Dielectric and piezoelectric properties of lead-free K_0.5Na_0.5NbO₃–LiSbO₃–Bi_0.5Li_0.5TiO₃ system

Abstract

The effects of Bi, Li and Ti substitutions for K, Na, Li, Nb and Sb on the piezoelectric properties of (1 x)(K 0.474 Na 0.474 Li 0.052 )-(Nb 0.948 Sb 0.052 )O 3 xBi 0.5 Li 0.5 TiO 3 [(1 x)KNLNSxBLT] ceramics were investigated. X-ray powder diffraction profiles indicate the formation of a morphotropic phase boundary (MPB) between the orthorhombic and tetragonal phases in the (1 x)KNLNS xBLT ceramics. The ratio of tetragonal to orthorhombic phase increased with x, which suggests a decrease in the orthorhombictetragonal phase transition temperature (T OT ). The dielectric constant at room temperature was increased by the substitution of Bi, Li and Ti for K, Na, Li, Nb and Sb. In addition, the temperature dependence of the dielectric constant indicated a T OT shift from approximately 90°C to room temperature, and resulted in a piezoelectric constant of 272 pC/N for the 0.98KNLNS-0.02BLT (x = 0.02) ceramic.

Comprehensive analysis of the temperature dependence of the crystal structure of (1−x)K0.5Na0.5NbO3–xBa(Li1/4Nb3/4)O3piezoelectric ceramics

“…Upon increasing the composition x , the peak intensity of (002) reflection of the tetragonal phase increased. Such variations in the peak intensities have also been reported based on work with other KNN-based solid solutions, such as KNN–LN, 32,33 KNN–LS, 34 KNN–LT 35 and KNN–LS–Bi 0.5 Li 0.5 TiO 3 , 36 which consisted of orthorhombic and tetragonal phases. Therefore, it is considered that the BaLN addition enhances the formation of the tetragonal phase; (1− x )KNN– x BaLN ceramics above x = 0.005 consist of a mixture of orthorhombic and tetragonal phases.…”

Selection and Optimization of a K0.5Na0.5NbO3-Based Material for Environmentally-Friendly Magnetoelectric Composites

“…Figure 1 shows the XRD patterns for the nine studied LKNNT compositions. All powdered samples were basically perovskite single-phase, but for a small amount of K 3 Li 2 Nb 5 O 15 secondary phase with tetragonal tungsten bronze structure, which is commonly found in Li-doped KNN-based materials [45,46]. This secondary phase, present as a very small fraction of the major perovskite phase, is eliminated during the subsequent sintering process.…”