Influence of doping and doping level on magnetoelectric coupling in layered composites Tb_1-xDy_xFe_2-y/Ba-Ti_1-zM_zO_3+δ (M = Fe, Cr, Mn, Co)

Magnetoelectronic Lab, Nanjing Normal University, Nanjing, 210097, P.R. China

Corresponding author: zhangning@njnu.edu.cn

Received: 5 July 2008
Revised: 4 April 2009
Accepted: 26 March 2010
Published online: 17 May 2010

Abstract

Perovskites BaTi_1-zM_zO_3+δ (M = Fe, Cr, Mn, Co) has been sol-gel synthesized. Their transformation point of ferroelectric to paraelectric and the latent heat of the transformation were found a little lower than those for pure BaTiO₃ (BTO), respectively. Layered composites Tb_1-xDy_xFe_2-y–BaTi_1-zM_zO_3+δ have been fabricated. Their magnetoelectric (ME) effect has been investigated. All the bilayers containing the doped BTO displayed a stronger ME effects than that containing pure BTO does. The bilayer Tb_1-xDy_xFe_2-y–BaTi_0.99Cr_0.01O_3+δ was observed to show a larger ME coupling in the composites containing other doped BTO. While Tb_1-xDy_xFe_2-y–BaTi_0.985Fe_0.015O_3+δ showed the largest ME effects in the bilayers Tb_1-xDy_xFe_2-y–BaTi_1-zFe_zO_3+δ (0 ≤ z ≤ 0.02). Additionally, the ME voltage coefficient for the trilayers Tb_1-xDy_xFe_2-y–BaTi_0.99M_0.01O_3+δ–Tb_1-xDy_xFe_2-y was observed to be two or three times larger than that observed in the bilayers composed by the same substances. Theoretical analyses have been given for these observations. All the results suggest that the doped BTO can be a new choice of piezoelectrics in fabricating layered ME composites.