Structural and impedance spectroscopic study of Zn-substituted Ba5CaTi2Nb8O30 tetragonal tungsten bronze ceramics

Abstract

Zn-doped tungsten bronze compounds derived from Ba5CaTi2Nb8O30, with Ba5CaTi2-xZnxNb8O30 composition (x=0; 0.04 and 0.08) were synthesized by the conventional solid-state reaction route. Both solubility of Zn in Ba5CaTi2Nb8O30 and tungsten bronze formation with the P4bm space group were verified by the Rietveld method using X-ray diffraction data. The average crystallite size was of the order of 0.08 μm according to Scherrer's formula. SEM micrographs of Ba5CaTi2-xZnxNb8O30 ceramics showed high densification, low porosity, thus a homogeneous grain distribution of different sizes over the entire surface. The average grain size was in the range of 1.3 to 1.6 μm. The frequency-dependent electrical properties were analyzed by complex impedance spectroscopy. Different types of studies such as the Nyquist plot, real and imaginary impedance, conductivity, modulus formalism, and charge carrier activation energy were used to explain the microstructure-electrical properties relationships.

Impact of rare earth (RE3+ = La3+, Sm3+) substitution in the A site perovskite on the structural, and electrical properties of Ba(Zr0.9Ti0.1)O3 ceramics

“…It has often been mentioned that the activation energy of single ionized oxygen vacancies is about (0.3–0.5 eV) and about (0.6–1.2 eV) for double ionized oxygen vacancies. 59,65,90…”

“…It has oen been mentioned that the activation energy of single ionized oxygen vacancies is about (0.3-0.5 eV) and about (0.6-1.2 eV) for double ionized oxygen vacancies. 59,65,90 Oxygen vacancies are considered as one of the mobile charge carriers and, mainly in titanates, the ionization of oxygen vacancies creates conduction electrons, a process that is described by the Kröger-Vink notation. 91…”

Studies of Structural, Dielectric, and Impedance Spectroscopy of KBT-Modified Sodium Bismuth Titanate Lead-Free Ceramics

“…These defects/gaps result in the addition of free charge carriers which can increase the conductivity at higher frequencies under the effect of the applied field. Such AC conductivity is explained according to the Jonscher’s power law. ,, …”

“…Such AC conductivity is explained according to the Jonscher's power law. 32,80,98 A ac dc n = + (13) The σ dc specifies the DC conductivity, and the second term is the frequency dependent AC conductivity. "A" refers to the polarization force, and "n" is the temperature-dependent parameter.…”

Structural, electrical, and dielectric study of the influence of 3.4% lanthanide (Ln3+ = Sm3+ and La3+) insertion in the A-site of perovskite Ba0.95Ln0.034Ti0.99Zr0.01O3

“…The activation energy of a stoichiometric ABO 3 perovskite is about 2 eV, while the E a value is 1 eV for ABO 2.95 and 0.5 eV for ABO 2.90 , 58,87,88 from the activation energy values found and presented in the table in can confirm that oxygen vacancies (OVs) are responsible for the conduction mechanism in BZT, BSmZT and BLaZT ceramics and precisely single ionized oxygen vacancies of activation energy about (0.3–0.5 eV) are responsible for the conduction at the grain boundaries and for the grain conductivity controlled by double ionized oxygen vacancies of activation energy about (0.6–1.2 eV). 86,89,90…”