Microstructure and Electric Properties of Bi2O3-Doped (K0.5Na0.5)NbO3 Lead-Free Ceramics

Abstract

In this paper, Bi2O3-doped (K0.5Na0.5)NbO3 (x = 0.1, 0.2, 0.3, 0.4) lead-free ceramics are prepared by a conventional solid-state reaction and analyzed by studying the structure, ferroelectric, and piezoelectric properties. It is found that the doping of Bi2O3 increases the proportion of the trigonal phase in KNN ceramics, thus enabling the construction of KNN ceramics with an orthogonal–trigonal phase boundary at room temperature. At the same time, doping with Bi2O3 can reduce the grain size and improve grain size uniformity of the ceramics. The KNN-0.1%Bi2O3 ceramic has the best piezoelectric properties in all composition; the results are as follows: d33 = 121pC/N, kp = 0.474, kt = 0.306.

Optical and Electrical properties of KNN-SBN:Ho/xYb Transmittance Luminescent Ferroelectric Ceramics

“…In addition, the introduction of the second component of ABO3 type has a great influence on the phase structure and grain size, and the divalent ions in the A and B positions can effectively control the grain growth of ceramics. For example, Sr 2+ can improve the ferroelectric properties of KNN ceramics [9], and Bi2O3, as a sintering agent, can effectively reduce the sintering temperature of ceramics, decrease the grain size, and increase the ceramic density [10]. While considering transparency, the introduction of Ho 3+ can absorb and emit light of specific wavelengths, giving the ceramics photoluminescent properties [11].…”

Functional Ferroic Materials, Films and Devices

“…However, as lead is harmful to the environment and to humans, lead-free materials have been studied in the last decade to substitute lead-based materials. For example, Li et al prepared Bi 2 O 3 -doped (K 0.5 Na 0.5 )NbO 3 (KNN) lead-free ceramics and found that Bi 2 O 3 doping not only enhanced remanent polarization(Pr) from 8 µC/cm 2 for KNN to 18 µC/cm 2 for KNN-0.3%Bi 2 O 3 due to the creation of an orthogonal-tripartite phase at room temperature but also reduced the grain size and improved the grain size uniformity of ceramics [4]. Li et al found that piezoelectric constant d 33 = 678 pC/N and electromechanical coupling coefficient K p = 0.583 of (Ba 0.85 Ca 0.15 )(Zr 0.1 Ti 0.9 )O 3 ferroelectric ceramics could be achieved by the co-doping of CeO 2 and Y 2 O 3 [5].…”