The effect of A-site and B-site ion substitutions on the temperatures of ferroelectric and magnetic phase transitions in multiferroic PbFe0.5Nb0.5O3

In the present study we diluted either A- or B- sublattice of perovskite multiferroic PbFe
_0.5
Nb
_0.5
O
₃
(PFN) and studied the change of the magnetic and ferroelectric phase transition temperatures caused by such dilution. A-site substitutions (Ba, Ca) lead to the smearing of the permittivity-temperature maximum and lower its temperature T
_m
. Addition of Ti to PFN increases T
_m
, decreases the diffusion of permittivity maximum and lowers the temperature of the transition between rhombohedral (monoclinic) and tetragonal ferroelectric phases. Both A-site and B-site substitutions in PFN lead to lowering of its Neel temperature T
_N
. However above a certain compositional threshold fast lowering of T
_N
stops and a new magnetic state with comparatively high (~50 K) transition temperature becomes stable in a rather wide compositional range.