Effect of Ti substitution on multiferroic properties of BiMn2O5

Abstract

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 ∼120 K and weak magnetic feature at ∼86 K with the Ti substitution compared to that of undoped one. However, Ti replacement vanishes the ferroelectric transition of BiMn2O5 at ∼35 K and gradually suppresses the antiferromagnetic ordering at ∼39 K. Polarization of Bi 6s2 lone pair electrons is attributed to the reason behind new dielectric anomalies, whereas new weak magnetic feature at ∼86 K is attributed to strong spin-phonon coupling. X-ray absorption spectroscopy (XAS) studies on O K, Mn K, L3,2, and Ti L3,2 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+.