Magnetic and luminescent properties of barium fluoride nanopowder obtained by electron-beam evaporation in low-pressure gas

Mesoporous amorphous-crystalline nanopowders of BaF$_{2}$ with the specific surface area up to 34.8 m$^2$/g were obtained using evaporation by a pulsed electron beam in vacuum. Influence of the thermal annealing of the BaF$_{2}$ nanoparticles in air at the temperatures from 200 to 900$^{\circ}$C on the size and morphology of the particles and changes in their magnetic and luminescent properties was studied. The paramagnetic response of the BaF$_{2}$ nanopowder was found to transform to the ferromagnetic response after annealing at 900$^{\circ}$C. The appearance and transformation of the magnetic response in nanopowders made of BaF$_{2}$, which is diamagnetic as the bulk material, are ascribed to the appearance of radiation-induced and structural defects during the synthesis process by pulsed electron-beam evaporation.