Characterization of Lanthanum‐Doped Barium Titanate Ceramics Using Impedance Spectroscopy

TLDR

Electrical properties of La‑doped BaTiO₃ (x = 0.03 and 0.20) were examined by impedance spectroscopy after heat treatment in O₂, Ar, and air at 1350 °C. Oxygen‑heated samples were insulating, argon‑heated samples were semiconducting regardless of composition, and air‑heated samples showed intermediate, composition‑dependent, inhomogeneous behavior that can be modeled by oxygen nonstoichiometry and mitigated by lower‑temperature sintering or post‑annealing in oxygen.

Abstract

The electrical properties of two single‐phase, lanthanum‐doped BaTiO 3 compositions, x = 0.03 and x = 0.20, in Ba 1– x La x Ti 1– x /4 O 3 were investigated by impedance spectroscopy after heat treatment in oxygen, argon, and air at 1350°C. Samples heated in oxygen were electrically insulating, whereas those heated in argon lost oxygen and were semiconducting at room temperature, irrespective of x . Samples heated in air showed intermediate electrical properties and also were electrically inhomogeneous; the two compositions showed different electrical behaviors, and a model for each, based on oxygen nonstoichiometry within the ceramics, is proposed. Oxygen deficiency in samples sintered in air was avoided by heating at 1200°C, instead of 1350°C. Alternatively, oxygen lost from ceramics heated in air at 1350°C was regained by postannealing in oxygen at 1350°C.