Multiferroic properties of Eu-substituted BiFeO3 fine-grained ceramics

Reference	Presenter	Authors (Institution)	Abstract
08-109	Vasile Adrian Surdu	Surdu, V.A.(University POLITEHNICA of Bucharest); Ganea, P.(National Institute of Materials Physics); Kuncser, V.(National Institute of Materials Physics); IANCULESCU, A.C.(University POLITEHNICA of Bucharest, Romania);	$B{i}_{1-x}E{u}_{x}Fe{O}_3$ (x = 0 – 0.20) powders were obtained by a sol-precipitation method, using bismuth and iron nitrates as starting materials. After thermal treatment at 600°C/1 h, well-crystallized particles with sizes ranged between 40 and 155 nm, were obtained when the $E{u}^{3+}$ content decreases from x = 0.20 to x = 0. For a substitution degree x ? 0.10 only the rhombohedral form of $BiFe{O}_3$ was identified by XRD. The increase of europium addition above this value induces the partial conversion of the rhombohedral (R3c) modification into the orthorhombic (Pnma) polymorph. From these powders, fine-grained ceramics were prepared by spark plasma sintering (SPS). FE-SEM investigations indicated that the presence of $E{u}^{3+}$ as solute on Bi sites determines a strong decrease of the grain size from 925 nm for x = 0 to 173-217 nm for x ? 0.05. The ceramics exhibit decreased values of permittivity when increasing the $E{u}^{3+}$ content. The structural transition has a beneficial effect on the dielectric losses which decrease with about one order of magnitude from tan? ~ 0.07 (x = 0) to ~ 0.005 (x = 0.20) at fixed frequency f = 100 kHz. In the temperature range of 400 – 500K, relaxation phenomena occur for x ? 0.15. Magnetic hysteresis loops collected on the ceramics showed an antiferromagnetic behaviour for x = 0 and x = 0.20 and a weak ferromagnetic behaviour for 0.05 ? x ? 0.15.
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