PTCR effect of solid solutions based on the (1-x)BaTiO3xNa0.5Bi0.5TiO3 system


Chem. Met. Alloys 3 (2010) 120-125


O.I. Vyunov, T.O. Plutenko, A.G. Belous, A.V. Bilousko


The structure and electrophysical properties of solid solutions based on the (1‑x)BaTiO3xNa0.5Bi0.5TiO3 ((1‑x)BTxNBT) 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)BaTiO3xNa0.5Bi0.5TiO3 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)BaTiO3xNa0.5Bi0.5TiO3 ceramics.



Resistance of the grain bulk (1), outer layer (2), grain boundary (3) and overall resistance (4) of (1‑x)BaTiO3-xNa0.5Bi0.5TiO3 (x = 0.09) ceramics.



Crystal structure / PTCR effect / Heterogeneous structure / Impedance analysis