Why literature shows La being substituted in place of a divalent instead of a trivalent metal atom in hexa-ferrite?

Valency of La is +3 , so it should be replacing iron in hexaferrite such that MFe12-xLaxO19.But the literature shows that it is replacing divalent atom such that the generic formula comes out to...

22 April 2020 4,901 5 View