Study of d0 magnetism of BaF2 nanopowder after thermal and radiation exposure

[Display omitted] •Mesoporous nanocrystal BaF2 nanopowder have been obtained with the pulsed electron beam evaporation.•The nature of d0 magnetism in a nanopowder of barium fluoride is investigated.•The effect of thermal annealing and electron irradiation on various properties of a nanopowder is studied. Mesoporous nanocrystal BaF2 nanopowders (NPs) have been obtained with the pulsed electron beam evaporation (PEBE) technique. The transformation of the structure and morphology of BaF2 nanoparticles (NPles) induced by thermal annealing in air at temperatures of 200, 400, and 900 °C has been monitored with the XRD, SEM, and HRTEM methods. The HRTEM analysis has shown the presence of three polymorph phases (cubic, octahedral, and hexagonal) in the unannealed NP. Upon the transition into the nanoscale, diamagnetic (DM) BaF2 (in the volume state) has demonstrated both paramagnetic (PM) and ferromagnetic (FM) responses at room temperature. The thermal analysis (TA) has confirmed the strong adsorption of CO2 while synthesizingthe BaF2 NP via PEBE method and adsorption of different NOx oxides following irradiation of the BaF2 NP (in air by 700 keV electrons) The appearance of the FM contribution in the diamagnetic BaF2 NP after annealing at a temperature of 600–900 °C is likely associated with the achievement of the percolation threshold with an increase of the BaO oxide concentration. This is in agreement with the well-known theoretical predictions of d0 magnetism in N-doped (C-doped) BaO. The appearance and variations of the FM contribution to the BaF2 NP irradiated by 700 keV electrons are likely connected with an increase of the NOx oxide concentration (due to an increase of the time of electron irradiation), which confirms the hypothesis on the appearance of the FM response in solid-state N (C)-BaO solutions. The FM decrease with time is indicative of the surface character of d0 magnetism in the barium fluoride under study.