Interactions of Ba2YCu3O6+x with SrTiO3 substrate

► Experiments performed on powders with intimate mixing, any plausible chemical reactions were promoted. ► Ba2YCu3O6+x+SrTiO3 → zBa,Sr)3YTi2O8.5+(Ba,Sr)2YCu3O6+x+ (Ba,Sr)TiO3+(Ba,Sr)2TiO4 +CuO. ► Reaction products between Ba2YCu3O6+x and SrTiO3 provide references for SEM and TEM interface studies. ► Crystal chemistry of ((Ba,Sr)3YTi2O8.5, (Ba,Sr)2YCu3O6+x, (Ba,Sr)TiO3, and (Ba,Sr)2TiO4 studied.