Orientation dependence of magnetoelectric coefficient in 1-3-type BaTiO3/CoFe2O4

Orientation dependence of magnetoelectric coefficient αE33 in 1-3-type BaTiO3/CoFe2O4 composites was calculated in arbitrary directions by three-dimensional coordinate transformation method. The space distributions of pc11′, pc12′, e31′ for piezoelectric phase and mc11′, mc12′, q31′ for magnetic phase were obtained independently using relative experimental data and original matrices for 4mm BaTiO3 and m3m CoFe2O4. Elastic stiffness coefficients show little orientation differences, while e31′ and q31′ exhibit high dependence on crystal orientation, with the MAX absolute e31′ = 2.96 C/m2 and the MAX q31′ = 556 × 10−12 m/A are found at θ = 0° and θ = 0°, ϕ = 45°, respectively. For space distribution of αE33′, BaTiO3||[0 0 1]/CoFe2O4||[0 0 1] combination has the maximum value which applies to both 1-3 p/m (1.485 V/A) and 1-3 m/p composites (1.529 V/A). Volume fraction is quite independent of orientations of both piezoelectric and magnetic phases and the volume fraction for magnetic phase f around 0.5 obtains the largest αE33. The results suggest an approach to significantly enhancing magnetoelectric coefficient of composite multiferroic materials through crystal orientation controls of single crystals and textured ceramics.