Electric Properties of [(BaO)1.00(XO)x](Ti0.95Zr0.05)O2 (X = Ca, Sr, Ba) Ceramics Fired under Reduced Atmosphere

Abstract

Ba(Ti0.95Zr0.05)O3 doped with CaO, SrO, or BaO was investigated in order to develop materials suitable for lead-free actuators with resistance to reduction. The grain sizes of [(BaO)1.00(XO)x](Ti0.95Zr0.05)O2 (X = Ca, Sr, Ba; x = 0–0.05) ceramics decreased with increasing amount of dopant concentration x. The grain sizes of the ceramics with a dopant concentration x in the range of 0.005 to 0.05 are approximately 1–2 µm. The crystalline phases of the ceramics with a dopant concentration x = 0.01 or less were perovskite single phases. CaO, SrO, or BaO doping concentrations of x = 0.005 or more were effective for preventing the reduction of Ba(Ti0.95Zr0.05)O3 during firing under 3% H2–N2 atmosphere. The remanent polarizations and dynamic piezoelectric constants of the ceramics decreased with increasing dopant concentration of CaO, SrO, or BaO. The dynamic piezoelectric constant of the ceramics with BaO dopant concentration x of 0.005 was approximately 640 pm/V. The Curie temperature was approximately 109 °C in this composition.