depicts the microstructure of a conventional BCZT sample sintered at 1500 °C . The sample consists of the matrix BCZT as well as the CaTiO3 and a polytitanate secondary phase, similarly as the calcined sample described above. The presence of the polytitanate secondary phase suggests an intrinsic B-site excess in the sample, which might be caused by milling abrasion, hygroscopicity of the carbonates, A-site cation sublimation at high sintering temperatures , or impurities from the precursors. A strong reduction in the amount of the polytitanate phase was achieved by adding 1% excess A-site cations into the system (Figure and). However, this measure should be carried out with care, since overcompensating for the intrinsic B-site excess could result in the formation of the (Ba,Ca)2(Zr,Ti)O4 Ruddlesden-Popper-type anti-phase boundaries or a separated (Ba,Ca)2(Zr,Ti)O4 secondary phase. These are water-soluble and are indicated by open grain boundary structures visible in SEM images . The absence of these features in our 1% A-site excess sample suggests that the resulting composition is close to the desired stoichiometric ratio of A:B=1:1.