature, said partial pressure being higher than or equal to 1 bar, a drop in the operational temperature being compensated by an increase in said partial pressure in order to obtain the same desired conductivity. The invention can be used in particularly interesting applications in the fields of high-temperature water electrolysis for producing hydrogen, of the manufacture of fuel cells using hydrogen fuel, and of hydrogen separation and purification.

Abstract: The present invention relates to a process for preparing mineral particles (p) from mineral species precursors, said process comprising a step (E) in which a fluid medium (F) containing said precursors in solution and/or dispersed in a solvent is injected into a reactor containing CO2 in the supercritical state by way of an injection nozzle opening into a zone where the supercritical CO2 is at a temperature greater than or equal to the temperature for conversion of the precursors into corresponding mineral species. The invention also relates to the particles (p) as obtained by the process, as well as uses thereof.

Abstract: The invention relates to a method for optimising the conductivity provided by the displacement of H+ protons and/or OH? ions in a conductive membrane made of a material permitting the insertion of steam into said membrane, wherein said method comprises the step of inserting under pressure gaseous flow containing the steam into said membrane in order to force said steam into said membrane under a certain partial pressure so as to obtained the desired conductivity at a given temperature, said partial pressure being higher than or equal to 1 bar, a drop in the operational temperature being compensated by an increase in said partial pressure in order to obtain the same desired conductivity. The invention can be used in particularly interesting applications in the fields of high-temperature water electrolysis for producing hydrogen, of the manufacture of fuel cells using hydrogen fuel, and of hydrogen separation and purification.