Ferroelectric Bi4Ti3O12 and Bi4−x La x Ti3O12 ceramics prepared by a new sol-gel route

Abstract

Ceramics of bismuth titanate, Bi 4 Ti 3 O 12 (BIT) and the La-doped series, Bi 4−x La x Ti 3 O 12 (xBLT) with x= 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, and 0.75, have been synthesized by a new sol-gel process based on ethylene glycol. La-doping is found to reduce the temperature of the formation of pure Bi-layer-structured phase from 600°C in BIT and low La-doped xBLT (x=0.1-0.3) to 500°C in high La-doped xBLT (x=0.4-0.75). Increasing the La-content in the xBLT ceramics decreases the contribution of the space charge polarization to the apparent dielectric permittivity. The ceramics of xBLT prepared by this sol-gel route exhibit improved dielectric properties, with a higher room temperature dielectric constant and lower losses up to high temperatures.

Review and Perspectives of Aurivillius Structures as a Lead-Free Piezoelectric System

“…The mixture at practically atomic level favors the reaction to synthesize precursors at low temperatures, allowing the control of particle size and shape. Thus, different compositions with Aurivillius-type structure were synthesized, at temperatures that can range from 525 to 700 • C [12][13][14][15][16] [24]. In other cases, the synthesis temperature is decreased by obtaining an amorphous powder after milling [25][26][27].…”

Thermal, Microstructure and Dielectric Behavior of La-Modified Bismuth Titanate Ceramic

“…Curie Among the all ceramic samples, maximum ɛ r of 5812 was observed for x = 0.60, at T c of 520 0 C. It was also observed that BLT samples compared with our previously reported BT (x = 0) ceramics [10] possess a higher  r indicating that La plays an important role in the electrical properties of the BT layers. Doping BT with La has a strong influence on the dielectric behavior of the material even at low and high concentration [13].…”

Enhanced piezoelectric performance of Cr/Ta non-equivalent co-doped Bi 4Ti 3O 12-based high-temperature piezoceramics

“…At present, there are two main ways to solve the above problems and modify the properties of the BIT ceramics. One is modification through component design, such as doping substitution at the A or B-site [14,15]. Element doping is an effective modification method that can significantly affect the microstructure and improve piezoelectric and ferroelectric properties [16−18]; the other is modification through preparation processes, such as the molten salt method [19].…”

“…Element doping is an effective modification method that can significantly affect the microstructure and improve piezoelectric and ferroelectric properties [16−18]; the other is modification through preparation processes, such as the molten salt method [19]. The B-site modification is one of the most effective modification methods, which introduces high-valence cations such as Nb 5+ , W 6+ , and Ta 5+ [14,20,21] or co-doped cations such as Zn 2+ /Nb 5+ , Cu 2+ /Nb 5+ , and Cu 2+ /Ta 5+ [22−24] into the B-site of BIT to enhance piezoelectric activity. Furthermore, some studies indicate that non-equivalent doping, where high-valence ions replace low-valence ones, can inhibit the formation of oxygen vacancies and thus enhance electrical resistivity at high temperatures [25].…”