Effects of Ca and Zr additions and stoichiometry on the electrical properties of barium titanate-based ceramics

Abstract

(Ba 1¹x Ca x ) m (Ti 1¹y Zr y )O 3 (BCTZ-x-y-m) ceramics were studied to clarify the effects of Ca and/or Zr addition and the nonstoichiometry of BCTZ ceramics. The range of each element was 0.00 ¼ x, y ¼ 0.25 and 0.995 ¼ m ¼ 1.02. All powders were prepared by a solid state reaction method. Green bodies with disc shapes were sintered at 1500°C for 2 h in air and then reheated at 950°C for 5 h in various reducing conditions. The dielectrics with the substitution of Ca ion in BCTZ-x-0.0-1.01 (x ¼ 0.10) showed an increase in T c and the insulation resistivity improved with increasing x. The increase of Zr content (y) in BCTZ-0.1-y-1.01 and m in BCTZ-0.1-0.1-m led to the phase transition of dielectrics to relaxors, accompanying the decrease of T c . In BCTZ-0.1-0.1-m, Ca and Zr co-doped dielectrics showed a high insulation resistivity (IR), even though m = 1.00. There are two possible origins of the higher resistivity observed in BCTZ with m = 1.0. The first is the acceptor action of Ca ions that moved from Ba sites to Ti sites in BaTiO 3 ; the second is the higher charge stability of the Zr ion than that of the Ti ion in a reducing atmosphere.

Lead-free Ba0.8Ca0.2(ZrxTi1−x)O3 ceramics with large electrocaloric effect

“…[22][23][24] The results agree well with the observed decrease of the tetragonal asymmetry caused by Zr substitution, thus minimizing the internal stresses that reduce successively the Curie temperature. In fact, the addition of Zr 4þ induces the weakening of bonding force between the B-site ion and oxygen ion of the BCTZ perovskite structure (given by ABO 3 ).…”

Electric field effect on the microstructure and properties of Ba0.9Ca0.1Ti0.9Zr0.1O3 (BCTZ) lead-free ceramics

“…Among them, noticeably, the (Ba1-xCax)(Ti1y Zr y) O 3 system has open a path for many research activities because of the large piezoelectric response produced by some compositions proximity to a triple point (TP), characterized by rhombohedral (R), tetragonal (T) and cubic phases coexistence 14 . This system has achieved great attention due to the possibility of tailoring the piezo-ferroelectrical properties by controlling the system stoichiometry 15 .…”

Chemical Synthesis, Sintering and Piezoelectric Properties of Ba0.85Ca0.15 Zr0.1Ti0.9O3 Lead‐Free Ceramics

“…The most common approach to fabricate these materials is by solid-state reaction (SSR) which usually results in acceptable phase purity and structural homogeneity. [6][7][8][9][10] On the other hand, however, the time required for homogenization of the raw materials, calcination and sintering is very long and the involve calcination and sintering temperatures up to 1250°C and 1500°C, respectively. Therefore, a range of advanced synthesis routes have been investigated with the aim to control the stoichiometry, reduce the particle size and reduce the processing time.…”

“…These features imply that the piezoelectric properties (e.g., d 33 ) of the (1− x )BZT‐ x BCT system are not only very dependent on the Ba/Ca or Zr/Ti ratio, but also on the temperature of measurement, with both factors able to influence the structure and thus the measured piezoelectric properties. The most common approach to fabricate these materials is by solid‐state reaction (SSR) which usually results in acceptable phase purity and structural homogeneity . On the other hand, however, the time required for homogenization of the raw materials, calcination and sintering is very long and the involve calcination and sintering temperatures up to 1250°C and 1500°C, respectively.…”