Engineering crystal structure and spin-phonon coupling in Ba1-xSrxMnO3

•We have synthesized polycrystalline Ba1-xSrxMnO3: x = 0 to 0.6 using solid state reaction route.•We have explored crystallographic and magnetic phase diagram of Ba1-xSrxMnO3.•The system undergoes a series of crystallographic phase transitions 2H → 9R → 4H as a function of doping (Sr).•All compositions exhibit para-to-antiferromagnetic phase transition with TN ∼ 59–266 K.•A few phonons in compositions with x = 0.10 to 0.50 exhibit anomalies, arising from the spin-phonon coupling.