Estimating Ni valence with magnetometry in solid‐state reactive sintered yttrium‐doped barium zirconate

Abstract Ni is known to have a significant impact on the sintering and microstructure evolution in yttrium‐doped barium zirconate (BZY) and yet details of its specific role remain unclear. The present study examined the valence state of Ni in solid‐state reactive sintered BZY prepared with different amounts of Ni, formulated for deliberate substitution of Ni for Zr : BaZr 0.8−x Y 0.2 Ni x O 3− δ with x = 0.005, 0.01, 0.02, 0.03, 0.04 (approx. 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%). Quenching from revealed transient BaY 2 NiO 5 phase was present in the microstructure for all concentrations of Ni studied here. Energy‐dispersive X‐ray spectroscopy identified Ni segregation in grain‐boundary regions upon completion of the solid‐state reactive sintering process, and magnetometry is used to show that low‐spin Ni 3+ predominantly substitutes for Zr 4+ .