abstract
An investigation of the crystal structure, the magnetic and the piezoelectric properties of polycrystalline Bi1-xCaxFe1-x/2Nbx/2O3 (I) and Bi1-xPbxFe1-x/2Nbx/2O3 (II) systems was performed by x-ray diffraction, Mossbauer spectroscopy, vibrating sample magnetometry, and piezoresponse force microscopy. It is shown that an increasing niobium content induces a polar-to-nonpolar morphotropic boundary near x = 0.19 (I) and x = 0.3 (II). Within the polar region of the system (I), (0.15 <= x <= 0.18), the solid solutions are homogeneous weak ferromagnets whereas compounds of the system (II) do not exhibit an appreciable spontaneous magnetization. It is assumed that chemical substitutions leading to a decrease of the initial volume of the unit cell favor the stabilization of the weak ferromagnetic state within the rhombohedral ferroelectric phase. The piezoresponse is significantly enhanced near the morphotropic boundary. The piezoelectric properties of the parent antiferromagnet BiFeO3, harboring a cycloidal spatially modulated spin structure, are compared with those of the polar weak ferromagnet Bi0.82Ca0.18Fe0.91Nb0.09O3. (C) 2011 American Institute of Physics. [doi:10.1063/1.3594251]
keywords
BISMUTH FERRITE; BIFEO3 FILMS; WEAK FERROMAGNETISM; MULTIFERROICS; CERAMICS; STATE; LA
subject category
Physics
authors
Troyanchuk, IO; Tereshko, NV; Karpinsky, DV; Kholkin, AL; Kopcewicz, M; Barner, K
our authors
Andrei Kholkin
Retired Researcher
Dzmitry Karpinski (Karpinsky)
Post-doc Fellowshipacknowledgements
The authors would like to acknowledge the financial support of the BRFFI (Grant No. T10R-119 and F09K-043) and of the FCT (Grant Nos. SFRH/BPD/42506/2007). The work was also partly supported by the FLAD project 600-06/2006.