High temperature properties of manganese modified CaBi4O15 ferroelectric ceramics

The dielectric, piezoelectric and electromechanical properties of manganese modified CaBi4Ti4O15 (CBT) bismuth layer-structured ferroelectric ceramics were determined in the range of room temperature to similar to 800 degrees C. The room temperature dielectric permittivity and dielectric loss were found to be 148 and 0.2%, respectively. The piezoelectric coefficients, d(33) and d(15), were 14 pC/N and 9 pC/N, with electromechanical coupling factors k'(33) 8.4% and k(15) = 5.5%. The mechanical quality factor Q (sliver extensional mode) was 4300 at room temperature, decreasing with increasing temperature. The remnant polarization and coercive field were found to be 5.2 mu C/cm(2) and 88 kV/cm, respectively. The excellent piezoelectric, mechanical properties, together with its high Curie temperature (similar to 800 degrees C) and high electrical resistivity (1 x 10(7) Omega cm at 500 degrees C), demonstrated the potential of manganese modified CBT ceramics for ultra-high temperature sensing applications. (c) 2006 Elsevier Ltd. All rights reserved.