Effect of Ru3+ ions on the formation, structural, magnetic and optical properties of hematite (α-Fe2O3) nanorods

•Ru-doped hematite nanorods were prepared by precipitation and calcination.•Ru-for-Fe substitution (up to 2 mol%) induced a gradual elongation of nanorods.•Temperature of the Morin transition gradually rose with increased Ru doping.•Optical band gap of hematite nanorods narrowed with increased Ru doping.•Cylinder-shaped hematite particles were formed in the presence of 4 or 5 mol% Ru.