Structural and Dielectric Properties of Ba_1−xLa_x(Zn_1/3Nb_2/3)O₃ Solid Solutions

Abstract

Herein, lanthanum doping effects on the structural, dielectric, and electrical properties of Ba1−xLax(Zn1/3Nb2/3)O3 (BZN) solid solutions are focused upon. The La contents which are varied in the range of 0.02–0.20 exhibit a solubility limit of x = 0.02. Although minor phases of Ba5Nb4O15 and Ba3LaNb3O12 appear for samples doped with La contents of x = 0.05 and x = 0.10, they play no remarkable role for the enhanced structural and dielectric properties of BZN. The La doping content of x = 0.02 succeeds in increasing the crystallite size by 51.16% and lowering the microstrain by 34.18% and defect concentration by 63.10%. La‐doped BZN ceramics display higher values of relative density and electrical conductivity. The analyses of the dielectric spectra as a function of temperature display dielectric relaxation behavior above 120 °C. In the temperature range of 20–120 °C, La doping changes the temperature coefficient of dielectric constants from +30 ppm °C−1 in pure samples to −341 ppm °C−1 in samples doped with La contents of x = 0.10. The enhancements in structural parameters, density values, and dielectric responses that are achieved via La doping make BZN ceramics more suitable for electronic device fabrication.

Crystal Structure, Chemical Bond, and Microwave Dielectric Properties of Ba1−xSrx(Zn1/3Nb2/3)O3 Solid Solution Ceramics

“…The relative density of the samples showed an overall increasing trend with the increasing sintering temperature. Nevertheless, the samples sintered at 1525 • C did not follow this trend, which was due to the decreased density caused by the evaporation of Zn 2+ at higher temperatures [17]. For all samples sintered at 1425-1500 • C, it could be observed that the relative density firstly increased to the peak value at x = 0.2 and then decreased sharply with the increase in Sr 2+ concentration.…”

“…Microwave dielectric ceramics with the general formula of A(B 1/3 B 2/3 )O 3 (A = Ba, Sr, Ca; B = Zn, Mg, Mn, Fe, Co, Ni, Cu; B = Nb or Ta) have been widely studied for their excellent microwave properties [9,12,13]. In recent years, in order to further promote the microwave dielectric properties and reduce the densification sintering temperature of ceramics, ion substitution and various additives were investigated in large-scale applications [14][15][16][17][18][19][20]. Especially in practical applications, it is important that the τ f value should be adjusted to near zero.…”