Dielectric properties and exploration of self-compensation mode of Tb in BaTiO3 ceramics

Abstract

The self-compensation mode and dielectric properties of the nominal (Ba1-xTbx)(Ti1-xTbx)O3 (0.05 ≤ x ≤ 0.20) ceramics (BTTT) were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), temperature-dependent Raman spectroscopy and electron paramagnetic resonance (EPR), dielectric and electrical measurements. The solid solution limit of Tb in BTTT was determined to be x = 0.12 by XRD. The variation in unit cell volume (V0) with x satisfied Vegard-s law. In the case of Ba/Ti = 1, a complete self-compensation mode of Tb3+ in BaTiO3 could not be formed like Eu3+ or Dy3+ because Tb ions in BTTT coexisted in the mixed-valence states of Ba-site Tb3+ and Ti-site Tb4+. The roomerature resistivity decreased with increasing x owing to a gradually enhanced Tb3+ donor effect. An X5S specification with medium dielectric stability was achieved at x = 0.05. This ceramic is a promising dielectric for a higher room temperature permittivity (ϵ′RT = 1190), a very low dielectric loss (tan λ <0.02), and a nearly invariant ϵ′ in the frequency range of 102 to 105 Hz.