Ferroelectric, piezoelectric properties and thermal expansion of new Bi(Ni3/4W1/4)O3-PbTiO3 solid solutions

Ceramics of the Bi(Ni3/4W1/4)O-3-PbTiO3 (BNW-PT) ferroelectric system were synthesized using a conventional solid-state sintering process. A morphotropic phase boundary (MPB) region separating tetragonal and rhombohedral phases has been determined based on X-ray diffraction (XRD) analysis. The composition-dependent phase transition behavior, thermal expansion, di/ferro/piezoelectric properties have been systemically investigated. The volume TECs (thermal expansion coefficients) for 0.1BNW-0.9PT and 0.2BNW-0.8PT are -1.01 x 10(-5) per degrees C and -0.94 x 10(-5) per degrees C, respectively, indicating the negative thermal expansion of some compositions for the binary system. The BNW-PT ceramics have Curie temperatures, T-C, ranging from 460 degrees C to similar to 152 degrees C with the variation of BNW constituent. The tetragonal-rich composition 0.20BNW-0.80PT is found to have the largest remnant polarization, P-r similar to 23.4 mu C cm(-2). The highest piezoelectric coefficient d(33) similar to 145 pC N-1 is achieved at MPB composition 0.32BNW-0.68PT. The maximum strain value similar to 0.194% is also obtained in the 0.32BNW-0.68PT ceramic.