Dielectric properties and microstructures of non-reducible high-temperature stable X9R ceramics

New X9R dielectrics based on the precursors of (1 − x) BaTiO3–xLiTaO3 (BT–xLT) compositions and containing no lead and bismuth constituents were successfully prepared in this study. After sintering at 1150–1250 °C in a reducing atmosphere of 97%N2–3%H2, major phases including BaTiO3 and Ba2LiTa5O15 and a minor phase of Li2TiO3 were identified in the sintered ceramics. The intensities of the XRD peaks corresponding to the Ba2LiTa5O15 phase rose with the increasing x value in the precursors. The grain sizes of the sintered ceramics appeared to fall in the range between 0.3 and 0.5 μm and slightly increased with the x value of the BT–xLT ceramics. The best composition in term of dielectric properties was found in the BT–0.25LT ceramic, which was marked with a dielectric constant of 895, tan δ of 1.01% and 7.1%, TCCs of −3.04% and −14.80%, and electrical resistivities of 9.9 × 1012 and 1.6 × 1012 Ω cm, respectively at 25 °C and 200 °C.