Effects of barium substitution on the sintering behavior, dielectric properties of Ca2Nb2O7 ferroelectric ceramics

Barium-doped Ca 2 Nb 2 O 7 ceramics were prepared in the form of Ca[Formula: see text]Ba x Nb 2 O 7 (0 [Formula: see text] 0.6) by solid-state reaction. The solubility limit of barium in Ca 2 Nb 2 O 7 was found to be [Formula: see text] based on X-ray diffraction and Raman spectroscopy analysis. When [Formula: see text] 0.4, Ca[Formula: see text]Ba x Nb 2 O 7 solid solutions with a monoclinic perovskites-like layered structure (PLS) were formed, whereas beyond [Formula: see text], a secondary phase CaNb 2 O 6 was detected. The dielectric properties obviously depended on the barium substitution. With increasing barium amount, the dielectric constant increased from 33.5 for pure Ca 2 Nb 2 O 7 to 38.6 for [Formula: see text] ([Formula: see text][Formula: see text]MHz). The Curie temperature ([Formula: see text] of the [Formula: see text] sample was 1280[Formula: see text][Formula: see text][Formula: see text]5[Formula: see text]C. The phase transition was confirmed to be the second order.