  Cation disorder is an important design criterion for technologically relevant
transition-metal (TM) oxides, such as radiation-tolerant ceramics and Li-ion
battery electrodes. In this letter, we use a combination of first-principles
calculations, normal mode analysis, and band-structure arguments to pinpoint a
specific electronic-structure effect that influences the stability of
disordered phases. We find that the electronic configuration of a TM ion
determines to which extent the structural energy is affected by site
distortions. This mechanism explains the stability of disordered phases with
large ionic radius differences and provides a concrete guideline for the
discovery of novel disordered compositions.
