Localized to Itinerant Electronic Transitions in Transition-Metal Oxides with the Perovskite Structure

The transition from localized to itinerant electronic behavior is shown to be first-order. In a perovskite, segregation into localized-electron and itinerant-electron phases can be accomplished by cooperative atomic displacements. Sr 1 - x Ca x VO 3 and La 1 - x Nd x CuO 3 illustrate single-valent perovskites that exhibit localized-electron fluctuations in an itinerant-electron matrix on approaching the Mott−Hubbard transition, and CaFeO 3 and NdNiO 3 form charge-density waves with MO complexes or itinerant-electron slabs alternating with localized-electron states.