Effect of Ti substitution on multiferroic properties of BiMn2O5

We present here the magnetic, dielectric, and electronic structural properties of Ti doped BiMn2O5 multiferroic materials. The x-ray diffraction (XRD) studies of BiMn2-xTixO5 (0 <= x <= 0.5) indicate no structural change up to x=0.5, though the lattice parameters (a and c) increase with increasing value of x. Dielectric constant and magnetization data show the evolution of new dielectric anomalies at similar to 120 K and weak magnetic feature at similar to 86 K with the Ti substitution compared to that of undoped one. However, Ti replacement vanishes the ferroelectric transition of BiMn2O5 at similar to 35 K and gradually suppresses the antiferromagnetic ordering at similar to 39 K. Polarization of Bi 6s(2) lone pair electrons is attributed to the reason behind new dielectric anomalies, whereas new weak magnetic feature at similar to 86 K is attributed to strong spin-phonon coupling. X-ray absorption spectroscopy (XAS) studies on O K, Mn K, L-3,L-2, and Ti L-3,L-2 edges of BiMn2-xTixO5 samples along with the reference compounds have been performed and compared to bestow the exact chemical states of functioning ions. The Ti L-edge spectra clearly indicate the substitution of Ti4+ ions in all samples. XRD as well as XAS data and increase in net magnetic moment coherently indicate the replacement of Mn4+ by Ti4+. (c) 2008 American Institute of Physics.