Features of the structure, microstructure, radio-emitting and radio-absorbing properties of mechanically and non-mechanically activated BiFeO$_3$ ceramics

By the method of the two-stage solid-phase synthesis from a stoichiometric mixture of the bismuth and iron oxides, mechanically and non-mechanically activated samples of bismuth ferrite ceramics were prepared. The phase composition of the ceramic samples is predominantly BiFeO$_3$, while Bi$_{25}$FeO$_{40}$ and Bi$_2$Fe$_4$O$_9$ are recorded in minor amounts, the proportion of the latter decreases due to mechanical activation. Mechanical processing of the samples expands the range of linear sizes of microparticles. It has been established that mechanically activated bismuth ferrite ceramics absorb electromagnetic microwave energy up to -16 dB, while the samples of the original material absorb up to -25 dB. Both ceramic samples are capable of emitting a weak electromagnetic field, which decreases with increasing height above the sample.