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Rare‐earth (RE) (Eu3+, Gd3+, Tb3+, and Dy3+)‐doped BiFeO3 (BFO) ceramics were prepared by a modified solid‐state reaction method, which adopted higher heating as well as cooling rates during sintering process. All the fabricated samples showed ferroelectric hysteresis loops with a remnant polarization of 21–35 μC/cm2. A piezoelectric coefficient (d33) of ∼48 pC/N was obtained and this value was showed to be composition independent. The pyroelectric properties of our samples were studied as a function of temperature. Generally, the pyroelectric coefficient slightly decreased with temperature, and this is attributed to the increase of electrical conduction at higher temperatures. Among the different doped BFO ceramics, Gd‐doped samples exhibited the largest pyroelectric coefficient of 146 μC/m2K at room temperature. For the magnetic properties, slim hysteresis loop with remnant magnetizations of 0.016–0.044 emu/g were obtained in all the doped samples. Our results revealed that the RE‐doped BFO ceramics posses an improvement in both the electrical and magnetic properties. On the basis of our studies, we demonstrate that RE‐doped BFO is a potential candidate for magnetoelectric device applications.

Cobalt ferrite (CoFe 2 O 4 , CFO) nanoplatelets with a rhomboidal shape were synthesized through a facile hydrothermal route using a very low concentration precursor at low temperatures. The effects of reaction temperature and time on the morphologies as well as the sizes of the products were systemically investigated. The as-synthesized CFO nanocrystals showed a special rhomboidal shape with crystal growth along the (111) direction. The very low concentration precursor plays an important role in forming CFO nanocrystals with such special shape and ultrafine size. The single-phase CFO nanoplatelets synthesized at 180 C with size of 17 nm present high saturation magnetization (79.7 emu/g) and high coercivity (3100 Oe). The preparation conditions have significant effects on the crystal size and shape, magnetization and relaxation activation of the CFO nanoplatelets. V