Structure and properties of various fast neutron irradiated magnets

Neutron irradiation allows the materials to transform to a state, in which the properties of material become different from an initial state. This paper presents the results of neutron irradiation of several magnetic materials including intermetallic compounds Nd₂Fe₁₄B and Er₂Fe₁₄B, multiferroics BiFe_0.95Mn_0.05O₃ and Bi_0.85La_0.15FeO₃, oxides LiMn₂O₄ and Li_0.9FePO₄. The fast neutrons (E_eff > 0.1 MeV) have been used in a fluence range from 1 × 10¹⁸ n/cm² to 2 × 10²⁰ n/cm² at 340 K Er₂Fe₁₄B alloy becomes amorphous under irradiation, that results in the reduction of Curie temperature to about 200 K. Irradiation destroys charge ordering in LiMn₂O₄ leading to the transformation from an incommensurate antiferromagnetic to a commensurate ferrimagnetic structure. Neutron irradiation of BiFe_0.95Mn_0.05O₃ oxide is accompanied by decreasing the amount of impurity phases. On the contrary, in Bi_0.85La_0.15FeO₃ fast neutrons result in the appearance of impurity phases. Neutron irradiation distinctly affects the lattice parameters of Li_0.9FePO₄ compound even with the relatively low fluence.