05-04-2018 дата публикации
Номер: US20180093229A1
A method and a composition to stabilize the surface cation chemistry of the perovskite or related oxides, and thus, to minimize or completely avoid the detrimental segregation and phase separation of dopant cations at the surface can include modifying the surface with more oxidizable metal cations and/or more oxidizable metal oxides, thereby reducing the oxygen vacancy concentration at the very surface. 1. A composition comprising: [{'br': None, 'sub': x', '1-x', 'y', '1-y', '3±δ, 'AA′BB′O\u2003\u2003(I)'}, {'br': None, 'sub': x', '1-x', '2', 'y', '1-y', '2', '5, '(AA′)(BB′)O\u2003\u2003(II)'}, {'br': None, 'sub': x', '1-x', 'n+1', 'y', '1-y', 'n', '3n+1, '(AA′)(BB′)O\u2003\u2003(III)'}, 'wherein each of A and A′, independently, is a rare earth metal or an alkaline earth metal, x is in the range of 0 to 1, each of B and B′, independently, is a transition metal, y is in the range of 0 to 1, δ is in the range of 0 to 1, and n is a number of layers; and, 'a base layer including a material of formula (I), (II) or (III), wherein the formula (I), (II) and (III) area surface layer including a metal, a metal cation or an oxide of one or more metal elements, or a combination thereof.2. The composition of claim 1 , wherein the cation and the oxide of one or more metal element are more oxidizable claim 1 , or more difficult to reduce claim 1 , than the material of the formula (I claim 1 , II claim 1 , or III).3. The composition of claim 1 , wherein the material includes a perovskite oxide or a perovskite-related oxide claim 1 , including a brownmillerite or a Ruddlesden Popper.4. The composition of claim 1 , wherein the rare earth metal includes Sc claim 1 , Y claim 1 , La claim 1 , Ce claim 1 , Pr claim 1 , Nd claim 1 , Pm claim 1 , Sm claim 1 , Eu claim 1 , Gd claim 1 , Tb claim 1 , Dy claim 1 , Ho claim 1 , Er claim 1 , Tm claim 1 , Yb or Lu.5. The composition of claim 1 , wherein the alkaline earth metal includes Be claim 1 , Mg claim 1 , Ca claim 1 , Sr claim 1 , Ba or Ra ...
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