Photoluminescence behavior of YPO4:Tb3+ crystallized in monoclinic, hexagonal or tetragonal phase obtained by hydrothermal process

•YPO4 nanoparticles were synthesized by hydrothermal process.•Effects of varying pH, temperature and dopant concentration on morphology were studied.•Crystalline structures of YPO4 depend on the pH and temperature of synthesis.•Hexagonal phase of YPO4:Tb3+ powders is dependent on the terbium quantity and pH value.•The morphology depends on the crystal structure.