Systematic investigation of the proton vibrational dynamics in AB0.5M0.5O3H0.5 (A = Ba,Sr; B = Zr,Sn; M = In,Ga,Al) proton-conducting oxides

Proton-conducting perovskites are promising materials for various energy-related applications. We have recently shown that indium-doped BaZrO3 (In/BZO) contains extra contributions in its vibrational spectra, in comparison to Sc/BZO or Y/BZO, which have been interpreted as the signature of a second population of proton sites with inter-octahedra geometry. To confirm and unveil the parameters at the origin of the presence of these additional proton sites, we aim to characterize in a systematic manner the lattice and vibrational dynamics, hence the proton local environments, of a series of compositions: AB0.5M0.5O3H0.5, with A=[Ba,Sr], B=[Zr,Sn], and M=[In,Ga,Al]. The results will allow us to understand which factors among the valence orbitals, chemical hardness, or cell parameters are at the origin of the presence of the inter-octahedra proton sites in cubic perovskites.