Stability and methodological feasibility of A-site doping in B-site modified Ba2In2O5

• Systematic exploration of A-site doping (Sr, Ca, La, Nd) in B-site modified Ba 2 In 2 O 5 reveals that compositional complexity on the Indium site significantly facilitates incorporation of multiple dopants on the Barium site • Four new phase-pure cubic perovskites and eight additional stabilizable compositions identified through comparative study of solid-state ceramic sintering, sol-gel, and autocombustion synthetic methods • Tolerance-factor analysis of successful and unsuccessful syntheses provides experimental guidelines for achieving structural stability across wide compositional space, enabling rational design pathways to high-entropy perovskite compositions The oxygen-deficient oxide Ba 2 In 2 O 5 has been extensively studied for its oxygen-ion conductor properties, and constitutes an excellent example of the temperature- and composition-induced flexibility of the perovskite family. We attempt combinations of Sr, Ca, La, and Nd ranging from one to four substituents on B-site doped derivatives of Ba 2 In 2 O 5 (up to four substituents to the indium) approached synthetically with solid-state ceramic sintering, sol–gel, and auto-combustion pathways, of which the first emerges as most reliable. We report four new phase-pure cubic perovskites and eight additional com-positions that are stabilizable with higher temperature and longer sintering times. Com-positional complexity on the indium site greatly aids the insertion of multiple dopants on the barium site. Using the ensemble of positive, partial, and negative results, we provide a tolerance-factor-informed analysis of Ba 2 In 2 O 5 and identify an area of stability for the structure where experimental modifications can be achieved all the way to high-entropy compositions.