Abstract: A part includes a substrate, having, adjacent to a surface of the substrate, at least a portion that is made from a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including at least a first layer including a rare earth disilicate of formula REa2Si2O7 present at a molar content lying in the range 70% to 99.9%, where REa is a rare earth element; and at least one rare earth oxide of formula REb2O3 present at a molar content lying in the range 0.1% to 30%, where REb is a rare earth element different from REa.

Abstract: A part includes a substrate having, adjacent to a surface of the substrate, at least a portion that is made of a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including a first layer including at least one first rare earth silicate and presenting grains with a mean size less than or equal to 1 ?m; and a second layer covering the first layer, the second layer including at least one rare earth silicate and presenting grains with a mean size greater than 1 ?m.

Abstract: A part includes a substrate having, adjacent to a surface of the substrate, at least a portion that is made of a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including a first layer including at least one first rare earth silicate and presenting grains with a mean size less than or equal to 1 ?m; and a second layer covering the first layer, the second layer including at least one rare earth silicate and presenting grains with a mean size greater than 1 ?m.

Abstract: A part includes a substrate, having, adjacent to a surface of the substrate, at least a portion that is made from a material that contains silicon, and an environmental barrier formed on the surface of the substrate, the environmental barrier including at least a first layer including a rare earth disilicate of formula REa2Si2O7 present at a molar content lying in the range 70% to 99.9%, where REa is a rare earth element; and at least one rare earth oxide of formula REb2O3 present at a molar content lying in the range 0.1% to 30%, where REb is a rare earth element different from REa.

Abstract: A gas electrode includes a plurality of stacked layers (2, 3, 4), wherein the first layer (2) is in contact with a solid substrate (1) while the last layer (4) has a free outer surface to be contacted with a gas, each layer being made of at least one mixed oxide selected from the group including perovskites and Ruddlesden-Popper phases, the micro-structure of the first layer (2) being different from that of the last layer (4), the porosity of the different layers (2, 3, 4) increasing from the first layer (2) towards the last layer (4), and the different layers stacked on each other defining a network of a solid interconnected material between the free outer surface of the last layer (4) and the solid substrate with a total thickness higher than 1 ?m. A method for making such an electrode and its use in an electrochemical cell are disclosed.

Abstract: The invention relates to an oxide material of general formula (I) A2?x?yA?XA?yM1?z M?Z04+?, wherein A and A? are independently a metal cation of a group formed by lanthanides and/or alkalis and/or alkaline earths, A? is a cationic gap, i.e. a cation vacancy A and/or A?, M and M? are independently a metal of a group formed by transition metals such as 0<y<0.30, preferably 0<y=0.20; 0<?<0.25, preferably 0<?<0.10; 0=x=1; and 0=z=1. An air electrode containing said material and an electric power producing device in the form of a fuel cell provided with at least one electrochemical cell comprising said electrode are also disclosed.

Abstract: The invention relates to a method for water electrolysis consisting in using an electrode containing at least one type of oxide material of general formula A2?x?yA?xA?yM1?zM?zO4+?, wherein A is a lanthanide and/or alkaline and/or alkaline earth metal cation, A? is at least one lanthanide and/or alkaline and/or alkaline earth metal cation, A? is a cation gap, M is a transition metal element, M? is at least one type of transition metal element, wherein said metal is such that 0<y<0.30, preferably 0<y?0.20; ?0 1??<0 25, preferably 0??<0.