Microstructure and electrical properties of ultra high temperature (1-x)CaBi₂Nb₂O₉-xNa_{0 5}Bi_{2 5}Nb₂O₉ ceramics

Bismuth layer structured ferroelectric ceramics of (1-x)CaBi₂Nb₂O₉-xNa_{0 5}Bi_{2 5}Nb₂O₉ [(1-x) CBNO-xNBNO, 0≤x≤1 0] ceramics were obtained by conventional solid state reaction method. The effects of Na_{0 5}Bi_{2 5}Nb₂O₉ (NBNO) addition on the microstructure and electrical properties of ceramics have been studied. X-ray diffraction studies reveal that NBNO diffuses into the CBNO lattices to form a solid solution with an Aurivillius structure a pure orthorhombic space group A2₁am. The room temperature record Raman spectra of CBNO-NBNO ceramics with x50 0-0 8, the well defined phonon modes around 190, 587 and 820 cm^-1 are observed. They were all single phase ferroelectrics with high Curie points (∼900°C). Compared with CBNO, all the solid solution ceramics have a higher piezoelectric constant d₃₃, and a larger remnant polarisation (Pr). The 0 6CBNO-0 4NBNO ceramics possess the optimal piezoelectric properties, and the piezoelectric coefficient (d₃₃), Curie temperature (T_c), and remanent polarisation 2P_r were found to be 10 3 pC N^-1, 903°C and 5 0 μC cm^-2 respectively. These properties suggest that CBNONBNO system ceramics might be good candidates for high temperature piezoelectric applications.