(Magic Dopant) Amphoteric Behavior of a Redox-Active Transition Metal Ion in a Perovskite Lattice: New Insights on the Lattice Site Occupation of Manganese in SrTiO3

Published: October 05, 2016

Author(s)

Russell A. Maier, Matthew P. Donohue

Abstract

It is definitively shown for the first time that a transition metal, redox-active ion can exhibit amphoteric substitution in the SrTiO3 perovskite lattice. The manganese dopant is preferably accommodated as Mn2+ on the strontium site and as Mn4+ on the titanium site. Previous studies have suggested either type of substitution is possible for compositions with ideal Sr/Ti stoichiometry. However, it is shown, using Electron Paramagnetic Resonance (EPR), that manganese ions prefer amphoteric substitution for stoichiometric Sr/Ti cation ratios. The tuned Sr/Ti ratio can be used to manipulate the nature of the manganese substitution, and it is shown that large Sr/Ti ratios result in purely B-site doping. For B-site substituted manganese ions, a new EPR signal for Mn2+ on the B-site is discovered in reduced compositions. Amphoteric doping is usually only considered for large, rare-earth ions that have limited numbers of preferred valence states compared to transition metal ions. With improved control over the site of substitution and valence state, amphoteric doping of a transition metal redox- active ion offers the possibility to build new electronic functionality into the perovskite lattice.
Citation: Advanced Functional Materials
Pub Type: Journals

Keywords

Perovskite, Point Defect, Amphoteric, Oxygen Vacancy, EPR
Created October 05, 2016, Updated November 10, 2018