Dielectric and piezoelectric properties and PTC behavior of Ba0.9Ca0.1Ti0.9Zr0.1O3−xLa ceramics prepared by hydrothermal method

Lead-free Ba_0.9Ca_0.1Ti_0.9Zr_0.1O₃–xLa (x=0.000, 0.005, 0.010, 0.015, and 0.020) ceramics have been prepared by hydrothermal method and were assisted by fast microwave sintering, and the effects of La-doping on the electrical properties of Ba_0.9Ca_0.1Ti_0.9Zr_0.1O₃ were studied. The single orthorhombic phase was observed in the composition of x≤0.10 and the coexistence of orthorhombic and tetragonal phase were detected at x=0.015 and 0.020. The substitution of small amount of La³⁺ resulted in an decreasing of dielectric constant and dielectric loss, and they both possessed a minimum value at x=0.010. With the addition of x≥0.015, the Ba_0.9Ca_0.1Ti_0.9Zr_0.1O₃–xLa ceramics became semi-conductors and the PTC behavior was observed. The piezoelectric constant (d₃₃) measured at 50 °C of the ceramics were increased after the partial substitution of La³⁺ because of the enhancement of coexistence of orthorhombic and tetragonal phases. The T_C was decreased with increasing La³⁺, and the ferroelectric and piezoelectric properties cannot be detected at samples with x=0.02.

This paper was originally published in Materials Letters, 118 (2014), Pages 1-4.