Low temperature sintering and microwave dielectric properties of CoZrNb2O8 ceramics with H3BO3 addition

Abstract

The effects of H 3 BO 3 additive on the sintering behavior, phase composition, microstructure and microwave dielectric properties of CoZrNb 2 O 8 ceramics were investigated based on the research of pure-phase CoZrNb 2 O 8 (CZN) ceramics. When 2.5 wt% H 3 BO 3 was added to CoZrNb 2 O 8 ceramics, the sintering temperatures significantly decreased from 1250 to 1200°C due to the formation of liquid phase. The ceramic sintered at 1200°C for 4 h exhibited excellent microwave dielectric properties of e r = 21.62, QÁf = 40,200 GHz and s f = -16.38 ppm/°C . Compared to the results of CZN ceramics, the H 3 BO 3 additives effectively lowered the sintering temperature of CZN ceramics due to the liquid phase effect without detrimental effect on the properties.

Design of a High-Efficiency and -Gain Antenna Using Novel Low-Loss, Temperature-Stable Li2Ti1–x(Cu1/3Nb2/3)xO3 Microwave Dielectric Ceramics

“…Although the mechanism of the changes in TCF is not yet entirely clear at present, it seems reasonable to believe that the liquid phase of B 2 O 3 is the cause of the changes of TCF. Similar phenomena have been reported in some other material systems after the addition of sintering aids. ,,,, Notably, the 3 wt % H 3 BO 3 -doped LTCN 0.2 ceramic sintered at 860 °C (which was 280 °C lower than that of undoped LTCN 0.2 ) exhibited a dense microstructure and superior performances of ε r ≈ 21.0, Q × f ≈ 51,940 GHz, and TCF ≈ +1.4 ppm/°C (25–85 °C).…”

“…Similar phenomena have been reported in some other material systems after the addition of sintering aids. 22,23,46,47,53 Notably, the 3 wt % H 3 BO 3 -doped LTCN 0.2 ceramic sintered at 860 °C (which was 280 °C lower than that of undoped LTCN 0.2 ) exhibited a dense microstructure and superior performances of ε r ≈ 21.0, Q × f ≈ 51,940 GHz, and TCF ≈ +1.4 ppm/°C (25−85 °C).…”

“…Among them, the last method is generally considered to be an effective, low-cost, and versatile method capable of reducing the sintering temperatures of ceramics . It is worth mentioning that H 3 BO 3 is a common and effective sintering aid with a low melting point. − Thus, it seems reasonable to believe that adding a H 3 BO 3 additive can also effectively bring about a decrease in the sintering temperature of the LTCN x system. Effects of the H 3 BO 3 content on crystalline structures, microstructures, densities, and microwave dielectric properties of the LTCN 0.2 ceramic (optimal performing sample) are investigated in this work.…”

Enhanced high dielectric characteristics tri‐layered structural ceramics for 5G/6G communications

“…(The size of the spheres in the diagram represents the value of the dielectric constant; the larger the sphere, the higher the dielectric constant of the dielectric ceramic. ) 4,19–20,33,41,54–85 …”