7. The method of claim 3, wherein, before adding of the hydroxide of the doped material M′, a pH of the solution comprising the metal precursor is adjusted to a range of 10 to 12, and after adding of the hydroxide of the doped material M′, the pH is gradually adjusted to a range of 9 to 10 during co-deposition.
the solution
pH
a range of 10 to 12
the solution
pH
a range of 9 to 10