PTCR effect of solid solutions based on the (1-x)BaTiO₃–xNa_0.5Bi_0.5TiO₃ system

Chem. Met. Alloys 3 (2010) 120-125

https://doi.org/10.30970/cma3.0130

O.I. V’yunov, T.O. Plutenko, A.G. Belous, A.V. Bilous’ko

The structure and electrophysical properties of solid solutions based on the (1‑x)BaTiO₃–xNa_0.5Bi_0.5TiO₃ ((1‑x)BT–xNBT) system (0 ≤ x ≤ 0.6) were studied. Bulk samples were prepared by the solid-state reaction technique. Samples were sintered in air and in N₂ atmosphere with low concentration of H₂. The phase composition and the crystal structure were examined by X‑ray powder diffraction for samples sintered in air. X-ray powder diffractometry (XRPD) analysis showed that in the (1‑x)BaTiO₃–xNa_0.5Bi_0.5TiO₃ system a slightly increases, whereas c decreases with the substitution of Na and Bi ions for Ba ions. The permittivity was investigated in wide frequency and temperature ranges. Impedance analyses of samples sintered in N₂/H₂ atmosphere indicated that both the grain boundary and the outer layer region contribute to the positive temperature coefficient of resistivity (PTCR) effect in (1‑x)BaTiO₃–xNa_0.5Bi_0.5TiO₃ ceramics.

Resistance of the grain bulk (1), outer layer (2), grain boundary (3) and overall resistance (4) of (1‑x)BaTiO₃-xNa_0.5Bi_0.5TiO₃ (x = 0.09) ceramics.

Keywords

Crystal structure / PTCR effect / Heterogeneous structure / Impedance analysis