Surface investigations of selected materials by low-energy ion scattering technique

Surfaces of three selected materials were investigated by means of low-energy ion-scattering technique: (1) the magnetite (Fe3O 4) exhibiting the so-called Verwey transition (Tv (bulk) = 125 K) accompanied by a small cubic-monoclinic crystal distortion, (2) the intermetallic compound NdMn2 undergoing an antiferromagnetic- paramagnetic phase transition (TN = 104 K) accompanied by a large crystal distortion with a volume change of 1%, and (3) the typical insulator BaTiO3 with two structural transitions below 300 K. The primary energy of the (Ne+, Ar+) ion beam was in the range of 4-8 keV, and the low-energy ion-scattering spectra were collected in the temperature range of 85-300 K. A large influence from the Verwey transition on the neutralization and re-ionization of scattered ions from magnetite surface was observed, while no visible change at the magnetic phase transition in NdMn 2 was revealed in the low-energy ion-scattering spectra. A strong dependence of the characteristics of the low-energy ion-scattering spectra on the irradiated time was observed for BaTiO3 indicating that this surface was heavily charged by ion bombardments.