Electrical and structural characteristics of lanthanum-doped barium titanate ceramics

Abstract

Single phase La-doped BaTiO 3 with the formula Ba 1Ϫx La x Ti 1Ϫx/4 O 3 : 0рxр0.20 was prepared by solid state reaction of oxide mixtures at 1350°C, 3 days, in O 2 . The tetragonal distortion in undoped BaTiO 3 decreased with x and samples were cubic for xу0.05. Both the tetragonal/cubic and orthorhombic/tetragonal transition temperatures decreased with x, but at different rates, and appeared to coalesce at xϳ0.08. The value of the permittivity maximum at the tetragonal/cubic phase transition in ceramic samples increased from ϳ10 000 for xϭ0 at 130°C to ϳ25 000 for xϭ0.06 at ϳϪ9°C. At larger x, the permittivity maximum broadened, showed ''relaxor''-type frequency dependent permittivity characteristics and continued to move to lower temperatures. Samples fired in O 2 were insulating and showed no signs of donor doping whereas air-fired samples were semiconducting, attributable to oxygen loss.

Synthesis of Barium Titanate Using Deep Eutectic Solvents

“…[1][2][3] Its high permittivity, coupled with temperature stability through the use of suitable dopants, make BaTiO3 an excellent candidate for the fabrication of multilayer capacitors. [4][5][6][7] More recently it has received renewed interest as the basis for the fabrication of lead-free piezoelectric devices. 8 Traditionally, oxide-based electroceramics such as BaTiO3 have been made via solid-state synthesis, 9 which whilst reliable, suffers from several inherent drawbacks.…”

Properties of lanthanum doped BaTiO3 produced from nanopowders

“…The literature data mainly reports the preparation of lanthanum doped BT by solid state reaction [3][4][5][6]. Among the several soft chemistry routes that can be used, the polymeric precursor method has the advantage of assuring chemical purity of the final product what is very important for final properties of obtained material.…”

Lead-Free Ferroelectric Ceramics with Perovskite Structure

“…The grain size also influences the dielectric response (Fang et al, 1993;Hoshina et al, 2008), but there are the intrinsic effects due to the introduction of cations in the A and B sites of the ABO 3 structure. More precisely, when donor-type doping of KNN with La +3 and Ta +5 is performed (Hao et al, 2009) and in BaTiO 3 (Morrison et al, 1999), the dielectric constant at the T C decreases and the transition became broad, this behavior it is not well understood but it is suggested that the many different transitions collapse at once resulting in the broad pick at T C . In the KNLNT it seems that the Ta +5 doping induces that the ε r was lower at the transition compared with pure KNN, the contribution of grain size was discarded.…”