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

Abstract

Lead-free ceramic materials produced from bismuth sodium titanate (Na0.5Bi0.5TiO3, NBT)–bismuth potassium titanate (K0.5Bi0.5TiO3, KBT) have been developed through a solid-state reaction technique. The structural, dielectric, and piezoelectric characteristics of the ceramic materials were analyzed. Based on the XRD investigation, the morphotropic phase boundary (MPB) was determined for the composition (x (%) = 16 and 20). The effects of the KBT phase on the NBT lattice were examined using the charge density distribution. Furthermore, the dielectric properties indicated the presence of a negative dielectric constant (εr′) as a function of frequency between 1 kHz and 2 MHz. Negative permittivity was observed globally in the (1 – x)­NBT–xKBT ceramic which reflects the effect of the dielectric resonance. The grain conduction effect is revealed through the complex impedance spectrum in the form of a semicircular arc within the Nyquist plot. In addition, the samples studied revealed a non-Debye relaxation phenomenon. The relaxation time was determined based on the Vogel-Fulcher law for all samples. DC conductivity was carried out on the ceramics material and revealed that the resistance decreases with increasing temperature indicating a negative temperature coefficient of resistance. The AC conductivity as a function of frequency for different temperatures suggests the presence of a thermally activated conduction mechanism. The activation energy has been determined based on the Arrhenius plot of the DC electrical conductivity as well as the relaxation frequency.

(1-x)(Na₀.₅Bi₀.₅)TiO₃-xCaTiO₃ ceramics: Investigating structural and microstructural features for enhanced dielectric properties

“…This phenomenon may be attributed to the introduction of new diffusion centers associated with the higher doping concentration [ 41 , 42 ]. Furthermore, the spatial distribution of electron density, particularly in the context of calcium doping, plays a crucial role in understanding the variation of the dielectric constant.…”

“…This trend is attributed to the prevalence of various defects and oxygen vacancies at the grain boundaries. Perovskite materials, in general, demonstrate enhanced conductivity primarily due to these oxygen vacancies [ 19 , 42 ]. Commonly, the sintering process facilitates the volatilization of A-site cations, leading to the formation of oxygen vacancies [ 9 ].…”

Thermal Stability and Non-Linear Optical and Dielectric Properties of Lead-Free K0.5Bi0.5TiO3 Ceramics

“…As previously shown [40], bulk density is the most crucial factor for polycrystalline KBT ceramics. However, KBT density may be underestimated and restrict the ferroelectric properties [40][41][42][43][44]55] due to the formation of impurity phases in ceramics sintering. Therefore, KBT manufacturing with the lowest possible impurity phase content is imperative [45][46][47][48][49]56].…”

Synthesis and Characterization of Photocatalyst Nanocomposite for the Degradation of Organic Pollutants in Wastewater

“…One solution was to apply the doping with oxides that can be easily dispersed in an organic medium and homogeneously loaded onto the supporting material as copper oxide (CuO) with a band gap of ~1.2 eV (Alp et al, 2019;Mesrar et al, 2023). Previous studies have successfully synthesized photocatalyst nanocomposite layers supported by different semiconductor oxides, including CuO/Fe 2 O 3 /Polystyrene.…”