Dielectric and Piezoelectric Properties in the System: (1−x)[(Na_0.5K_0.5NbO₃)_0.93–(LiTaO₃)_0.07]–x[BiScO₃]

Abstract

Solid solution formation in the system (1−x) [(Na0.5K0.5NbO3)0.93–(LiTaO3)0.07]−x[BiScO3] has been investigated for compositions, 0≤x≤0.05. The tetragonal c/a ratio decreases with increasing BiScO3 content, with a discontinuity at x=0.02, X‐ray diffraction patterns appear pseudo‐cubic for x>0.02. There is a 10‐fold reduction in grain size between x=0.015 and x=0.02: dielectric peaks become suppressed and broadened at this point. Piezoelectric d33 charge coefficients decrease across the compositional range. Results are discussed in terms of chemical inhomogeneity and grain‐size effects.

Low variation in relative permittivity over the temperature range 25–450°C for ceramics in the system (1−x)[Ba0.8Ca0.2TiO3]–x[Bi(Zn0.5Ti0.5)O3]

“…Another approach to exploring high temperature dielectrics is to investigate the properties of normal ferroelectrics with high temperature Curie points, T c and with invariant relative permittivity to below roomtemperature [6,8,14].…”

“…A range of lead-free ceramics have been investigated in the search for new hightemperature dielectrics, including compositions in the solid solution series: BaTiO 3 -Ba(Zn 0.5 Ti 0.5 )O 3 [4]; BaTiO 3 -Ba(Zn 0.5 Ti 0.5 )O 3 -BiScO 3 [5]; Na 0.5 K 0.5 NbO 3 -LiTaO 3 -BiScO 3 [6,8]; Na 0. 5 Bi 0.5 TiO 3 -KTaO 3 [7]; BiScO 3 -BaTiO 3 -K 0.…”

“…However the relatively high Sc 2 O 3 content in this optimum composition has cost implications that may be an obstacle to commercial implementation [9]. A number of other potential high temperature dielectrics also contain a significant proportions of scandium oxide [1,5,6,8,13,14] 800 ºC-1100 ºC for 3 h. The calcined powders were ball milled for 24 h and shaped into pellets by uniaxial pressing in a 10 mm steel die at 65 MPa, followed by cold isostatic pressing at 300 MPa. A binder (Ciba Glascol HA4) was introduced during the post-calcination milling stage.…”

Lead-free (K, Na)NbO3 ferroelectric thin films: Preparation, structure and electrical properties

“…Among several lead-free piezoelectric materials, K 0.5 Na 0.5 NbO 3 (KNN) is a promising candidate, as it has a high Curie temperature, good ferroelectric and piezoelectric properties as well as biocompatibility [2]. Therefore, a number of modified KNN ceramics have been extensively studied to improve their electrical properties [3][4][5][6][7][8][9][10][11]. Compared with bulk materials, ferroelectric and piezoelectric thin films are important for memory and micro-sensor as well as micro-actuator applications [12].…”

Dielectric ceramic with stable relative permittivity and low loss from −60 to 300°C: A potential high temperature capacitor material

“…The materials are compositionally modified perovskites, ABO3 which incorporate Bi 3+ on A-sites [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] as reviewed in reference [21], for example (1-x)BaTiO3 -xBi(Mg0.5Ti0.5)O3 solid solutions [3][4][5][6][7]. The level of stability in r(T) for (1-x)BaTiO3 -xBi(Mg0.5Ti0.5)O3 becomes more pronounced with additional Ca 2+ substitution, giving r values ~ 1000 ± 15 % (1 kHz) from 80 -500 °C [3].…”