Semiconducting Barium Titanate Ceramics Prepared by Boron‐Containing Liquid‐Phase Sintering

Abstract

Semiconducting BaTiO, ceramics have been prepared by adding BN as a sintering aid. Density as high as 93% of theoretical and grain size as large as 16 pm are obtained after sintering at 1160°C. Most significant is that the semiconducting BaTiO, is obtained at sintering temperatures as low as 1100°C. The low-temperature-sintered BaTiO, exhibits a positive temperature coefficient (PTC) anomaly above 120°C with a resistivity maximum at a temperature as high as 400"C, which is much higher than that of the conventional BaTiO,. The incorporation of B into the perovskite structure is negligible. Also, the presence of B at a grain boundary after sintering is believed to enhance the PTC effect.

Microstructure and microwave dielectric properties of ZnO-B2O3 added (Ca0.254Li0.19Sm0.14)TiO3 ceramics

“…Obviously, further adding ZB 2 increases the porosity, and the reason for this may be attributed to the formation and evaporation of a large amount of liquid phase [16,24]. Therefore, the density decreases with a further increase in the amount of ZB 2 , which agrees well with the change of relative density as discussed in Fig.…”

“…Since the eutectic point of ZB 2 glass is as low as 820°C, eutectic liquid was formed at this temperature during sintering process, which assisted in the densification. It has been reported [16,24] that the sintering aids containing B 2 O 3 promoted the densification by liquid phase sintering and then evaporated during the sintering process. The optimum sintering temperature formed a suitable amount of liquid phase which helped to densify the sintered sample.…”

“…Both ZnO and B 2 O 3 are staple sintering aids and are used to lower the sintering temperature of microwave dielectric ceramics [16][17][20][21][22][23][24]. However, the influence of ZnO-B 2 O 3 (ZB 2 ) addition on the sintering behavior and dielectric properties of microwave dielectric ceramics has not been fully reported so far.…”

Novel Low Loss, Low Permittivity Glass-Ceramic Composites for LTCC Applications

“…The improved relative permittivity can be attributed to the improved densification of ceramic by the addition of glasses. Generally, 30 higher wt% of glass addition decreases the relative permittivity of the glass–ceramic composites. This is due to the low relative permittivity of glass compared with that of ceramics.…”

Effects of Interactions Among BaTiO3, PVA, and B2O3 on the Rheology of Aqueous BaTiO3 Suspensions

“…To process BaTiO 3 capacitors, materials including sintering agents, the binder, and the solvent are generally required. Sintering agents are added in order to lower the high sintering temperature of BaTiO 3 ; they are usually inorganic compounds such as boron oxide (B 2 O 3 ) and CdO–Bi 2 O 3 –B 2 O 3 that have low melting points and can form liquid phases at elevated temperatures 1–3 . The binder is used to offer the ceramic tape a required green strength in the green line, and it is commonly an organic polymer 4,5 .…”