Room temperature magneto-dielectric coupling in the CaMnO 3 modified NBT lead-free ceramics

The sol–gel prepared (1- x )Na 0.5 Bi 0.5 TiO 3 -( x ) CaMnO 3 ( x = 0, 0.03, 0.06, 0.12) compositions show a Rhombohedral ( R3c ) phase up to x = 0.06 while a mixed rhombohedral ( R3c ) and orthorhombic ( Pnma ) phases for the x = 0.12. The lattice volume consistently decreased with an increase in the CaMnO 3 content. The phase transition temperature ( T c ) decreased with an increase in the CaMnO 3 compositions. The room temperature dielectric constant increased, and loss decreased for the x = 0.03 composition due to a decrease in the oxygen vacancy and Bi loss confirmed by the valence state study (XPS). All the compositions show a variation of the room temperature dielectric property with an application of magnetic field confirming a magnetodielectric coupling. The x = 0.06 composition shows the highest negative magnetodielectric coupling constant ( MD %) of 3.69 at 100 kHz at an applied field of 5 kG.