  Magnetoelectric coupling in the polycrystalline antiferromagnets
CuFe0.95Rh0.05O2 and CuFeO2 has been investigated. For both samples, electric
polarization was observed in the absence of an applied external magnetic field
demonstrating that for multiferroic research ceramics are worth to be studied.
The observed magnetodielectric effect for CuFe0.95Rh0.05O2 in the electrically
polar phase supports the existence of a noncollinear antiferromagnetic state.
Interestingly, the electric polarization of this sample can be suppressed by a
magnetic field. The temperature dependence of the relative magnitude of the
magnetodielectric effect shows a discontinuity, clearly indicating different
mechanisms of the magnetodielectric couplings in polar and paraelectric
antiferromagnetic states.
