Dielectric and Impedance Analysis on the Electrical Response of Lead-Free Ba1−xCaxTi0.9Zr0.1O3 Ceramics at High Temperature Range

• Published in: Applied sciences Vol. 7; no. 3; p. 214
• Main Authors: Reyes-Montero, Armando, Ramos-Alvarez, Paola, González, Amador, López-Juárez, Rigoberto, Villafuerte-Castrejón, María
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 2017
• Subjects: BCTZ ceramics; Boundary processes; Calcium; Calcium ions; Ceramics; Composition; Conduction; Dielectric properties; dielectric response; Diffraction; Electrical properties; Ferroelectric materials; Grain size; High temperature; Impedance; impedance spectroscopy; Lead free; Perovskite structure; Perovskites; Solid solutions; Temperature effects; Transition temperatures; X-ray diffraction
• ISSN: 2076-3417; 2076-3417
• DOI: 10.3390/app7030214

Ba1−xCaxTi0.9Zr0.1O3 (x = 0.10, 0.15, 0.18) solid solutions were synthesized by the conventional solid-state method. A perovskite-type structure was determined using the X-ray diffraction (XRD) technique. The addition of Ca2+ reduced the grain size (22.6, 17.9 and 13.3 μm, respectively) for all well-sintered ceramics (≈98%). Moreover, the stability temperature ranges for the tetragonal phase were promoted by displacing the ferroelectric-ferroelectric phase’s transition temperatures while TC was maintained (86 °C). The electrical performance of the material improved as the stoichiometric composition was positioned near the morphotropic phase boundary (x = 0.15): εr ≈ 16,500 (TC) at 1 kHz. For T > TC, a thermally activated relaxation process occurred. In addition, the bulk and grain boundary processes were responsible for the conduction mechanisms. The composition x = 0.15 showed an activation energy of Ea = 1.49 eV with a maximum conductivity of σmax = 2.48 × 10−2 S•cm−1 at 580 °C. Systematic studies at high temperature for dielectric properties were accomplished for analyzing electrical inhomogeneities associated with the grain, grain boundaries or surfaces, which are important for device design and a fundamental electrical characterization.