The influence of Bi content on dielectric properties of Bi4–xTi₃O12–1.5x ceramics

Abstract

A kind of lead-free dielectric materials, such as the bismuth layered perovskite-type structure of Bi 4Àx Ti 3 O 12À1:5x ðx ¼ 0:04; 0:02; 0; À0:02; À0:04Þ, was prepared by the conventional solid-state method at 800 C and sintered at 1100 C. The variation of structure and electrical properties with different Bi concentration was studied. All the Bi 4Àx Ti 3 O 12À1:5x ðx ¼ 0:04; 0:02; 0; À0:02; À0:04Þ samples exhibited a single structured phase. SEM could be a better approach to present the microstructure of Bi 4Àx Ti 3 O 12À1:5x ðx ¼ 0:04; 0:02; 0; À0:02; À0:04Þ ceramics. It could be found that the grain size of Bi 4:02 Ti 3 O 12:03 sintered at 1100 C was smaller than that of others among the five samples through grain size mechanics. Through impedance spectra analysis, we knew, when the Bi content was fixed, that the dielectric constant and the loss values increased with the decrease of frequency. The Curie temperature of the five samples was about 670 C. In particular, while at the frequency of 100 kHz, the lowest loss was 0.001 when Bi content was 3.98. The Bi 4:02 Ti 3 O 12:03 ceramics with the minimum grain size had highest dielectric constant and the relatively low loss. Due to its high Curie temperature, high permittivity and low loss, the Bi 4 Ti 3 O 12 (BIT) ceramics have a broad application prospect in high density memory, generator, sensor, ferroelectric tunnel junctions and so on.

Production of Nanometric Bi4Ti3O 12 Powders: from Synthesis to Optical and Dielectric Properties

“…At higher frequencies (close to 1 MHz, focused in Figure 12-A), electronic, ionic and even orientation polarization contribute to the dielectric constant 36 . For this condition, ε' seems to be close to 115 (25ºC, 1 MHz), which agrees with previous reports from literature 59 . Since the temperature does not significantly affect the ionic and electronic polarization 36 , ε' does not considerably increase with temperature at high values of frequency.…”