Multiferroic properties of Bi_1-xDy_xFeO₃ nanoparticles

Dysprosium (Dy)-doped BiFeO₃ (BFO) (BFDO) nanoparticles were prepared by an ethylene glycol based sol-gel method. Partial substitution of Dy (0%-20%) at the Bi site results in a change from the rhombohedral structure (x=0) to the orthorhombic structure (x=0.10,0.20) of BFO nanoparticles. The average grain size varies from 65 to 24 nm when Dy concentration increases from x=0 to x=0.20. Saturated magnetization Ms of BDFO increases with increasing Dy concentration and decreasing grain size. Moreover, dielectric properties were measured up to high frequency ∼95 MHz, and Dy dopant was found to be helpful to improve dielectric ordering and reduce loss. Surprisingly, the large magnetodielectric coefficient was found to be 4.7% in the as-prepared BFO nanoparticles, and -6.3% in Bi_0.8 Dy_0.2FeO₃ at H=100 Oe and f=75 MHz.